Services in Android

What is a Service in Android?

A Service in Android is a component that runs in the background without a user interface. It is useful for long-running tasks such as:
✅ Playing music
✅ Downloading files
✅ Fetching data from the internet
✅ Running a background task (e.g., location tracking)

Types of Services in Android

Service Type Description Example
Started Service Runs in the background until stopped manually Music Player, File Download
Bound Service Allows communication between an Activity and the Service Fetching Data from API
Foreground Service Runs with higher priority and shows a notification GPS Tracking, Music Player

Example: Creating a Service in Android

We will create an app where:
✅ A Service runs in the background
✅ The Activity binds to the Service and retrieves data
✅ The Service runs in a separate thread

Add Service in AndroidManifest.xml 

<service android:name=".MyService" />

Create a Service (MyService.java)

public class MyService extends Service {

    private final IBinder binder = new MyBinder();
    private int counter = 0;
    private boolean isRunning = true;


    public class MyBinder extends Binder {
        public MyService getService() {
            return MyService.this;
        }
    }

    public IBinder onBind(Intent intent) {
        return binder;
    }

    public int onStartCommand(Intent intent, int flags, int startId) {
        new Thread(() -> {
            while (isRunning) {
                counter++;
                Log.d("MyService", "Counter: " + counter);
                try {
                    Thread.sleep(1000); // Sleep for 1 second
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }).start();
        return START_STICKY;
    }

    public int getCounter() {
        return counter;
    }

    public void onDestroy() {
        super.onDestroy();  //  Ensure you call the superclass method
        isRunning = false;
        Log.d("MyService", "Service is stopped.");
    }
}

✅ This Service runs in the background
✅ It increments a counter every second
✅ It runs in a separate thread using new Thread(() -> {...}).start();

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="20dp">

    <Button
        android:id="@+id/btnStart"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Start Service" />

    <Button
        android:id="@+id/btnBind"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Bind to Service" />

    <TextView
        android:id="@+id/textViewCounter"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="20sp"
        android:paddingTop="20dp"/>
</LinearLayout>

✅ Button 1 → Starts the Service
✅ Button 2 → Binds to the Service and gets the counter value
✅ TextView → Displays the counter value

Java Code (MainActivity.java)

public class MainActivity extends AppCompatActivity {

    private MyService myService;
    private boolean isBound = false;

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

        Button btnStart = findViewById(R.id.btnStart);
        Button btnBind = findViewById(R.id.btnBind);
        TextView textViewCounter = findViewById(R.id.textViewCounter);

        btnStart.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(MainActivity.this, MyService.class);
                startService(intent);
            }
        });

        btnBind.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (isBound) {
                    int count = myService.getCounter();
                    textViewCounter.setText("Counter: " + count);
                }
            }
        });
    }

    // Service connection to bind the activity with the service
    private ServiceConnection serviceConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            MyService.MyBinder binder = (MyService.MyBinder) service;
            myService = binder.getService();
            isBound = true;
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            isBound = false;
        }
    };

    @Override
    protected void onStart() {
        super.onStart();
        Intent intent = new Intent(this, MyService.class);
        bindService(intent, serviceConnection, BIND_AUTO_CREATE);
    }

    @Override
    protected void onStop() {
        super.onStop();
        if (isBound) {
            unbindService(serviceConnection);
            isBound = false;
        }
    }
}

✅ Click “Start Service” → Starts the service in the background
✅ Click “Bind to Service” → Fetches the counter value from the service