Assignment 3

1) Explain broadcast receiver and their types.

Broadcast Receiver in Android

A Broadcast Receiver is a component in Android that listens for system-wide or custom broadcast messages. These messages can be sent by the system (e.g., battery low, network change) or by applications (e.g., custom event notifications).

Types of Broadcast Receivers in Android

System Broadcast Receivers – Receive predefined system broadcasts (e.g., battery low, boot completed).
Custom Broadcast Receivers – Apps send and receive their own broadcasts for internal communication.

1. System Broadcast Receivers

These are sent by Android when certain system events occur.

Event	Intent Action
Battery Low	`Intent.ACTION_BATTERY_LOW`
Boot Completed	`Intent.ACTION_BOOT_COMPLETED`
Airplane Mode Change	`Intent.ACTION_AIRPLANE_MODE_CHANGED`
Wi-Fi State Change	`WifiManager.WIFI_STATE_CHANGED_ACTION`

Example: Listening for Battery Low

1. Create a Broadcast Receiver (`BatteryReceiver.java`)


import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;
 
public class BatteryReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Toast.makeText(context, "Battery is low!", Toast.LENGTH_LONG).show();
    }
}

2. Register the Receiver in `AndroidManifest.xml`


<receiver android:name=".BatteryReceiver">
    <intent-filter>
        <action android:name="android.intent.action.BATTERY_LOW"/>
    </intent-filter>
</receiver>

2. Custom Broadcast Receivers

Apps can send and receive their own broadcasts.

Example: Sending and Receiving a Custom Broadcast

1. Create a Custom Receiver (`MyReceiver.java`)


import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;
 
public class MyReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Toast.makeText(context, "Custom Broadcast Received!", Toast.LENGTH_SHORT).show();
    }
}

2. Register the Receiver in `AndroidManifest.xml`


<receiver android:name=".MyReceiver">
    <intent-filter>
        <action android:name="com.example.CUSTOM_BROADCAST"/>
    </intent-filter>
</receiver>

3. Send a Custom Broadcast from an Activity


Intent intent = new Intent("com.example.CUSTOM_BROADCAST");
sendBroadcast(intent);

Types of Broadcasts Based on Execution

Type	Description
Ordered Broadcast	Delivered one receiver at a time, allowing modification before passing to the next receiver.
Normal Broadcast	Delivered to all receivers at once, without modification.
Sticky Broadcast (Deprecated)	Persists even after broadcast is received, useful for system updates.
Local Broadcast (Replaced by LiveData or EventBus)	Broadcasts within an app only for efficiency.

Use Cases of Broadcast Receivers

✔ Battery & Network Status Updates
✔ Push Notifications
✔ Alarm & Reminders
✔ Custom Event Handling Between Components

Conclusion

Broadcast Receivers allow apps to listen for system and custom events, improving communication between components. They can be statically registered in the manifest or dynamically registered in Java for better control.

2) Explain services with their types.

Services in Android

A Service in Android is a background component that performs long-running operations without needing a user interface (UI). It allows tasks like playing music, fetching data, or handling network requests to run in the background.

Types of Services in Android

Android provides three main types of services based on how they operate:

Foreground Service – Runs in the background with a visible notification.
Background Service – Runs in the background without user interaction.
Bound Service – Allows components (Activities, Fragments, etc.) to bind and interact with it.

Diagram: Service Lifecycle in Android


              ┌───────────────────┐
              |    onCreate()      | → Service is created
              └───────────────────┘
                      ↓
              ┌───────────────────┐
              | onStartCommand()   | → Service starts running
              └───────────────────┘
                      ↓
        ┌──────────────────────────┐
        | Service is Running       |
        | (Foreground/Background)  |
        └──────────────────────────┘
                      ↓
              ┌───────────────────┐
              |    onDestroy()     | → Service stops
              └───────────────────┘

1. Foreground Service

✔ Runs in the background but remains visible via a persistent notification.
✔ Used for music players, tracking apps, or ongoing processes.
✔ Requires startForeground() method.

Example: Foreground Service with Notification


import android.app.Notification;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.Service;
import android.content.Intent;
import android.os.Build;
import android.os.IBinder;
import androidx.core.app.NotificationCompat;
 
public class MyForegroundService extends Service {
    private static final String CHANNEL_ID = "ForegroundServiceChannel";
 
    @Override
    public void onCreate() {
        super.onCreate();
        createNotificationChannel();
        Notification notification = new NotificationCompat.Builder(this, CHANNEL_ID)
                .setContentTitle("Foreground Service")
                .setContentText("Running in the background")
                .setSmallIcon(R.drawable.ic_launcher_foreground)
                .build();
        startForeground(1, notification);
    }
 
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        return START_STICKY;
    }
 
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
 
    private void createNotificationChannel() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            NotificationChannel channel = new NotificationChannel(
                    CHANNEL_ID, "Foreground Service", NotificationManager.IMPORTANCE_LOW);
            NotificationManager manager = getSystemService(NotificationManager.class);
            manager.createNotificationChannel(channel);
        }
    }
}

✅ Use Cases: Music players, GPS tracking, file downloads.

2. Background Service

✔ Runs in the background without user interaction.
✔ Used for short-term tasks like syncing data, sending notifications.
✔ Can be stopped by the system if low on memory.

Example: Background Service


import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.widget.Toast;
 
public class MyBackgroundService extends Service {
    @Override
    public void onCreate() {
        super.onCreate();
        Toast.makeText(this, "Background Service Started", Toast.LENGTH_SHORT).show();
    }
 
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        new Thread(() -> {
            // Perform background task here
        }).start();
        return START_STICKY;
    }
 
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}

✅ Use Cases: Syncing data, handling notifications, background computations.

3. Bound Service

✔ Runs only while components are bound to it.
✔ Allows Activities, Fragments, or other components to interact with it.
✔ Uses onBind() method to return an IBinder for communication.

Example: Bound Service


import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;
 
public class MyBoundService extends Service {
    private final IBinder binder = new LocalBinder();
 
    public class LocalBinder extends Binder {
        public MyBoundService getService() {
            return MyBoundService.this;
        }
    }
 
    @Override
    public IBinder onBind(Intent intent) {
        return binder;
    }
 
    public String getMessage() {
        return "Hello from Bound Service!";
    }
}

Binding the Service in an Activity


MyBoundService myService;
boolean isBound = false;
 
private ServiceConnection connection = new ServiceConnection() {
    @Override
    public void onServiceConnected(ComponentName name, IBinder service) {
        MyBoundService.LocalBinder binder = (MyBoundService.LocalBinder) service;
        myService = binder.getService();
        isBound = true;
    }
 
    @Override
    public void onServiceDisconnected(ComponentName name) {
        isBound = false;
    }
};
 
// Bind the service
Intent intent = new Intent(this, MyBoundService.class);
bindService(intent, connection, Context.BIND_AUTO_CREATE);

✅ Use Cases: Streaming apps, live data fetching, inter-process communication.

Comparison of Android Services

Feature	Foreground Service	Background Service	Bound Service
Runs in Background	✅ Yes	✅ Yes	✅ Yes
User Interaction Needed?	❌ No	❌ No	✅ Yes
Requires Notification?	✅ Yes	❌ No	❌ No
Can Be Stopped by System?	❌ No	✅ Yes	✅ Yes (if all clients unbind)
Example Use Cases	Music Player, GPS Tracking	Data Syncing, File Uploading	Live Chat, Streaming

Conclusion

✔ Foreground Service – Runs continuously with a notification (e.g., music player, tracking).
✔ Background Service – Runs in the background without UI, suitable for short tasks (e.g., syncing, notifications).
✔ Bound Service – Allows components to bind to it and interact (e.g., fetching live data).

Each service type is essential for different app functionalities, ensuring efficient background processing.

3) Explain alarm manager with the example of broadcast receiver.

AlarmManager in Android with BroadcastReceiver Example

AlarmManager is a system service in Android that schedules tasks to run at a specified time, even if the app is closed or the device is restarted. It is commonly used for reminders, notifications, and periodic background tasks.

Steps to Implement AlarmManager with BroadcastReceiver

To trigger an alarm event at a specific time, we use:

AlarmManager – Schedules the alarm.
PendingIntent – Specifies the action (e.g., sending a broadcast).
BroadcastReceiver – Receives the alarm trigger and performs an action (e.g., showing a notification).

1. Set an Alarm Using AlarmManager (`MainActivity.java`)


import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.widget.Button;
import androidx.appcompat.app.AppCompatActivity;
import java.util.Calendar;
 
public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        Button setAlarmButton = findViewById(R.id.setAlarmButton);
        setAlarmButton.setOnClickListener(v -> setAlarm());
    }
 
    private void setAlarm() {
        // Get AlarmManager instance
        AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
 
        // Intent to trigger the BroadcastReceiver
        Intent intent = new Intent(this, AlarmReceiver.class);
        PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
 
        // Set the alarm time (5 seconds from now)
        Calendar calendar = Calendar.getInstance();
        calendar.add(Calendar.SECOND, 5);
 
        // Schedule an exact alarm
        alarmManager.setExact(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), pendingIntent);
    }
}

2. Create a Broadcast Receiver (`AlarmReceiver.java`)


import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;
 
public class AlarmReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Toast.makeText(context, "Alarm Triggered!", Toast.LENGTH_LONG).show();
    }
}

3. Register the Receiver in `AndroidManifest.xml`


<receiver android:name=".AlarmReceiver"/>

4. Running the App

Click the “Set Alarm” button.
After 5 seconds, the AlarmReceiver receives the broadcast and shows a Toast message.

Using AlarmManager for Repeating Alarms

To repeat the alarm every 10 minutes, modify setExact() to setRepeating():


alarmManager.setRepeating(
    AlarmManager.RTC_WAKEUP,
    calendar.getTimeInMillis(),
    AlarmManager.INTERVAL_FIFTEEN_MINUTES / 1.5, // 10 minutes
    pendingIntent
);

Canceling an Alarm

To cancel an alarm:


alarmManager.cancel(pendingIntent);

Use Cases of AlarmManager with BroadcastReceiver

✔ Reminders and Notifications (e.g., medication alerts).
✔ Periodic Background Tasks (e.g., syncing data, checking updates).
✔ Task Scheduling (e.g., alarms, scheduled reports).

Conclusion

AlarmManager is a powerful tool for scheduling background tasks. When combined with a BroadcastReceiver, it allows apps to perform timed operations even when the app is closed, making it useful for reminders, notifications, and periodic updates.

4) Explain internal storage in Android with example.

Internal Storage in Android

Internal Storage in Android is a private storage space allocated for an app, where files are stored within the device’s internal memory. Data saved here is only accessible to the app itself and is deleted when the app is uninstalled.

Features of Internal Storage

✔ Private Storage – Other apps cannot access the stored files.
✔ Automatically Deleted – Files are removed when the app is uninstalled.
✔ No Permissions Required – Unlike external storage, no special permission is needed.
✔ Secure and Fast – Stored files are sandboxed and cannot be accessed by other apps.

Example: Writing and Reading a File in Internal Storage

1. Write Data to Internal Storage (`MainActivity.java`)


import android.content.Context;
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;
import java.io.FileOutputStream;
import java.io.IOException;
 
public class MainActivity extends AppCompatActivity {
    private static final String FILE_NAME = "myfile.txt";
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        EditText editText = findViewById(R.id.editText);
        Button saveButton = findViewById(R.id.saveButton);
 
        saveButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String text = editText.getText().toString();
                try (FileOutputStream fos = openFileOutput(FILE_NAME, Context.MODE_PRIVATE)) {
                    fos.write(text.getBytes());
                    Toast.makeText(MainActivity.this, "File Saved!", Toast.LENGTH_SHORT).show();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });
    }
}

2. Read Data from Internal Storage (`MainActivity.java`)


import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import java.io.FileInputStream;
import java.io.IOException;
 
public class MainActivity extends AppCompatActivity {
    private static final String FILE_NAME = "myfile.txt";
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        TextView textView = findViewById(R.id.textView);
        Button loadButton = findViewById(R.id.loadButton);
 
        loadButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                try (FileInputStream fis = openFileInput(FILE_NAME)) {
                    int size;
                    StringBuilder stringBuilder = new StringBuilder();
                    while ((size = fis.read()) != -1) {
                        stringBuilder.append((char) size);
                    }
                    textView.setText(stringBuilder.toString());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });
    }
}

File Storage Location in Internal Storage

Files are stored in:
📂 /data/data/com.example.myapp/files/myfile.txt
(Apps cannot access each other’s storage due to Android’s sandboxing.)

Deleting a File from Internal Storage


boolean deleted = deleteFile("myfile.txt");
if (deleted) {
    Toast.makeText(this, "File Deleted!", Toast.LENGTH_SHORT).show();
}

Use Cases of Internal Storage

✔ Saving User Preferences (e.g., settings, user profile data).
✔ Storing Application Data (e.g., cache files, logs).
✔ Keeping Private Files (e.g., authentication tokens).

Comparison: Internal Storage vs. External Storage

Feature	Internal Storage	External Storage
Access Level	Private to the app	Accessible by other apps
Permission Required?	No	Yes (`WRITE_EXTERNAL_STORAGE`)
Data Deletion	Deleted when the app is uninstalled	Persists even after uninstalling
Security	High (sandboxed)	Lower (other apps can access)

Conclusion

Internal Storage in Android provides a secure and private way to store app-specific files. It is useful for storing personal user data, settings, and cache files. Unlike external storage, it does not require permissions and is automatically deleted when the app is uninstalled.

5) Explain SQLite Database with example.

SQLite Database in Android

SQLite is a lightweight, embedded relational database used in Android for storing structured data locally. It does not require a separate server and provides efficient storage for offline applications.

Features of SQLite in Android

✔ Lightweight & Embedded – No external setup needed.
✔ Uses SQL Queries – Supports CRUD operations (Create, Read, Update, Delete).
✔ Local Storage – Stores data in a single file on the device.
✔ Efficient & Fast – Ideal for small to medium-sized applications.

Steps to Implement SQLite Database in Android

1. Create a Database Helper Class (`DatabaseHelper.java`)


import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
 
public class DatabaseHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "students.db";
    private static final int DATABASE_VERSION = 1;
 
    private static final String CREATE_TABLE =
            "CREATE TABLE students (id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, age INTEGER)";
 
    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }
 
    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_TABLE); // Create students table
    }
 
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS students");
        onCreate(db);
    }
}

2. Insert Data into SQLite (`MainActivity.java`)


import android.content.ContentValues;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
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);
 
        DatabaseHelper dbHelper = new DatabaseHelper(this);
        SQLiteDatabase db = dbHelper.getWritableDatabase();
 
        ContentValues values = new ContentValues();
        values.put("name", "John Doe");
        values.put("age", 25);
 
        long result = db.insert("students", null, values);
        db.close();
 
        if (result != -1) {
            Toast.makeText(this, "Data Inserted Successfully!", Toast.LENGTH_SHORT).show();
        }
    }
}

3. Retrieve Data from SQLite (`MainActivity.java`)


import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
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);
 
        DatabaseHelper dbHelper = new DatabaseHelper(this);
        SQLiteDatabase db = dbHelper.getReadableDatabase();
 
        Cursor cursor = db.rawQuery("SELECT * FROM students", null);
 
        if (cursor.moveToFirst()) {
            do {
                String name = cursor.getString(cursor.getColumnIndex("name"));
                int age = cursor.getInt(cursor.getColumnIndex("age"));
 
                Toast.makeText(this, "Name: " + name + ", Age: " + age, Toast.LENGTH_SHORT).show();
            } while (cursor.moveToNext());
        }
 
        cursor.close();
        db.close();
    }
}

4. Update Data in SQLite (`MainActivity.java`)


SQLiteDatabase db = new DatabaseHelper(this).getWritableDatabase();
ContentValues values = new ContentValues();
values.put("age", 30);
 
int rowsAffected = db.update("students", values, "name=?", new String[]{"John Doe"});
db.close();
 
if (rowsAffected > 0) {
    Toast.makeText(this, "Data Updated Successfully!", Toast.LENGTH_SHORT).show();
}

5. Delete Data from SQLite (`MainActivity.java`)


SQLiteDatabase db = new DatabaseHelper(this).getWritableDatabase();
int rowsDeleted = db.delete("students", "name=?", new String[]{"John Doe"});
db.close();
 
if (rowsDeleted > 0) {
    Toast.makeText(this, "Data Deleted Successfully!", Toast.LENGTH_SHORT).show();
}

Use Cases of SQLite

✔ Offline Applications – Stores data locally without internet.
✔ User Data Storage – Saves preferences, settings, and history.
✔ Small to Medium Databases – Efficient for mobile apps.

Conclusion

SQLite in Android provides a powerful, local database for storing structured data. It supports CRUD operations and is widely used for offline applications, user data storage, and local caching.

Assignment 3

1) Explain broadcast receiver and their types.

Broadcast Receiver in Android

Types of Broadcast Receivers in Android

1. System Broadcast Receivers

Example: Listening for Battery Low

1. Create a Broadcast Receiver (BatteryReceiver.java)

2. Register the Receiver in AndroidManifest.xml

2. Custom Broadcast Receivers

Example: Sending and Receiving a Custom Broadcast

1. Create a Custom Receiver (MyReceiver.java)

2. Register the Receiver in AndroidManifest.xml

3. Send a Custom Broadcast from an Activity

Types of Broadcasts Based on Execution

Use Cases of Broadcast Receivers

Conclusion

2) Explain services with their types.

Services in Android

Types of Services in Android

Diagram: Service Lifecycle in Android

1. Foreground Service

Example: Foreground Service with Notification

2. Background Service

Example: Background Service

3. Bound Service

Example: Bound Service

Binding the Service in an Activity

Comparison of Android Services

Conclusion

3) Explain alarm manager with the example of broadcast receiver.

AlarmManager in Android with BroadcastReceiver Example

Steps to Implement AlarmManager with BroadcastReceiver

1. Set an Alarm Using AlarmManager (MainActivity.java)

2. Create a Broadcast Receiver (AlarmReceiver.java)

3. Register the Receiver in AndroidManifest.xml

4. Running the App

Using AlarmManager for Repeating Alarms

Canceling an Alarm

Use Cases of AlarmManager with BroadcastReceiver

Conclusion

4) Explain internal storage in Android with example.

Internal Storage in Android

Features of Internal Storage

Example: Writing and Reading a File in Internal Storage

1. Write Data to Internal Storage (MainActivity.java)

2. Read Data from Internal Storage (MainActivity.java)

File Storage Location in Internal Storage

Deleting a File from Internal Storage

Use Cases of Internal Storage

Comparison: Internal Storage vs. External Storage

Conclusion

5) Explain SQLite Database with example.

SQLite Database in Android

Features of SQLite in Android

Steps to Implement SQLite Database in Android

1. Create a Database Helper Class (DatabaseHelper.java)

2. Insert Data into SQLite (MainActivity.java)

3. Retrieve Data from SQLite (MainActivity.java)

4. Update Data in SQLite (MainActivity.java)

5. Delete Data from SQLite (MainActivity.java)

Use Cases of SQLite

Conclusion

1. Create a Broadcast Receiver (`BatteryReceiver.java`)

2. Register the Receiver in `AndroidManifest.xml`

1. Create a Custom Receiver (`MyReceiver.java`)

2. Register the Receiver in `AndroidManifest.xml`

1. Set an Alarm Using AlarmManager (`MainActivity.java`)

2. Create a Broadcast Receiver (`AlarmReceiver.java`)

3. Register the Receiver in `AndroidManifest.xml`

1. Write Data to Internal Storage (`MainActivity.java`)

2. Read Data from Internal Storage (`MainActivity.java`)

1. Create a Database Helper Class (`DatabaseHelper.java`)

2. Insert Data into SQLite (`MainActivity.java`)

3. Retrieve Data from SQLite (`MainActivity.java`)

4. Update Data in SQLite (`MainActivity.java`)

5. Delete Data from SQLite (`MainActivity.java`)