Slips

Code

Create a Application which shows Life Cycle of Activity.
package com.example.lifecycledemo;
import android.os.Bundle;
import android.util.Log;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

private static final String TAG = "LifecycleDemo";

// onCreate() is called when the activity is first created
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.d(TAG, "onCreate() called");
}

// onStart() is called when the activity becomes visible to the user
@Override
protected void onStart() {
super.onStart();
Log.d(TAG, "onStart() called");
}

// onResume() is called when the activity starts interacting with the user
@Override
protected void onResume() {
super.onResume();
Log.d(TAG, "onResume() called");
}

// onPause() is called when the system is about to start resuming another activity
@Override
protected void onPause() {
super.onPause();
Log.d(TAG, "onPause() called");
}

// onStop() is called when the activity is no longer visible to the user
@Override
protected void onStop() {
super.onStop();
Log.d(TAG, "onStop() called");
}

// onRestart() is called when the activity is coming back to interact with the user
@Override
protected void onRestart() {
super.onRestart();
Log.d(TAG, "onRestart() called");
}

// onDestroy() is called before the activity is destroyed
@Override
protected void onDestroy() {
super.onDestroy();
Log.d(TAG, "onDestroy() called");
}
}
Create an Android Application to accept two numbers to calculate it’s Power and Average. Create two buttons: Power and Average. Display the appropriate result on the next activity on Button click.
activity_main.xml:
-----------------------
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="16dp">
<EditText
android:id="@+id/number1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Enter First Number"
android:inputType="numberDecimal" />
<EditText
android:id="@+id/number2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Enter Second Number"
android:inputType="numberDecimal" />
<Button
android:id="@+id/powerButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Calculate Power"
android:layout_marginTop="20dp" />
<Button
android:id="@+id/averageButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Calculate Average"
android:layout_marginTop="20dp" />
</LinearLayout>
MainActivity.java
----------------------
package com.example.calculator;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {
EditText number1EditText, number2EditText;
Button powerButton, averageButton;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
number1EditText = findViewById(R.id.number1);
number2EditText = findViewById(R.id.number2);
powerButton = findViewById(R.id.powerButton);
averageButton = findViewById(R.id.averageButton);
powerButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
calculatePower();
}
});
averageButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
calculateAverage();
}
});
}
private void calculatePower() {
try {
double num1 = Double.parseDouble(number1EditText.getText().toString());
double num2 = Double.parseDouble(number2EditText.getText().toString());
double power = Math.pow(num1, num2);
// Pass result to ResultActivity
Intent intent = new Intent(MainActivity.this, ResultActivity.class);
intent.putExtra("resultType", "Power");
intent.putExtra("result", power);
startActivity(intent);
} catch (NumberFormatException e) {
Toast.makeText(MainActivity.this, "Please enter valid numbers", Toast.LENGTH_SHORT).show();
}
private void calculateAverage() {
try {
double num1 = Double.parseDouble(number1EditText.getText().toString());
double num2 = Double.parseDouble(number2EditText.getText().toString());
double average = (num1 + num2) / 2;
// Pass result to ResultActivity
Intent intent = new Intent(MainActivity.this, ResultActivity.class);
intent.putExtra("resultType", "Average");
intent.putExtra("result", average);
startActivity(intent);
} catch (NumberFormatException e) {
Toast.makeText(MainActivity.this, "Please enter valid numbers", Toast.LENGTH_SHORT).show();
}
activity_result.xml
-----------------------
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:gravity="center"
android:padding="16dp">
<TextView
android:id="@+id/resultTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Result"
android:textSize="24sp"
android:layout_marginBottom="20dp"/>
<TextView
android:id="@+id/resultText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Result will be displayed here"
android:textSize="20sp" />
</LinearLayout>
ResultActivity.java
-----------------------
package com.example.calculator;
import android.os.Bundle;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
public class ResultActivity extends AppCompatActivity {
TextView resultTitle, resultText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_result);
resultTitle = findViewById(R.id.resultTitle);
resultText = findViewById(R.id.resultText);
// Get the result and type from the Intent
String resultType = getIntent().getStringExtra("resultType");
double result = getIntent().getDoubleExtra("result", 0);
resultTitle.setText(resultType);
resultText.setText(String.valueOf(result));
}
Create application using JSON to provide Employee Information.
Create a folder named assets inside the src/main directory, and add the employee.json file there.
`assets/employee.json`

[
    {
        "name": "John Doe",
        "position": "Software Engineer",
        "salary": "70000"
    },
    {
        "name": "Jane Smith",
        "position": "Product Manager",
        "salary": "80000"
    },
    {
        "name": "Emily Johnson",
        "position": "Designer",
        "salary": "60000"
    }
]

activity_main.xml
-----------------
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="16dp"/>

</LinearLayout>

item_employee.xml
-----------------
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:padding="16dp"
    android:background="?android:attr/selectableItemBackground"
    android:layout_marginBottom="8dp">

    <TextView
        android:id="@+id/name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="18sp"
        android:textStyle="bold" />

    <TextView
        android:id="@+id/position"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="16sp"
        android:textColor="#757575" />

    <TextView
        android:id="@+id/salary"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="14sp"
        android:textColor="#4CAF50"
        android:layout_marginTop="8dp"/>
</LinearLayout>


Now we need to create the necessary Java classes to parse the JSON data and display it in the RecyclerView.

Employee.java
--------------
package com.example.employeeinfo;

public class Employee {
    private String name;
    private String position;
    private String salary;

    // Constructor
    public Employee(String name, String position, String salary) {
        this.name = name;
        this.position = position;
        this.salary = salary;
    }

    // Getters
    public String getName() {
        return name;
    }

    public String getPosition() {
        return position;
    }

    public String getSalary() {
        return salary;
    }
}

EmployeeAdapter.java
--------------------

package com.example.employeeinfo;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import androidx.recyclerview.widget.RecyclerView;
import java.util.List;

public class EmployeeAdapter extends RecyclerView.Adapter<EmployeeAdapter.EmployeeViewHolder> {
    private List<Employee> employeeList;

    // Constructor
    public EmployeeAdapter(List<Employee> employeeList) {
        this.employeeList = employeeList;
    }

    @Override
    public EmployeeViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.item_employee, parent, false);
        return new EmployeeViewHolder(view);
    }

    @Override
    public void onBindViewHolder(EmployeeViewHolder holder, int position) {
        Employee employee = employeeList.get(position);
        holder.nameTextView.setText(employee.getName());
        holder.positionTextView.setText(employee.getPosition());
        holder.salaryTextView.setText("Salary: $" + employee.getSalary());
    }

    @Override
    public int getItemCount() {
        return employeeList.size();
    }

    public static class EmployeeViewHolder extends RecyclerView.ViewHolder {
        TextView nameTextView, positionTextView, salaryTextView;

        public EmployeeViewHolder(View itemView) {
            super(itemView);
            nameTextView = itemView.findViewById(R.id.name);
            positionTextView = itemView.findViewById(R.id.position);
            salaryTextView = itemView.findViewById(R.id.salary);
        }
    }
}

MainActivity.java
-----------------

package com.example.employeeinfo;

import android.content.res.AssetManager;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.lang.reflect.Type;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private RecyclerView recyclerView;
    private EmployeeAdapter adapter;
    private List<Employee> employeeList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        recyclerView = findViewById(R.id.recyclerView);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));

        // Load employee data from JSON file
        loadEmployeeData();
    }

    private void loadEmployeeData() {
        try {
            // Load the JSON data from the assets folder
            AssetManager assetManager = getAssets();
            BufferedReader reader = new BufferedReader(new InputStreamReader(assetManager.open("employee.json")));
            StringBuilder stringBuilder = new StringBuilder();
            String line;
            while ((line = reader.readLine()) != null) {
                stringBuilder.append(line);
            }
            String jsonData = stringBuilder.toString();

            // Parse the JSON data using Gson
            Gson gson = new Gson();
            Type employeeListType = new TypeToken<List<Employee>>() {}.getType();
            employeeList = gson.fromJson(jsonData, employeeListType);

            // Set up RecyclerView with parsed data
            adapter = new EmployeeAdapter(employeeList);
            recyclerView.setAdapter(adapter);

        } catch (Exception e) {
            e.printStackTrace();
            Toast.makeText(this, "Error loading employee data", Toast.LENGTH_SHORT).show();
        }
    }
}

Construct an Android application to accept a number and calculate Armstrong and Perfect
number of a given number.
activity_main.xml
----------------------
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp"
    android:gravity="center">

    <EditText
        android:id="@+id/numberInput"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter a number"
        android:inputType="number"
        android:layout_marginBottom="20dp" />

    <Button
        android:id="@+id/armstrongButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Check Armstrong Number"
        android:layout_marginBottom="10dp"/>

    <Button
        android:id="@+id/perfectButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Check Perfect Number"
        android:layout_marginBottom="20dp"/>

    <TextView
        android:id="@+id/resultText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text=""
        android:textSize="18sp"
        android:textColor="#FF0000"/>
</LinearLayout>

MainActivity.java
----------------------
package com.example.numbercheck;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    EditText numberInput;
    Button armstrongButton, perfectButton;
    TextView resultText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize views
        numberInput = findViewById(R.id.numberInput);
        armstrongButton = findViewById(R.id.armstrongButton);
        perfectButton = findViewById(R.id.perfectButton);
        resultText = findViewById(R.id.resultText);

        // Set listeners for buttons
        armstrongButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                checkArmstrongNumber();
            }
        });

        perfectButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                checkPerfectNumber();
            }
        });
    }

    // Method to check if the number is Armstrong
    private void checkArmstrongNumber() {
        String input = numberInput.getText().toString();

        if (input.isEmpty()) {
            Toast.makeText(MainActivity.this, "Please enter a number", Toast.LENGTH_SHORT).show();
            return;
        }

        int number = Integer.parseInt(input);
        int originalNumber = number;
        int sum = 0;
        int digits = String.valueOf(number).length();

        while (number > 0) {
            int remainder = number % 10;
            sum += Math.pow(remainder, digits);  // Raise each digit to the power of number of digits
            number /= 10;
        }

        if (sum == originalNumber) {
            resultText.setText(originalNumber + " is an Armstrong Number.");
        } else {
            resultText.setText(originalNumber + " is not an Armstrong Number.");
        }
    }

    // Method to check if the number is Perfect
    private void checkPerfectNumber() {
        String input = numberInput.getText().toString();

        if (input.isEmpty()) {
            Toast.makeText(MainActivity.this, "Please enter a number", Toast.LENGTH_SHORT).show();
            return;
        }

        int number = Integer.parseInt(input);
        int sum = 0;

        // Find the divisors of the number
        for (int i = 1; i <= number / 2; i++) {
            if (number % i == 0) {
                sum += i;
            }
        }

        if (sum == number) {
            resultText.setText(number + " is a Perfect Number.");
        } else {
            resultText.setText(number + " is not a Perfect Number.");
        }
    }
}

Write a Java Android Program to Demonstrate List View Activity with all operations
Such as: Insert, Delete, Search

activity_main.xml
----------------------
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <!-- EditText to input item to be added -->
    <EditText
        android:id="@+id/editTextItem"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter item to add"
        android:inputType="text" />

    <!-- Button to Insert item -->
    <Button
        android:id="@+id/btnInsert"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Insert Item"
        android:layout_marginTop="10dp" />

    <!-- EditText to search the ListView items -->
    <EditText
        android:id="@+id/editTextSearch"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Search items"
        android:layout_marginTop="20dp" />

    <!-- ListView to show items -->
    <ListView
        android:id="@+id/listViewItems"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:layout_marginTop="20dp"/>

</LinearLayout>

MainActivity.java
----------------------
package com.example.listviewoperations;

import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;
import android.widget.TextView;
import android.widget.Filter;
import android.widget.Filterable;

import androidx.appcompat.app.AppCompatActivity;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    // Declare UI elements
    EditText editTextItem, editTextSearch;
    Button btnInsert;
    ListView listViewItems;

    // Declare ArrayList to store the list items
    ArrayList<String> itemList;
    ArrayAdapter<String> adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize the UI elements
        editTextItem = findViewById(R.id.editTextItem);
        editTextSearch = findViewById(R.id.editTextSearch);
        btnInsert = findViewById(R.id.btnInsert);
        listViewItems = findViewById(R.id.listViewItems);

        // Initialize the ArrayList and Adapter
        itemList = new ArrayList<>();
        adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, itemList);

        // Set the adapter for the ListView
        listViewItems.setAdapter(adapter);

        // Insert item when Insert button is clicked
        btnInsert.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String item = editTextItem.getText().toString();
                if (!item.isEmpty()) {
                    itemList.add(item); // Add item to list
                    adapter.notifyDataSetChanged(); // Refresh the ListView
                    editTextItem.setText(""); // Clear the input field
                    Toast.makeText(MainActivity.this, "Item Added", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(MainActivity.this, "Please enter an item", Toast.LENGTH_SHORT).show();
                }
            }
        });

        // Set an item click listener to delete an item when clicked
        listViewItems.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                String item = itemList.get(position);
                itemList.remove(position); // Remove item from list
                adapter.notifyDataSetChanged(); // Refresh the ListView
                Toast.makeText(MainActivity.this, item + " Deleted", Toast.LENGTH_SHORT).show();
            }
        });

        // Implement search functionality
        editTextSearch.addTextChangedListener(new android.text.TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence charSequence, int start, int count, int after) {}

            @Override
            public void onTextChanged(CharSequence charSequence, int start, int before, int count) {
                // Filter the list as the user types in the search box
                adapter.getFilter().filter(charSequence);
            }

            @Override
            public void afterTextChanged(android.text.Editable editable) {}
        });
    }
}

Create an application to demonstrate login form with validation.
LoginActivity.java
------------------
package com.example.loginvalidation;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

public class LoginActivity extends AppCompatActivity {

    EditText editTextUsername, editTextPassword;
    Button buttonLogin;
    TextView textViewError;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        // Initialize the views
        editTextUsername = findViewById(R.id.editTextUsername);
        editTextPassword = findViewById(R.id.editTextPassword);
        buttonLogin = findViewById(R.id.buttonLogin);
        textViewError = findViewById(R.id.textViewError);

        // Set the login button's onClickListener
        buttonLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // Validate login
                validateLogin();
            }
        });
    }

    private void validateLogin() {
        String username = editTextUsername.getText().toString().trim();
        String password = editTextPassword.getText().toString().trim();

        // Simple validation: Check if fields are empty
        if (username.isEmpty() || password.isEmpty()) {
            textViewError.setText("Please enter both username and password.");
        } 
        // Hardcoded correct credentials (just for simplicity)
        else if (username.equals("user") && password.equals("12345")) {
            // If login is successful, show a Toast message (or you can navigate to a new activity)
            Toast.makeText(LoginActivity.this, "Login Successful! Welcome " + username, Toast.LENGTH_SHORT).show();
        } else {
            // Invalid credentials
            textViewError.setText("Invalid username or password.");
        }
    }
}

activity_login.xml
------------------
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="32dp"
    android:gravity="center">

    <!-- EditText for Username -->
    <EditText
        android:id="@+id/editTextUsername"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Username"
        android:inputType="text"/>

    <!-- EditText for Password -->
    <EditText
        android:id="@+id/editTextPassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Password"
        android:inputType="textPassword"
        android:layout_marginTop="16dp"/>

    <!-- Button for Login -->
    <Button
        android:id="@+id/buttonLogin"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Login"
        android:layout_marginTop="32dp"/>

    <!-- TextView to display error messages -->
    <TextView
        android:id="@+id/textViewError"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#FF0000"
        android:layout_marginTop="16dp"/>

</LinearLayout>

AndroidManifest.xml
-------------------
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.loginvalidation">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="Login Validation"
        android:theme="@style/Theme.AppCompat.Light">

        <activity android:name=".LoginActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>

</manifest>


Write a Java Android Program to Demonstrate List View Activity with all operations
Such as: Insert, Delete, Search
activity_main.xml
----------------------

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <!-- EditText for user input -->
    <EditText
        android:id="@+id/editTextMessage"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter greet message" />

    <!-- Button to send message to the second activity -->
    <Button
        android:id="@+id/buttonSendMessage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Send Message" />

</LinearLayout>


MainActivity.java
-----------------
package com.example.greetmessageapp;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private EditText editTextMessage;
    private Button buttonSendMessage;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        editTextMessage = findViewById(R.id.editTextMessage);
        buttonSendMessage = findViewById(R.id.buttonSendMessage);

        // Set OnClickListener to the button
        buttonSendMessage.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // Get the message entered by the user
                String greetMessage = editTextMessage.getText().toString();

                // Create an intent to start the second activity
                Intent intent = new Intent(MainActivity.this, SecondActivity.class);

                // Pass the greet message to the second activity
                intent.putExtra("GREET_MESSAGE", greetMessage);

                // Start the second activity
                startActivity(intent);
            }
        });
    }
}

activity_second.xml
-------------------
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <!-- TextView to display the greet message -->
    <TextView
        android:id="@+id/textViewGreetMessage"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Greet message will be displayed here"
        android:textSize="18sp" />

</LinearLayout>

SecondActivity.java
--------------------
package com.example.greetmessageapp;

import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;

public class SecondActivity extends AppCompatActivity {

    private TextView textViewGreetMessage;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);

        textViewGreetMessage = findViewById(R.id.textViewGreetMessage);

        // Get the greet message from the Intent
        Intent intent = getIntent();
        String greetMessage = intent.getStringExtra("GREET_MESSAGE");

        // Display the greet message
        textViewGreetMessage.setText(greetMessage);
    }
}

AndroidManifest.xml
-------------------
<application
    ... >
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <activity android:name=".SecondActivity" />
</application>


Create an application to change Font Size, Color and Font Family of String.
activity_main.xml
------------------
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="20dp">

    <!-- TextView to display the string -->
    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Change My Style"
        android:textSize="18sp"
        android:layout_gravity="center"
        android:padding="20dp"
        android:textColor="#000000"/>

    <!-- Button to change font size -->
    <Button
        android:id="@+id/btnChangeSize"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Change Font Size"
        android:layout_gravity="center"
        android:layout_marginTop="20dp"/>

    <!-- Button to change text color -->
    <Button
        android:id="@+id/btnChangeColor"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Change Text Color"
        android:layout_gravity="center"
        android:layout_marginTop="20dp"/>

    <!-- Button to change font family -->
    <Button
        android:id="@+id/btnChangeFamily"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Change Font Family"
        android:layout_gravity="center"
        android:layout_marginTop="20dp"/>

</LinearLayout>

MainActivity.java
------------------
package com.example.fontchanger;

import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private TextView textView;
    private Button btnChangeSize, btnChangeColor, btnChangeFamily;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize the views
        textView = findViewById(R.id.textView);
        btnChangeSize = findViewById(R.id.btnChangeSize);
        btnChangeColor = findViewById(R.id.btnChangeColor);
        btnChangeFamily = findViewById(R.id.btnChangeFamily);

        // Change Font Size on Button Click
        btnChangeSize.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                textView.setTextSize(30);  // Change text size to 30sp
            }
        });

        // Change Text Color on Button Click
        btnChangeColor.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                textView.setTextColor(Color.RED);  // Change text color to red
            }
        });

        // Change Font Family on Button Click
        btnChangeFamily.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                textView.setTypeface(getResources().getFont(R.font.roboto_regular));  // Change to Roboto font family
            }
        });
    }
}

AndroidManifest.xml
-------------------
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.fontchanger">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="Font Changer"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.FontChanger">

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>

</manifest>

Create an application for registration form given below. Also perform appropriate validation.
activity_main.xml
-----------------
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp"
    android:gravity="center">

    <!-- Name Field -->
    <EditText
        android:id="@+id/edtName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter Name"
        android:inputType="textPersonName"/>

    <!-- Email Field -->
    <EditText
        android:id="@+id/edtEmail"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter Email"
        android:inputType="textEmailAddress"
        android:layout_marginTop="10dp"/>

    <!-- Password Field -->
    <EditText
        android:id="@+id/edtPassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter Password"
        android:inputType="textPassword"
        android:layout_marginTop="10dp"/>

    <!-- Age Field -->
    <EditText
        android:id="@+id/edtAge"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter Age"
        android:inputType="number"
        android:layout_marginTop="10dp"/>

    <!-- Mobile Number Field -->
    <EditText
        android:id="@+id/edtMobile"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter Mobile Number"
        android:inputType="phone"
        android:layout_marginTop="10dp"/>

    <!-- Register Button -->
    <Button
        android:id="@+id/btnRegister"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Register"
        android:layout_marginTop="20dp"/>
    
</LinearLayout>

MainActivity.java
-----------------
package com.example.registrationform;

import android.os.Bundle;
import android.text.TextUtils;
import android.util.Patterns;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private EditText edtName, edtEmail, edtPassword, edtAge, edtMobile;
    private Button btnRegister;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize views
        edtName = findViewById(R.id.edtName);
        edtEmail = findViewById(R.id.edtEmail);
        edtPassword = findViewById(R.id.edtPassword);
        edtAge = findViewById(R.id.edtAge);
        edtMobile = findViewById(R.id.edtMobile);
        btnRegister = findViewById(R.id.btnRegister);

        // Register button click listener
        btnRegister.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // Validate form fields
                if (validateForm()) {
                    // If valid, show a success message
                    Toast.makeText(MainActivity.this, "Registration Successful", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }

    private boolean validateForm() {
        // Get user input values
        String name = edtName.getText().toString().trim();
        String email = edtEmail.getText().toString().trim();
        String password = edtPassword.getText().toString().trim();
        String ageString = edtAge.getText().toString().trim();
        String mobile = edtMobile.getText().toString().trim();

        // Validate Name
        if (TextUtils.isEmpty(name)) {
            edtName.setError("Name is required");
            edtName.requestFocus();
            return false;
        }

        // Validate Email
        if (TextUtils.isEmpty(email) || !Patterns.EMAIL_ADDRESS.matcher(email).matches()) {
            edtEmail.setError("Enter a valid email address");
            edtEmail.requestFocus();
            return false;
        }

        // Validate Password
        if (TextUtils.isEmpty(password) || password.length() < 6) {
            edtPassword.setError("Password must be at least 6 characters");
            edtPassword.requestFocus();
            return false;
        }

        // Validate Age (Should be a valid number)
        if (TextUtils.isEmpty(ageString)) {
            edtAge.setError("Age is required");
            edtAge.requestFocus();
            return false;
        } else {
            try {
                int age = Integer.parseInt(ageString);
                if (age < 18) {
                    edtAge.setError("You must be at least 18 years old");
                    edtAge.requestFocus();
                    return false;
                }
            } catch (NumberFormatException e) {
                edtAge.setError("Invalid age format");
                edtAge.requestFocus();
                return false;
            }
        }

        // Validate Mobile Number
        if (TextUtils.isEmpty(mobile) || mobile.length() != 10) {
            edtMobile.setError("Enter a valid 10-digit mobile number");
            edtMobile.requestFocus();
            return false;
        }

        return true;  // If all validations pass
    }
}

AndroidManifest.xml
-------------------
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.registrationform">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="Registration Form"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.RegistrationForm">

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>
</manifest>


Create an application that Demonstrates List View and Onclick of List Display with Toast
Message.

activity_main.xml
-----------------
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <!-- Registration Form Section -->
    <EditText
        android:id="@+id/edtName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter Name"
        android:inputType="textPersonName" />

    <EditText
        android:id="@+id/edtEmail"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter Email"
        android:inputType="textEmailAddress"
        android:layout_marginTop="10dp" />

    <EditText
        android:id="@+id/edtPassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter Password"
        android:inputType="textPassword"
        android:layout_marginTop="10dp" />

    <EditText
        android:id="@+id/edtAge"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter Age"
        android:inputType="number"
        android:layout_marginTop="10dp" />

    <EditText
        android:id="@+id/edtMobile"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter Mobile Number"
        android:inputType="phone"
        android:layout_marginTop="10dp" />

    <Button
        android:id="@+id/btnRegister"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Register"
        android:layout_marginTop="20dp" />

    <!-- ListView Section -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Click on List Item Below"
        android:textSize="18sp"
        android:layout_marginTop="30dp" />

    <ListView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp" />

</LinearLayout>

MainActivity.java
-----------------
package com.example.registrationlistview;

import android.os.Bundle;
import android.text.TextUtils;
import android.util.Patterns;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private EditText edtName, edtEmail, edtPassword, edtAge, edtMobile;
    private Button btnRegister;
    private ListView listView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize views
        edtName = findViewById(R.id.edtName);
        edtEmail = findViewById(R.id.edtEmail);
        edtPassword = findViewById(R.id.edtPassword);
        edtAge = findViewById(R.id.edtAge);
        edtMobile = findViewById(R.id.edtMobile);
        btnRegister = findViewById(R.id.btnRegister);
        listView = findViewById(R.id.listView);

        // Set up ListView with some items
        String[] items = {"Item 1", "Item 2", "Item 3", "Item 4", "Item 5"};
        ArrayAdapter<String> adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, items);
        listView.setAdapter(adapter);

        // Set up ListView item click listener
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                // Show a Toast with the item clicked
                String item = (String) parent.getItemAtPosition(position);
                Toast.makeText(MainActivity.this, "You clicked: " + item, Toast.LENGTH_SHORT).show();
            }
        });

        // Register button click listener
        btnRegister.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // Validate the form and show success or error messages
                if (validateForm()) {
                    Toast.makeText(MainActivity.this, "Registration Successful!", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }

    private boolean validateForm() {
        // Get user input values
        String name = edtName.getText().toString().trim();
        String email = edtEmail.getText().toString().trim();
        String password = edtPassword.getText().toString().trim();
        String ageString = edtAge.getText().toString().trim();
        String mobile = edtMobile.getText().toString().trim();

        // Validate Name
        if (TextUtils.isEmpty(name)) {
            edtName.setError("Name is required");
            edtName.requestFocus();
            return false;
        }

        // Validate Email
        if (TextUtils.isEmpty(email) || !Patterns.EMAIL_ADDRESS.matcher(email).matches()) {
            edtEmail.setError("Enter a valid email address");
            edtEmail.requestFocus();
            return false;
        }

        // Validate Password
        if (TextUtils.isEmpty(password) || password.length() < 6) {
            edtPassword.setError("Password must be at least 6 characters");
            edtPassword.requestFocus();
            return false;
        }

        // Validate Age (Should be a valid number)
        if (TextUtils.isEmpty(ageString)) {
            edtAge.setError("Age is required");
            edtAge.requestFocus();
            return false;
        } else {
            try {
                int age = Integer.parseInt(ageString);
                if (age < 18) {
                    edtAge.setError("You must be at least 18 years old");
                    edtAge.requestFocus();
                    return false;
                }
            } catch (NumberFormatException e) {
                edtAge.setError("Invalid age format");
                edtAge.requestFocus();
                return false;
            }
        }

        // Validate Mobile Number
        if (TextUtils.isEmpty(mobile) || mobile.length() != 10) {
            edtMobile.setError("Enter a valid 10-digit mobile number");
            edtMobile.requestFocus();
            return false;
        }

        return true;  // If all validations pass
    }
}

AndroidManifest.xml
-------------------
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.registrationlistview">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="Registration and ListView"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.RegistrationListView">

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>
</manifest>


Design an application for login activity. Write android code to check login credentials with
username = "mca" and password = "android". Display appropriate toast message to the user.

activity_login.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp"
    android:gravity="center">

    <!-- Username Input Field -->
    <EditText
        android:id="@+id/edtUsername"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter Username"
        android:inputType="textPersonName" />

    <!-- Password Input Field -->
    <EditText
        android:id="@+id/edtPassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter Password"
        android:inputType="textPassword"
        android:layout_marginTop="10dp" />

    <!-- Login Button -->
    <Button
        android:id="@+id/btnLogin"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Login"
        android:layout_marginTop="20dp" />

</LinearLayout>
LoginActivity.java
------------------
package com.example.loginapp;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

public class LoginActivity extends AppCompatActivity {

    // Predefined username and password
    private static final String USERNAME = "mca";
    private static final String PASSWORD = "android";

    private EditText edtUsername, edtPassword;
    private Button btnLogin;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        // Initialize the views
        edtUsername = findViewById(R.id.edtUsername);
        edtPassword = findViewById(R.id.edtPassword);
        btnLogin = findViewById(R.id.btnLogin);

        // Set up the login button click listener
        btnLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // Get the username and password entered by the user
                String username = edtUsername.getText().toString().trim();
                String password = edtPassword.getText().toString().trim();

                // Check if the entered credentials match the predefined ones
                if (username.equals(USERNAME) && password.equals(PASSWORD)) {
                    // Display a success message
                    Toast.makeText(LoginActivity.this, "Login Successful!", Toast.LENGTH_SHORT).show();
                } else {
                    // Display an error message
                    Toast.makeText(LoginActivity.this, "Invalid Username or Password", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }
}

AndroidManifest.xml:
--------------------
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.loginapp">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="Login App"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.LoginApp">

        <activity android:name=".LoginActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>

</manifest>


Create the simple calculator shown below also perform appropriate operation.
activity_main.xml
-----------------
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp"
    android:gravity="center">

    <!-- Display Result -->
    <EditText
        android:id="@+id/edtResult"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:inputType="none"
        android:textSize="30sp"
        android:gravity="end"
        android:focusable="false"
        android:layout_marginBottom="20dp"
        android:background="@android:drawable/edit_text"
        android:text="0" />

    <!-- Calculator Buttons (Numbers + Operations) -->
    <GridLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:columnCount="4"
        android:orientation="horizontal">

        <!-- Row 1 -->
        <Button
            android:id="@+id/btn1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="1"
            android:textSize="20sp" />
        <Button
            android:id="@+id/btn2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="2"
            android:textSize="20sp" />
        <Button
            android:id="@+id/btn3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="3"
            android:textSize="20sp" />
        <Button
            android:id="@+id/btnAdd"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="+"
            android:textSize="20sp" />

        <!-- Row 2 -->
        <Button
            android:id="@+id/btn4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="4"
            android:textSize="20sp" />
        <Button
            android:id="@+id/btn5"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="5"
            android:textSize="20sp" />
        <Button
            android:id="@+id/btn6"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="6"
            android:textSize="20sp" />
        <Button
            android:id="@+id/btnSub"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="-"
            android:textSize="20sp" />

        <!-- Row 3 -->
        <Button
            android:id="@+id/btn7"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="7"
            android:textSize="20sp" />
        <Button
            android:id="@+id/btn8"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="8"
            android:textSize="20sp" />
        <Button
            android:id="@+id/btn9"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="9"
            android:textSize="20sp" />
        <Button
            android:id="@+id/btnMul"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="*"
            android:textSize="20sp" />

        <!-- Row 4 -->
        <Button
            android:id="@+id/btn0"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="0"
            android:textSize="20sp" />
        <Button
            android:id="@+id/btnClear"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="C"
            android:textSize="20sp" />
        <Button
            android:id="@+id/btnEqual"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="="
            android:textSize="20sp" />
        <Button
            android:id="@+id/btnDiv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="/"
            android:textSize="20sp" />

    </GridLayout>
</LinearLayout>

MainActivity.java
------------------
package com.example.simplecalculator;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private EditText edtResult;
    private String currentInput = "";
    private String operator = "";
    private double firstOperand = 0;
    private double secondOperand = 0;
    private boolean isOperatorClicked = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize the EditText and Buttons
        edtResult = findViewById(R.id.edtResult);

        Button btn1 = findViewById(R.id.btn1);
        Button btn2 = findViewById(R.id.btn2);
        Button btn3 = findViewById(R.id.btn3);
        Button btn4 = findViewById(R.id.btn4);
        Button btn5 = findViewById(R.id.btn5);
        Button btn6 = findViewById(R.id.btn6);
        Button btn7 = findViewById(R.id.btn7);
        Button btn8 = findViewById(R.id.btn8);
        Button btn9 = findViewById(R.id.btn9);
        Button btn0 = findViewById(R.id.btn0);
        Button btnAdd = findViewById(R.id.btnAdd);
        Button btnSub = findViewById(R.id.btnSub);
        Button btnMul = findViewById(R.id.btnMul);
        Button btnDiv = findViewById(R.id.btnDiv);
        Button btnClear = findViewById(R.id.btnClear);
        Button btnEqual = findViewById(R.id.btnEqual);

        // Set OnClickListeners for the number buttons
        btn1.setOnClickListener(v -> appendToInput("1"));
        btn2.setOnClickListener(v -> appendToInput("2"));
        btn3.setOnClickListener(v -> appendToInput("3"));
        btn4.setOnClickListener(v -> appendToInput("4"));
        btn5.setOnClickListener(v -> appendToInput("5"));
        btn6.setOnClickListener(v -> appendToInput("6"));
        btn7.setOnClickListener(v -> appendToInput("7"));
        btn8.setOnClickListener(v -> appendToInput("8"));
        btn9.setOnClickListener(v -> appendToInput("9"));
        btn0.setOnClickListener(v -> appendToInput("0"));

        // Set OnClickListeners for operator buttons
        btnAdd.setOnClickListener(v -> handleOperator("+"));
        btnSub.setOnClickListener(v -> handleOperator("-"));
        btnMul.setOnClickListener(v -> handleOperator("*"));
        btnDiv.setOnClickListener(v -> handleOperator("/"));

        // Set OnClickListener for the clear button
        btnClear.setOnClickListener(v -> clearInput());

        // Set OnClickListener for the equal button to perform calculation
        btnEqual.setOnClickListener(v -> calculateResult());
    }

    // Method to append numbers to the input
    private void appendToInput(String value) {
        currentInput += value;
        edtResult.setText(currentInput);
    }

    // Method to handle operator buttons (+, -, *, /)
    private void handleOperator(String operator) {
        if (currentInput.isEmpty()) return;

        this.operator = operator;
        firstOperand = Double.parseDouble(currentInput);
        currentInput = "";
        edtResult.setText("");
    }

    // Method to clear the input
    private void clearInput() {
        currentInput = "";
        edtResult.setText("");
        operator = "";
        firstOperand = 0;
        secondOperand = 0;
    }

    // Method to calculate the result
    private void calculateResult() {
        if (currentInput.isEmpty()) return;

        secondOperand = Double.parseDouble(currentInput);

        double result = 0;
        switch (operator) {
            case "+":
                result = firstOperand + secondOperand;
                break;
            case "-":
                result = firstOperand - secondOperand;
                break;
            case "*":
                result = firstOperand * secondOperand;
                break;
            case "/":
                if (secondOperand == 0) {
                    Toast.makeText(this, "Cannot divide by zero", Toast.LENGTH_SHORT).show();
                    return;
                }
                result = firstOperand / secondOperand;
                break;
            default:
                return;
        }

        // Display the result in the EditText
        edtResult.setText(String.valueOf(result));
        currentInput = String.valueOf(result); // Allow for continuing operations with the result
        operator = "";
    }
}

Create an Android Application to find the factorial of a number and Display the Result on alert

activity_main.xml
-----------------
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp"
    android:gravity="center">

    <!-- Input field for number -->
    <EditText
        android:id="@+id/edtNumber"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter a number"
        android:inputType="number"
        android:textSize="18sp"
        android:layout_marginBottom="20dp"/>

    <!-- Button to calculate factorial -->
    <Button
        android:id="@+id/btnCalculate"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Calculate Factorial"
        android:textSize="18sp" />

</LinearLayout>

MainActivity.java
-----------------
package com.example.factorialapp;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private EditText edtNumber;
    private Button btnCalculate;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize the views
        edtNumber = findViewById(R.id.edtNumber);
        btnCalculate = findViewById(R.id.btnCalculate);

        // Set up the button click listener
        btnCalculate.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // Get the number from the EditText
                String input = edtNumber.getText().toString();

                // Check if the input is empty
                if (input.isEmpty()) {
                    Toast.makeText(MainActivity.this, "Please enter a number", Toast.LENGTH_SHORT).show();
                    return;
                }

                try {
                    // Parse the input number
                    int number = Integer.parseInt(input);

                    // Check if the number is negative
                    if (number < 0) {
                        Toast.makeText(MainActivity.this, "Please enter a non-negative number", Toast.LENGTH_SHORT).show();
                        return;
                    }

                    // Calculate the factorial
                    long factorial = calculateFactorial(number);

                    // Display the result in an AlertDialog
                    showResult(factorial);

                } catch (NumberFormatException e) {
                    Toast.makeText(MainActivity.this, "Invalid input. Please enter a valid number", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }

    // Method to calculate the factorial of a number
    private long calculateFactorial(int number) {
        long result = 1;
        for (int i = 1; i <= number; i++) {
            result *= i;
        }
        return result;
    }

    // Method to show the result in an AlertDialog
    private void showResult(long factorial) {
        // Create an AlertDialog to display the factorial
        AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
        builder.setTitle("Factorial Result")
                .setMessage("The factorial is: " + factorial)
                .setPositiveButton("OK", null)
                .show();
    }
}

AndroidManifest.xml
-------------------
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.factorialapp">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="Factorial App"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.FactorialApp">

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>

</manifest>

Create an application that allows the user to enter a number in the textbox. Check whether the
number in the textbox is Armstrong or not. Print the message accordingly in the label control.

activity_main.xml
-----------------
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp"
    android:gravity="center">

    <!-- Input field for number -->
    <EditText
        android:id="@+id/edtNumber"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter a number"
        android:inputType="number"
        android:textSize="18sp"
        android:layout_marginBottom="20dp"/>

    <!-- Button to check Armstrong number -->
    <Button
        android:id="@+id/btnCheck"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Check Armstrong"
        android:textSize="18sp" />

    <!-- TextView to display result -->
    <TextView
        android:id="@+id/tvResult"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Result will appear here"
        android:textSize="18sp"
        android:layout_marginTop="20dp"
        android:textColor="#000000"/>

</LinearLayout>


MainActivity.java
-----------------
package com.example.armstrongnumber;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private EditText edtNumber;
    private Button btnCheck;
    private TextView tvResult;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize the views
        edtNumber = findViewById(R.id.edtNumber);
        btnCheck = findViewById(R.id.btnCheck);
        tvResult = findViewById(R.id.tvResult);

        // Set the click listener for the button
        btnCheck.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // Get the number from the EditText
                String input = edtNumber.getText().toString();

                // Check if the input is empty
                if (input.isEmpty()) {
                    Toast.makeText(MainActivity.this, "Please enter a number", Toast.LENGTH_SHORT).show();
                    return;
                }

                try {
                    // Parse the number from the input
                    int number = Integer.parseInt(input);

                    // Check if the number is an Armstrong number
                    if (isArmstrong(number)) {
                        tvResult.setText(number + " is an Armstrong number.");
                    } else {
                        tvResult.setText(number + " is NOT an Armstrong number.");
                    }

                } catch (NumberFormatException e) {
                    Toast.makeText(MainActivity.this, "Invalid input. Please enter a valid number.", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }

    // Method to check if a number is an Armstrong number
    private boolean isArmstrong(int number) {
        int sum = 0;
        int originalNumber = number;
        int digits = String.valueOf(number).length();

        // Calculate the sum of the digits raised to the power of the number of digits
        while (number != 0) {
            int digit = number % 10;
            sum += Math.pow(digit, digits);
            number /= 10;
        }

        // Return true if the sum equals the original number
        return sum == originalNumber;
    }
}

AndroidManifest.xml:
-------------------
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.armstrongnumber">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="Armstrong Number Checker"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.AppCompat.DayNight.NoActionBar">

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>

</manifest>

Create an application that demonstrate Options Menu, Context Menu and Popup Menu in
android.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp"
    android:gravity="center">

    <!-- TextView to display selected menu item -->
    <TextView
        android:id="@+id/tvSelectedOption"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Select a menu option"
        android:textSize="18sp"
        android:textColor="#000000"
        android:layout_marginBottom="20dp"/>

    <!-- Button to show options menu -->
    <Button
        android:id="@+id/btnOptionsMenu"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Show Options Menu"
        android:textSize="16sp"/>

    <!-- Button to show context menu -->
    <Button
        android:id="@+id/btnContextMenu"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Show Context Menu"
        android:textSize="16sp"
        android:layout_marginTop="20dp"/>

    <!-- Button to show popup menu -->
    <Button
        android:id="@+id/btnPopupMenu"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Show Popup Menu"
        android:textSize="16sp"
        android:layout_marginTop="20dp"/>

</LinearLayout>

MainActivity.java
------------------
package com.example.menudemo;

import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.view.menu.MenuBuilder;
import androidx.appcompat.widget.PopupMenu;

public class MainActivity extends AppCompatActivity {

    private TextView tvSelectedOption;
    private Button btnOptionsMenu, btnContextMenu, btnPopupMenu;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        tvSelectedOption = findViewById(R.id.tvSelectedOption);
        btnOptionsMenu = findViewById(R.id.btnOptionsMenu);
        btnContextMenu = findViewById(R.id.btnContextMenu);
        btnPopupMenu = findViewById(R.id.btnPopupMenu);

        // Button to show Options Menu
        btnOptionsMenu.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                openOptionsMenu();
            }
        });

        // Button to show Context Menu
        btnContextMenu.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                registerForContextMenu(v);  // Register the view for context menu
                openContextMenu(v);  // Open the context menu for the view
            }
        });

        // Button to show Popup Menu
        btnPopupMenu.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                showPopupMenu(v);
            }
        });
    }

    // Options Menu
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu (options menu)
        getMenuInflater().inflate(R.menu.menu_options, menu);
        return true;
    }

    // Handle item selection from Options Menu
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.menu_item_1:
                tvSelectedOption.setText("Option 1 selected from Options Menu");
                return true;
            case R.id.menu_item_2:
                tvSelectedOption.setText("Option 2 selected from Options Menu");
                return true;
            case R.id.menu_item_3:
                tvSelectedOption.setText("Option 3 selected from Options Menu");
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }

    // Context Menu
    @Override
    public void onCreateContextMenu(android.view.ContextMenu menu, View v, android.view.ContextMenu.ContextMenuInfo menuInfo) {
        super.onCreateContextMenu(menu, v, menuInfo);
        // Inflate the context menu
        getMenuInflater().inflate(R.menu.menu_context, menu);
    }

    // Handle item selection from Context Menu
    @Override
    public boolean onContextItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.context_item_1:
                tvSelectedOption.setText("Option 1 selected from Context Menu");
                return true;
            case R.id.context_item_2:
                tvSelectedOption.setText("Option 2 selected from Context Menu");
                return true;
            case R.id.context_item_3:
                tvSelectedOption.setText("Option 3 selected from Context Menu");
                return true;
            default:
                return super.onContextItemSelected(item);
        }
    }

    // Popup Menu
    private void showPopupMenu(View view) {
        PopupMenu popupMenu = new PopupMenu(MainActivity.this, view);
        getMenuInflater().inflate(R.menu.menu_popup, popupMenu.getMenu());

        // Set the listener for PopupMenu items
        popupMenu.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
            @Override
            public boolean onMenuItemClick(MenuItem item) {
                switch (item.getItemId()) {
                    case R.id.popup_item_1:
                        tvSelectedOption.setText("Option 1 selected from Popup Menu");
                        return true;
                    case R.id.popup_item_2:
                        tvSelectedOption.setText("Option 2 selected from Popup Menu");
                        return true;
                    case R.id.popup_item_3:
                        tvSelectedOption.setText("Option 3 selected from Popup Menu");
                        return true;
                    default:
                        return false;
                }
            }
        });
        popupMenu.show();
    }
}

menu_options.xml (for Options Menu)
-----------------------------------
Create this file in the res/menu/ folder.
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/menu_item_1"
        android:title="Option 1"/>
    <item
        android:id="@+id/menu_item_2"
        android:title="Option 2"/>
    <item
        android:id="@+id/menu_item_3"
        android:title="Option 3"/>
</menu>
menu_context.xml (for Context Menu)
Create this file in the res/menu/ folder.
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/context_item_1"
        android:title="Context Option 1"/>
    <item
        android:id="@+id/context_item_2"
        android:title="Context Option 2"/>
    <item
        android:id="@+id/context_item_3"
        android:title="Context Option 3"/>
</menu>
menu_popup.xml (for Popup Menu)
Create this file in the res/menu/ folder.
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/popup_item_1"
        android:title="Popup Option 1"/>
    <item
        android:id="@+id/popup_item_2"
        android:title="Popup Option 2"/>
    <item
        android:id="@+id/popup_item_3"
        android:title="Popup Option 3"/>
</menu>
AndroidManifest.xml
------------------
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.menudemo">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="Menu Demo"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.AppCompat.DayNight.NoActionBar">

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>

</manifest>

Create the following Vertical Scroll View Creation in Android.
activity_main.xml
-----------------
<?xml version="1.0" encoding="utf-8"?>
<androidx.core.widget.NestedScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fillViewport="true">

    <!-- LinearLayout to contain the buttons -->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:padding="16dp">

        <!-- Button 1 -->
        <Button
            android:id="@+id/button1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Button 1" />

        <!-- Button 2 -->
        <Button
            android:id="@+id/button2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Button 2" />

        <!-- Button 3 -->
        <Button
            android:id="@+id/button3"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Button 3" />

        <!-- Button 4 -->
        <Button
            android:id="@+id/button4"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Button 4" />

        <!-- Button 5 -->
        <Button
            android:id="@+id/button5"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Button 5" />

        <!-- Button 6 -->
        <Button
            android:id="@+id/button6"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Button 6" />

        <!-- Button 7 -->
        <Button
            android:id="@+id/button7"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Button 7" />

        <!-- Button 8 -->
        <Button
            android:id="@+id/button8"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Button 8" />

    </LinearLayout>
</androidx.core.widget.NestedScrollView>

MainActivity.java
-----------------
package com.example.scrollviewdemo;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize buttons
        Button button1 = findViewById(R.id.button1);
        Button button2 = findViewById(R.id.button2);
        Button button3 = findViewById(R.id.button3);
        Button button4 = findViewById(R.id.button4);
        Button button5 = findViewById(R.id.button5);
        Button button6 = findViewById(R.id.button6);
        Button button7 = findViewById(R.id.button7);
        Button button8 = findViewById(R.id.button8);

        // Set click listeners for buttons
        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "Button 1 clicked", Toast.LENGTH_SHORT).show();
            }
        });

        button2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "Button 2 clicked", Toast.LENGTH_SHORT).show();
            }
        });

        button3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "Button 3 clicked", Toast.LENGTH_SHORT).show();
            }
        });

        button4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "Button 4 clicked", Toast.LENGTH_SHORT).show();
            }
        });

        button5.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "Button 5 clicked", Toast.LENGTH_SHORT).show();
            }
        });

        button6.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "Button 6 clicked", Toast.LENGTH_SHORT).show();
            }
        });

        button7.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "Button 7 clicked", Toast.LENGTH_SHORT).show();
            }
        });

        button8.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "Button 8 clicked", Toast.LENGTH_SHORT).show();
            }
        });
    }
}

AndroidManifest.xml
-------------------
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.scrollviewdemo">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="ScrollView Demo"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.AppCompat.DayNight.NoActionBar">

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>

</manifest>



Create First Activity to accept information like Employee First Name, Middle Name, Last Name, Date of
birth, Address, Email ID and display all information on Second Activity when user click on Submit button.
XML Layout (activity_main.xml)
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <!-- Employee First Name -->
    <EditText
        android:id="@+id/edtFirstName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="First Name"
        android:inputType="textPersonName" />

    <!-- Employee Middle Name -->
    <EditText
        android:id="@+id/edtMiddleName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Middle Name"
        android:inputType="textPersonName" />

    <!-- Employee Last Name -->
    <EditText
        android:id="@+id/edtLastName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Last Name"
        android:inputType="textPersonName" />

    <!-- Employee Date of Birth -->
    <EditText
        android:id="@+id/edtDateOfBirth"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Date of Birth (yyyy-mm-dd)"
        android:inputType="date" />

    <!-- Employee Address -->
    <EditText
        android:id="@+id/edtAddress"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Address"
        android:inputType="textMultiLine" />

    <!-- Employee Email -->
    <EditText
        android:id="@+id/edtEmail"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Email"
        android:inputType="textEmailAddress" />

    <!-- Submit Button -->
    <Button
        android:id="@+id/btnSubmit"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Submit" />

</LinearLayout>
Java Code for MainActivity
In this MainActivity.java, we will capture the employee data from the EditText fields, and pass it to the second activity using an Intent.

package com.example.employeeinfo;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    // Declare UI elements
    private EditText edtFirstName, edtMiddleName, edtLastName, edtDateOfBirth, edtAddress, edtEmail;
    private Button btnSubmit;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize UI elements
        edtFirstName = findViewById(R.id.edtFirstName);
        edtMiddleName = findViewById(R.id.edtMiddleName);
        edtLastName = findViewById(R.id.edtLastName);
        edtDateOfBirth = findViewById(R.id.edtDateOfBirth);
        edtAddress = findViewById(R.id.edtAddress);
        edtEmail = findViewById(R.id.edtEmail);
        btnSubmit = findViewById(R.id.btnSubmit);

        // Set click listener on submit button
        btnSubmit.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // Get the values from the EditText fields
                String firstName = edtFirstName.getText().toString();
                String middleName = edtMiddleName.getText().toString();
                String lastName = edtLastName.getText().toString();
                String dateOfBirth = edtDateOfBirth.getText().toString();
                String address = edtAddress.getText().toString();
                String email = edtEmail.getText().toString();

                // Check if any field is empty
                if (firstName.isEmpty() || middleName.isEmpty() || lastName.isEmpty() || dateOfBirth.isEmpty() || address.isEmpty() || email.isEmpty()) {
                    Toast.makeText(MainActivity.this, "Please fill all fields", Toast.LENGTH_SHORT).show();
                } else {
                    // Create an Intent to send data to SecondActivity
                    Intent intent = new Intent(MainActivity.this, SecondActivity.class);
                    intent.putExtra("first_name", firstName);
                    intent.putExtra("middle_name", middleName);
                    intent.putExtra("last_name", lastName);
                    intent.putExtra("date_of_birth", dateOfBirth);
                    intent.putExtra("address", address);
                    intent.putExtra("email", email);

                    // Start the Second Activity
                    startActivity(intent);
                }
            }
        });
    }
}
XML Layout (activity_second.xml) for Second Activity
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <!-- TextViews to display the employee information -->
    <TextView
        android:id="@+id/tvFirstName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="First Name: "
        android:textSize="18sp" />

    <TextView
        android:id="@+id/tvMiddleName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Middle Name: "
        android:textSize="18sp" />

    <TextView
        android:id="@+id/tvLastName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Last Name: "
        android:textSize="18sp" />

    <TextView
        android:id="@+id/tvDateOfBirth"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Date of Birth: "
        android:textSize="18sp" />

    <TextView
        android:id="@+id/tvAddress"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Address: "
        android:textSize="18sp" />

    <TextView
        android:id="@+id/tvEmail"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Email: "
        android:textSize="18sp" />

</LinearLayout>
Java Code for SecondActivity.java
package com.example.employeeinfo;

import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;

public class SecondActivity extends AppCompatActivity {

    // Declare TextViews to display employee information
    private TextView tvFirstName, tvMiddleName, tvLastName, tvDateOfBirth, tvAddress, tvEmail;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);

        // Initialize TextViews
        tvFirstName = findViewById(R.id.tvFirstName);
        tvMiddleName = findViewById(R.id.tvMiddleName);
        tvLastName = findViewById(R.id.tvLastName);
        tvDateOfBirth = findViewById(R.id.tvDateOfBirth);
        tvAddress = findViewById(R.id.tvAddress);
        tvEmail = findViewById(R.id.tvEmail);

        // Get the Intent that started this activity
        Intent intent = getIntent();

        // Retrieve the employee data from the Intent
        String firstName = intent.getStringExtra("first_name");
        String middleName = intent.getStringExtra("middle_name");
        String lastName = intent.getStringExtra("last_name");
        String dateOfBirth = intent.getStringExtra("date_of_birth");
        String address = intent.getStringExtra("address");
        String email = intent.getStringExtra("email");

        // Display the employee data on the TextViews
        tvFirstName.setText("First Name: " + firstName);
        tvMiddleName.setText("Middle Name: " + middleName);
        tvLastName.setText("Last Name: " + lastName);
        tvDateOfBirth.setText("Date of Birth: " + dateOfBirth);
        tvAddress.setText("Address: " + address);
        tvEmail.setText("Email: " + email);
    }
}
AndroidManifest.xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.employeeinfo">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="Employee Info"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.AppCompat.DayNight.NoActionBar">

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity android:name=".SecondActivity" />
    </application>

</manifest>


Create application to send an email.

activity_main.xml
-----------------
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <EditText
        android:id="@+id/edtRecipient"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Recipient Email"
        android:inputType="textEmailAddress"/>

    <EditText
        android:id="@+id/edtSubject"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Subject"
        android:inputType="text"/>

    <EditText
        android:id="@+id/edtBody"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Message Body"
        android:inputType="textMultiLine"
        android:lines="5"
        android:gravity="top|start"/>

    <Button
        android:id="@+id/btnSendEmail"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Send Email"/>

</LinearLayout>

MainActivity.java
------------------
package com.example.sendemailapp;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private EditText edtRecipient, edtSubject, edtBody;
    private Button btnSendEmail;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        edtRecipient = findViewById(R.id.edtRecipient);
        edtSubject = findViewById(R.id.edtSubject);
        edtBody = findViewById(R.id.edtBody);
        btnSendEmail = findViewById(R.id.btnSendEmail);

        btnSendEmail.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String recipient = edtRecipient.getText().toString();
                String subject = edtSubject.getText().toString();
                String body = edtBody.getText().toString();

                if (recipient.isEmpty() || subject.isEmpty() || body.isEmpty()) {
                    Toast.makeText(MainActivity.this, "Please fill in all fields", Toast.LENGTH_SHORT).show();
                } else {
                    Intent intent = new Intent(Intent.ACTION_SEND);
                    intent.setType("message/rfc822");
                    intent.putExtra(Intent.EXTRA_EMAIL, new String[]{recipient});
                    intent.putExtra(Intent.EXTRA_SUBJECT, subject);
                    intent.putExtra(Intent.EXTRA_TEXT, body);

                    try {
                        startActivity(Intent.createChooser(intent, "Choose an email client"));
                    } catch (android.content.ActivityNotFoundException ex) {
                        Toast.makeText(MainActivity.this, "No email client found", Toast.LENGTH_SHORT).show();
                    }
                }
            }
        });
    }
}

AndroidManifest.xml
-------------------
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.sendemailapp">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="Send Email App"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.AppCompat.DayNight.NoActionBar">

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>

</manifest>

Create sample application with login module. Verify Check username and password. On
successful login, pass username to next screen and if login fails, prompt the user.

activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <EditText
        android:id="@+id/edtUsername"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Username"
        android:inputType="text"/>

    <EditText
        android:id="@+id/edtPassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Password"
        android:inputType="textPassword"/>

    <Button
        android:id="@+id/btnLogin"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Login"/>

    <TextView
        android:id="@+id/tvError"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text=""
        android:textColor="#FF0000"
        android:visibility="gone"/>
</LinearLayout>
activity_dashboard.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <TextView
        android:id="@+id/tvWelcome"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Welcome!"
        android:textSize="20sp"/>

</LinearLayout>
MainActivity.java
package com.example.loginapp;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private EditText edtUsername, edtPassword;
    private Button btnLogin;
    private TextView tvError;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        edtUsername = findViewById(R.id.edtUsername);
        edtPassword = findViewById(R.id.edtPassword);
        btnLogin = findViewById(R.id.btnLogin);
        tvError = findViewById(R.id.tvError);

        btnLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String username = edtUsername.getText().toString();
                String password = edtPassword.getText().toString();

                if (username.equals("user") && password.equals("password123")) {
                    Intent intent = new Intent(MainActivity.this, DashboardActivity.class);
                    intent.putExtra("username", username);
                    startActivity(intent);
                    finish();
                } else {
                    tvError.setVisibility(View.VISIBLE);
                    tvError.setText("Invalid username or password");
                }
            }
        });
    }
}
DashboardActivity.java
package com.example.loginapp;

import android.os.Bundle;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;

public class DashboardActivity extends AppCompatActivity {

    private TextView tvWelcome;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_dashboard);

        tvWelcome = findViewById(R.id.tvWelcome);

        String username = getIntent().getStringExtra("username");
        if (username != null) {
            tvWelcome.setText("Welcome, " + username + "!");
        }
    }
}
AndroidManifest.xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.loginapp">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="LoginApp"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.AppCompat.DayNight.NoActionBar">

        <activity android:name=".DashboardActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity android:name=".MainActivity"/>
    </application>

</manifest>


Create a Simple Application, which reads a positive number from the user and display its
factorial value in another activity.

activity_main.xml (Main Activity Layout)
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <EditText
        android:id="@+id/edtNumber"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter a positive number"
        android:inputType="number"/>

    <Button
        android:id="@+id/btnCalculate"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Calculate Factorial"/>

</LinearLayout>
activity_result.xml (Result Activity Layout)
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp"
    android:gravity="center">

    <TextView
        android:id="@+id/tvResult"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Factorial Result"
        android:textSize="20sp"/>
</LinearLayout>
MainActivity.java (Main Activity Logic)
package com.example.factorialapp;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private EditText edtNumber;
    private Button btnCalculate;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        edtNumber = findViewById(R.id.edtNumber);
        btnCalculate = findViewById(R.id.btnCalculate);

        btnCalculate.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String input = edtNumber.getText().toString();
                if (!input.isEmpty()) {
                    int number = Integer.parseInt(input);
                    if (number >= 0) {
                        // Calculate factorial and pass to the ResultActivity
                        long factorialResult = calculateFactorial(number);
                        Intent intent = new Intent(MainActivity.this, ResultActivity.class);
                        intent.putExtra("factorial", factorialResult);
                        startActivity(intent);
                    } else {
                        Toast.makeText(MainActivity.this, "Please enter a positive number", Toast.LENGTH_SHORT).show();
                    }
                } else {
                    Toast.makeText(MainActivity.this, "Please enter a number", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }

    private long calculateFactorial(int number) {
        long result = 1;
        for (int i = 1; i <= number; i++) {
            result *= i;
        }
        return result;
    }
}
ResultActivity.java (Result Activity Logic)
package com.example.factorialapp;

import android.os.Bundle;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;

public class ResultActivity extends AppCompatActivity {

    private TextView tvResult;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_result);

        tvResult = findViewById(R.id.tvResult);

        // Get factorial result from Intent
        long factorial = getIntent().getLongExtra("factorial", -1);
        if (factorial != -1) {
            tvResult.setText("Factorial: " + factorial);
        }
    }
}
AndroidManifest.xml (Manifest File)
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.factorialapp">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="FactorialApp"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.AppCompat.DayNight.NoActionBar">

        <activity android:name=".ResultActivity" />
        
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>
</manifest>
build.gradle (app level)
Make sure you have the appropriate dependencies set for the app.
dependencies {
    implementation 'androidx.appcompat:appcompat:1.2.0'
}


Create a simple To-Do List Application using React JS.

To install:
npx create-react-app todo-app
Once the app is created, navigate to the todo-app folder:
cd todo-app
2. App.js (Main Application File)

import React, { useState } from 'react';
import './App.css';

function App() {
  // State for storing tasks
  const [task, setTask] = useState("");
  const [todos, setTodos] = useState([]);

  // Add new task to the list
  const handleAddTask = () => {
    if (task.trim() !== "") {
      setTodos([
        ...todos,
        { id: Date.now(), text: task, completed: false }
      ]);
      setTask("");
    }
  };

  // Mark task as completed
  const toggleComplete = (id) => {
    setTodos(todos.map(todo => 
      todo.id === id ? { ...todo, completed: !todo.completed } : todo
    ));
  };

  // Delete task
  const deleteTask = (id) => {
    setTodos(todos.filter(todo => todo.id !== id));
  };

  return (
    <div className="App">
      <h1>To-Do List</h1>
      
      {/* Input field for new task */}
      <input 
        type="text" 
        value={task} 
        onChange={(e) => setTask(e.target.value)} 
        placeholder="Enter a task"
      />
      
      {/* Add Task Button */}
      <button onClick={handleAddTask}>Add Task</button>

      <ul>
        {todos.map(todo => (
          <li key={todo.id} style={{ textDecoration: todo.completed ? 'line-through' : 'none' }}>
            <span onClick={() => toggleComplete(todo.id)}>{todo.text}</span>
            <button onClick={() => deleteTask(todo.id)}>Delete</button>
          </li>
        ))}
      </ul>
    </div>
  );
}

export default App;
3. App.css (Styling the To-Do List)
.App {
  font-family: Arial, sans-serif;
  width: 300px;
  margin: 0 auto;
  text-align: center;
}

h1 {
  color: #4CAF50;
}

input {
  width: 70%;
  padding: 10px;
  margin-bottom: 10px;
  margin-right: 5px;
}

button {
  padding: 10px;
  background-color: #4CAF50;
  color: white;
  border: none;
  cursor: pointer;
}

button:hover {
  background-color: #45a049;
}

ul {
  list-style-type: none;
  padding: 0;
}

li {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin: 10px 0;
}

li button {
  background-color: red;
  color: white;
  padding: 5px 10px;
  border: none;
  cursor: pointer;
}

li button:hover {
  background-color: darkred;
}

span {
  cursor: pointer;
}

To start enter the command :  npm start


Create an Android Application that Demonstrate Radio Button.

. Layout File (activity_main.xml)
The layout will have a group of radio buttons inside a RadioGroup, and a TextView to display the selected option.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <!-- Title Text -->
    <TextView
        android:id="@+id/tvTitle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Select Your Favorite Fruit"
        android:textSize="20sp"
        android:layout_marginBottom="16dp" />

    <!-- RadioGroup to contain multiple RadioButtons -->
    <RadioGroup
        android:id="@+id/radioGroup"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <!-- Radio Buttons -->
        <RadioButton
            android:id="@+id/radioApple"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Apple" />

        <RadioButton
            android:id="@+id/radioBanana"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Banana" />

        <RadioButton
            android:id="@+id/radioCherry"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Cherry" />
    </RadioGroup>

    <!-- TextView to show the selected fruit -->
    <TextView
        android:id="@+id/tvResult"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Selected Fruit: None"
        android:textSize="18sp"
        android:layout_marginTop="16dp" />
</LinearLayout>
2. MainActivity.java
In this activity, we will handle the selection of the radio buttons and update the TextView based on the user's choice.
package com.example.radiobuttonapp;

import android.os.Bundle;
import android.view.View;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private RadioGroup radioGroup;
    private RadioButton radioApple, radioBanana, radioCherry;
    private TextView tvResult;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize UI components
        radioGroup = findViewById(R.id.radioGroup);
        radioApple = findViewById(R.id.radioApple);
        radioBanana = findViewById(R.id.radioBanana);
        radioCherry = findViewById(R.id.radioCherry);
        tvResult = findViewById(R.id.tvResult);

        // Set listener for the RadioGroup
        radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup group, int checkedId) {
                // Check which radio button is selected
                if (checkedId == R.id.radioApple) {
                    tvResult.setText("Selected Fruit: Apple");
                } else if (checkedId == R.id.radioBanana) {
                    tvResult.setText("Selected Fruit: Banana");
                } else if (checkedId == R.id.radioCherry) {
                    tvResult.setText("Selected Fruit: Cherry");
                }
            }
        });
    }
}
3. AndroidManifest.xml
Make sure the MainActivity is declared in the AndroidManifest.xml.

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.radiobuttonapp">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="RadioButtonApp"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.AppCompat.DayNight.NoActionBar">

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>
</manifest>


Create an Android Application that Demonstrate Switch and Toggle Button.
(activity_main.xml)
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp"
    android:gravity="center">

    <!-- TextView to show the status -->
    <TextView
        android:id="@+id/statusTextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Switch and ToggleButton Status"
        android:textSize="18sp"
        android:layout_marginBottom="20dp"
        android:layout_marginTop="20dp"/>

    <!-- Switch -->
    <Switch
        android:id="@+id/switchButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Switch"
        android:layout_marginBottom="20dp" />

    <!-- ToggleButton -->
    <ToggleButton
        android:id="@+id/toggleButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textOn="ON"
        android:textOff="OFF"
        android:layout_marginBottom="20dp"/>

</LinearLayout>
MainActivity.java
package com.example.switchtogglebuttondemo;

import android.os.Bundle;
import android.view.View;
import android.widget.Switch;
import android.widget.TextView;
import android.widget.ToggleButton;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private Switch switchButton;
    private ToggleButton toggleButton;
    private TextView statusTextView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize UI components
        switchButton = findViewById(R.id.switchButton);
        toggleButton = findViewById(R.id.toggleButton);
        statusTextView = findViewById(R.id.statusTextView);

        // Set listeners for Switch and ToggleButton
        switchButton.setOnCheckedChangeListener((buttonView, isChecked) -> updateStatus());
        toggleButton.setOnCheckedChangeListener((buttonView, isChecked) -> updateStatus());
    }

    // Method to update the status TextView based on Switch and ToggleButton states
    private void updateStatus() {
        String switchStatus = switchButton.isChecked() ? "ON" : "OFF";
        String toggleStatus = toggleButton.isChecked() ? "ON" : "OFF";

        String statusText = "Switch is " + switchStatus + "\n" +
                            "ToggleButton is " + toggleStatus;
        statusTextView.setText(statusText);
    }
}

Create a custom "Contact" layout to hold multiple pieces of information, including: Photo,
Name, Contact Number, E-mail id.
Contact Item Layout (contact_item.xml)
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:padding="16dp"
    android:background="?android:attr/selectableItemBackground">

    <!-- ImageView for contact photo -->
    <ImageView
        android:id="@+id/contactPhoto"
        android:layout_width="60dp"
        android:layout_height="60dp"
        android:src="@drawable/ic_person"  <!-- Default image (use any drawable) -->
        android:layout_marginEnd="16dp"
        android:contentDescription="Contact Photo"/>

    <!-- Vertical LinearLayout for name, number, and email -->
    <LinearLayout
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:layout_weight="1">

        <!-- TextView for contact name -->
        <TextView
            android:id="@+id/contactName"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="John Doe"
            android:textSize="18sp"
            android:textStyle="bold"/>

        <!-- TextView for contact number -->
        <TextView
            android:id="@+id/contactNumber"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="123-456-7890"
            android:textSize="16sp"
            android:textColor="#888"/>

        <!-- TextView for contact email -->
        <TextView
            android:id="@+id/contactEmail"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="email@example.com"
            android:textSize="16sp"
            android:textColor="#888"/>
    </LinearLayout>
</LinearLayout>
Model Class (Contact.java)
package com.example.contactapp;

public class Contact {
    private String photoUrl;  // URL or Drawable resource for photo
    private String name;
    private String contactNumber;
    private String email;

    // Constructor
    public Contact(String photoUrl, String name, String contactNumber, String email) {
        this.photoUrl = photoUrl;
        this.name = name;
        this.contactNumber = contactNumber;
        this.email = email;
    }

    // Getters and setters
    public String getPhotoUrl() {
        return photoUrl;
    }

    public void setPhotoUrl(String photoUrl) {
        this.photoUrl = photoUrl;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getContactNumber() {
        return contactNumber;
    }

    public void setContactNumber(String contactNumber) {
        this.contactNumber = contactNumber;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }
}
RecyclerView Adapter (ContactAdapter.java)
The adapter will bind the Contact data to the views in the contact_item.xml.
package com.example.contactapp;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.recyclerview.widget.RecyclerView;
import com.bumptech.glide.Glide;  // For loading images from URLs

import java.util.List;

public class ContactAdapter extends RecyclerView.Adapter<ContactAdapter.ContactViewHolder> {

    private List<Contact> contactList;

    public ContactAdapter(List<Contact> contactList) {
        this.contactList = contactList;
    }

    @Override
    public ContactViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.contact_item, parent, false);
        return new ContactViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ContactViewHolder holder, int position) {
        Contact contact = contactList.get(position);

        // Set the contact's name, number, and email
        holder.nameTextView.setText(contact.getName());
        holder.numberTextView.setText(contact.getContactNumber());
        holder.emailTextView.setText(contact.getEmail());

        // Load the contact's photo (using Glide to handle image loading)
        Glide.with(holder.itemView.getContext())
                .load(contact.getPhotoUrl())  // This could be a URL or drawable resource
                .into(holder.photoImageView);
    }

    @Override
    public int getItemCount() {
        return contactList.size();
    }

    public static class ContactViewHolder extends RecyclerView.ViewHolder {
        ImageView photoImageView;
        TextView nameTextView, numberTextView, emailTextView;

        public ContactViewHolder(View itemView) {
            super(itemView);
            photoImageView = itemView.findViewById(R.id.contactPhoto);
            nameTextView = itemView.findViewById(R.id.contactName);
            numberTextView = itemView.findViewById(R.id.contactNumber);
            emailTextView = itemView.findViewById(R.id.contactEmail);
        }
    }
}
MainActivity (MainActivity.java)
In the MainActivity, we will set up a RecyclerView to display the list of contacts.
package com.example.contactapp;

import android.os.Bundle;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private RecyclerView recyclerView;
    private ContactAdapter contactAdapter;
    private List<Contact> contactList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        recyclerView = findViewById(R.id.recyclerView);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));

        // Initialize contact list
        contactList = new ArrayList<>();
        loadContacts();

        // Set up the adapter for the RecyclerView
        contactAdapter = new ContactAdapter(contactList);
        recyclerView.setAdapter(contactAdapter);
    }

    private void loadContacts() {
        // Adding some sample contacts
        contactList.add(new Contact("https://example.com/photo1.jpg", "John Doe", "123-456-7890", "john.doe@example.com"));
        contactList.add(new Contact("https://example.com/photo2.jpg", "Jane Smith", "987-654-3210", "jane.smith@example.com"));
        contactList.add(new Contact("https://example.com/photo3.jpg", "Emma Brown", "555-555-5555", "emma.brown@example.com"));
    }
}
Layout for MainActivity (activity_main.xml)
We will use a RecyclerView to display the list of contacts in the main activity.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</LinearLayout>
Gradle Dependencies (for Glide)
If you're using Glide to load images from URLs, you need to add Glide to your project by adding this dependency in your build.gradle file.

dependencies {
    implementation 'com.github.bumptech.glide:glide:4.12.0'
    annotationProcessor 'com.github.bumptech.glide:compiler:4.12.0'
}

Create an application to demonstrate date and time picker?

activity_main.xml
In the layout file, we'll have two buttons, one to pick a date and the other to pick a time, and TextViews to display the selected date and time.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp"
    android:gravity="center">

    <!-- Button to open Date Picker -->
    <Button
        android:id="@+id/btnDate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Pick Date" />

    <!-- TextView to display the selected date -->
    <TextView
        android:id="@+id/tvSelectedDate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Selected Date: "
        android:textSize="18sp"
        android:layout_marginTop="16dp"/>

    <!-- Button to open Time Picker -->
    <Button
        android:id="@+id/btnTime"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Pick Time"
        android:layout_marginTop="16dp"/>

    <!-- TextView to display the selected time -->
    <TextView
        android:id="@+id/tvSelectedTime"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Selected Time: "
        android:textSize="18sp"
        android:layout_marginTop="16dp"/>

</LinearLayout>
MainActivity.java
In the MainActivity.java, we'll set up listeners for the Date Picker and Time Picker dialogs. When a user selects a date or time, it will be displayed in the TextView below the respective button.
package com.example.dateandtimepicker;

import android.app.DatePickerDialog;
import android.app.TimePickerDialog;
import android.os.Bundle;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import java.util.Calendar;

public class MainActivity extends AppCompatActivity {

    private Button btnDate, btnTime;
    private TextView tvSelectedDate, tvSelectedTime;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize views
        btnDate = findViewById(R.id.btnDate);
        btnTime = findViewById(R.id.btnTime);
        tvSelectedDate = findViewById(R.id.tvSelectedDate);
        tvSelectedTime = findViewById(R.id.tvSelectedTime);

        // Set onClickListener for the Date Picker button
        btnDate.setOnClickListener(v -> openDatePicker());

        // Set onClickListener for the Time Picker button
        btnTime.setOnClickListener(v -> openTimePicker());
    }

    // Method to open Date Picker
    private void openDatePicker() {
        // Get the current date
        Calendar calendar = Calendar.getInstance();
        int year = calendar.get(Calendar.YEAR);
        int month = calendar.get(Calendar.MONTH);
        int day = calendar.get(Calendar.DAY_OF_MONTH);

        // Create and show the Date Picker Dialog
        DatePickerDialog datePickerDialog = new DatePickerDialog(this, 
                (view, selectedYear, selectedMonth, selectedDay) -> {
                    // Display selected date in the TextView
                    tvSelectedDate.setText("Selected Date: " + selectedDay + "/" + (selectedMonth + 1) + "/" + selectedYear);
                }, year, month, day);
        datePickerDialog.show();
    }

    // Method to open Time Picker
    private void openTimePicker() {
        // Get the current time
        Calendar calendar = Calendar.getInstance();
        int hour = calendar.get(Calendar.HOUR_OF_DAY);
        int minute = calendar.get(Calendar.MINUTE);

        // Create and show the Time Picker Dialog
        TimePickerDialog timePickerDialog = new TimePickerDialog(this, 
                (view, selectedHour, selectedMinute) -> {
                    // Display selected time in the TextView
                    tvSelectedTime.setText("Selected Time: " + selectedHour + ":" + String.format("%02d", selectedMinute));
                }, hour, minute, true);
        timePickerDialog.show();
    }
}
Slips

Code

assets/employee.json

menu_options.xml (for Options Menu)

menu_context.xml (for Context Menu)

menu_popup.xml (for Popup Menu)

XML Layout (activity_main.xml)

Java Code for MainActivity

XML Layout (activity_second.xml) for Second Activity

Java Code for SecondActivity.java

AndroidManifest.xml

activity_main.xml

activity_dashboard.xml

MainActivity.java

DashboardActivity.java

AndroidManifest.xml

activity_main.xml (Main Activity Layout)

activity_result.xml (Result Activity Layout)

MainActivity.java (Main Activity Logic)

ResultActivity.java (Result Activity Logic)

AndroidManifest.xml (Manifest File)

build.gradle (app level)

2. App.js (Main Application File)

3. App.css (Styling the To-Do List)

. Layout File (activity_main.xml)

2. MainActivity.java

3. AndroidManifest.xml

(activity_main.xml)

MainActivity.java

Contact Item Layout (contact_item.xml)

Model Class (Contact.java)

RecyclerView Adapter (ContactAdapter.java)

MainActivity (MainActivity.java)

Layout for MainActivity (activity_main.xml)

Gradle Dependencies (for Glide)

activity_main.xml

MainActivity.java

Comments

Post a Comment

`assets/employee.json`

`menu_options.xml` (for Options Menu)

XML Layout (`activity_main.xml`)

XML Layout (`activity_second.xml`) for Second Activity

`activity_main.xml`

`activity_dashboard.xml`

`MainActivity.java`

`DashboardActivity.java`

`AndroidManifest.xml`

`activity_main.xml` (Main Activity Layout)

`activity_result.xml` (Result Activity Layout)

`MainActivity.java` (Main Activity Logic)

`ResultActivity.java` (Result Activity Logic)

`AndroidManifest.xml` (Manifest File)

`build.gradle` (app level)

(`activity_main.xml`)

Contact Item Layout (`contact_item.xml`)

Model Class (`Contact.java`)

RecyclerView Adapter (`ContactAdapter.java`)

MainActivity (`MainActivity.java`)

Layout for MainActivity (`activity_main.xml`)

`activity_main.xml`
