Creating an unbound service

The first thing to do is to add the service to AndroidManifest.xml, inside the <application> tag:

<application ...>

    ...        

    <service
        android:name=".RecordingService"
        <!--"enabled" tag specifies Whether or not the service can be instantiated by the system — "true" -->
        <!--if it can be, and "false" if not. The default value is "true".-->
        android:enabled="true"
        <!--exported tag specifies Whether or not components of other applications can invoke the -->
        <!--service or interact with it — "true" if they can, and "false" if not. When the value-->
        <!--is "false", only components of the same application or applications with the same user -->
        <!--ID can start the service or bind to it.-->
        android:exported="false" />

</application>

If your intend to manage your service class in a separate package (eg: .AllServices.RecordingService) then you will need to specify where your service is located. So, in above case we will modify:

android:name=".RecordingService"

android:name=".AllServices.RecordingService"

or the easiest way of doing so is to specify the full package name.

Then we create the actual service class:

public class RecordingService extends Service {
    private int NOTIFICATION = 1; // Unique identifier for our notification

    public static boolean isRunning = false;
    public static RecordingService instance = null;

private NotificationManager notificationManager = null;

@Override
public IBinder onBind(Intent intent) {
    return null;
}

@Override
public void onCreate(){
    instance = this;
    isRunning = true;

    notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);

    super.onCreate();
}

@Override
public int onStartCommand(Intent intent, int flags, int startId){
    // The PendingIntent to launch our activity if the user selects this notification
    PendingIntent contentIntent = PendingIntent.getActivity(this, 0, new Intent(this, MainActivity.class), 0);

    // Set the info for the views that show in the notification panel.
    Notification notification = new NotificationCompat.Builder(this)
            .setSmallIcon(R.mipmap.ic_launcher)        // the status icon
            .setTicker("Service running...")           // the status text
            .setWhen(System.currentTimeMillis())       // the time stamp
            .setContentTitle("My App")                 // the label of the entry
            .setContentText("Service running...")      // the content of the entry
            .setContentIntent(contentIntent)           // the intent to send when the entry is clicked
            .setOngoing(true)                          // make persistent (disable swipe-away)
            .build();

    // Start service in foreground mode
    startForeground(NOTIFICATION, notification);

    return START_STICKY;
}

@Override
public void onDestroy(){
    isRunning = false;
    instance = null;

    notificationManager.cancel(NOTIFICATION); // Remove notification

    super.onDestroy();
}

public void doSomething(){
    Toast.makeText(getApplicationContext(), "Doing stuff from service...", Toast.LENGTH_SHORT).show();
}

}

All this service does is show a notification when it’s running, and it can display toasts when its doSomething() method is called.

As you’ll notice, it’s implemented as a singleton, keeping track of its own instance - but without the usual static singleton factory method because services are naturally singletons and are created by intents. The instance is useful to the outside to get a “handle” to the service when it’s running.

Last, we need to start and stop the service from an activity:

public void startOrStopService(){
    if( RecordingService.isRunning ){
        // Stop service
        Intent intent = new Intent(this, RecordingService.class);
        stopService(intent);
    }
    else {
        // Start service
        Intent intent = new Intent(this, RecordingService.class);
        startService(intent);
    }
}

In this example, the service is started and stopped by the same method, depending on it’s current state.

We can also invoke the doSomething() method from our activity:

public void makeServiceDoSomething(){
    if( RecordingService.isRunning )
        RecordingService.instance.doSomething();
}

Found a mistake? Have a question or improvement idea? Let me know.

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