Executing Asynchronous Task From Service In Android

I was developping an application and I ran into a problem. I was trying to run an asynchronous task from a service and it didn't work. It says that the code is unreachable. Now I k

Solution 1:

AsyncTask always works on main/UI thread. And if your Service is running under a different process then it is not associated to main thread, that's why you cant use AsyncTask in Service.

In your case, you are encouraged to use HandlerThread, Looper and Handler to perform heavy lifting on separate thread.

Read this article.

Solution 2:

you can use HandlerThread in your service for doing background work like:

publicclassServicewithHandlerThreadextendsService {
  private Looper mServiceLooper;
  private ServiceHandler mServiceHandler;
  privatefinalclassServiceHandlerextendsHandler {
      publicServiceHandler(Looper looper) {
          super(looper);
      }
      @OverridepublicvoidhandleMessage(Message msg) {

          while (true) {
              synchronized (this) {
                  try {
                      //YOUR BACKGROUND WORK HERE
                  } catch (Exception e) {
                  }
              }
          }
          stopSelf(msg.arg1);
      }
  }
  @OverridepublicvoidonCreate() {
    // Start up the thread running the service.HandlerThreadthread=newHandlerThread("ServiceStartArguments",
            Process.THREAD_PRIORITY_BACKGROUND);
    thread.start();
    // Get the HandlerThread's Looper and use it for our Handler
    mServiceLooper = thread.getLooper();
    mServiceHandler = newServiceHandler(mServiceLooper);
  }

  @OverridepublicintonStartCommand(Intent intent, int flags, int startId) {
      Messagemsg= mServiceHandler.obtainMessage();
      msg.arg1 = startId;
      mServiceHandler.sendMessage(msg);
      return START_STICKY;
  }
  @Overridepublic IBinder onBind(Intent intent) {
      returnnull;
  }
}

Solution 3:

There's a few options. If you need communication between your task and say, an activity, AsyncTask would be your best best, IMO. If you just need to "fire and forget", IntentService can be of help.

Remember, a service still runs on the main thread. If you need to do anything that requires some processing or lookup such as network download/upload or SQL queries, you should move that to a new thread using on of the aforementioned classes.