Services

A Service is an Android component that performs long-running operations in the background or exposes functionality to other components, without a user interface.

Use a Service when:
- Work must continue even if the app is not visible
- Multiple components need to access the same background logic
- The operation doesn’t belong to UI lifecycle

Service Lifecycle

onCreate()
- Called once
- Initialize resources
- Equivalent to setup phase
onStartCommand(Intent, flags, startId)
- Called when startService() is invoked
- This is where work usually begins
- Can be called multiple times
onBind(Intent)
- Used for bound services
- Returns an IBinder
- If unused, return null
onDestroy()
- Cleanup

Types of Services

1. Started Service

Started using:

startService(intent);

Characteristics:
- Runs indefinitely until stopped
- Independent of the component that started it
- Must stop itself or be stopped explicitly

Stopping:

stopSelf();
stopService(intent);

Typical use:
- File download
- Syncing data
- Logging
- Uploading analytics

2. Bound Service

Started using:

bindService(intent, connection, BIND_AUTO_CREATE);

Characteristics:
- Client-server model
- Exists only while at least one client is bound
- Exposes methods via IBinder
Typical use:
- Music playback control
- Shared computation
- Data providers within app

Multiple components can bind to the service at once, but when all of them unbind, the service is destroyed.

3. Started + Bound Service

Started → controls lifetime
Bound → controls communication
Service dies only when:
- stopSelf() is called and
- all clients are unbound

Execution Modes of Services

Foreground Service:

A foreground service performs some operation that is noticeable to the user.

Foreground services must display a Notification.

Foreground services continue running even when the user isn't interacting with the app. (It stays alive even when the app is closed).

Example:
- Music
- Navigation
- Ongoing call
- Fitness tracking

Background Service:

A service running without foreground notification.

A background service performs an operation that isn't directly noticed by the user.

It runs only when the app is running, (It is terminated when the app is terminated).

Intent Service

Automatically runs on a single background thread
Processes intents sequentially (queue, since it's a single thread)
Stops itself when done

Why deprecated:

Poor flexibility
Replaced by better tools

MainActivity.java

Intent intent = new Intent(MainActivity.this, MyIntentService.class);
startService(intent);

MyIntentService.java

public class MyIntentService extends IntentService {
    private static final String TAG = "MyIntentService";
    public static final String name = "IntentWorker";
    public MyIntentService() {
        super(name);
    }

    @Override
    protected void onHandleIntent(@Nullable Intent intent) {
        Log.d(TAG, "For intent : " + intent.getAction());

        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        Log.d(TAG, "Task Completed");
    }
}

Last modified: 05 February 2026