Define an interface your Service will use to communicate events:
public interface ServiceCallbacks {
void doSomething();
}
Write your Service class. Your Activity will bind to this service, so follow the sample shown here. In addition, we will add a method to set the ServiceCallbacks
.
public class MyService extends Service {
// Binder given to clients
private final IBinder binder = new LocalBinder();
// Registered callbacks
private ServiceCallbacks serviceCallbacks;
// Class used for the client Binder.
public class LocalBinder extends Binder {
MyService getService() {
// Return this instance of MyService so clients can call public methods
return MyService.this;
}
}
@Override
public IBinder onBind(Intent intent) {
return binder;
}
public void setCallbacks(ServiceCallbacks callbacks) {
serviceCallbacks = callbacks;
}
}
Write your Activity class following the same guide, but also make it implement your ServiceCallbacks interface. When you bind/unbind from the Service, you will register/unregister it by calling setCallbacks
on the Service.
public class MyActivity extends Activity implements ServiceCallbacks {
private MyService myService;
private boolean bound = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(...);
}
@Override
protected void onStart() {
super.onStart();
// bind to Service
Intent intent = new Intent(this, MyService.class);
bindService(intent, serviceConnection, Context.BIND_AUTO_CREATE);
}
@Override
protected void onStop() {
super.onStop();
// Unbind from service
if (bound) {
myService.setCallbacks(null); // unregister
unbindService(serviceConnection);
bound = false;
}
}
/** Callbacks for service binding, passed to bindService() */
private ServiceConnection serviceConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName className, IBinder service) {
// cast the IBinder and get MyService instance
LocalBinder binder = (LocalBinder) service;
myService = binder.getService();
bound = true;
myService.setCallbacks(MyActivity.this); // register
}
@Override
public void onServiceDisconnected(ComponentName arg0) {
bound = false;
}
};
/* Defined by ServiceCallbacks interface */
@Override
public void doSomething() {
...
}
}
Now when your service wants to communicate back to the activity, just call one of the interface methods from earlier. Inside your service:
if (serviceCallbacks != null) {
serviceCallbacks.doSomething();
}