Question

In my Android application, I have a simple list view with adapter. There’s a heavy query which is to fill the list view with data. So I put it to an IntentService that runs in another thread.

The IntentService is normally running separately, on its own, just to query some data and insert it into the SQLite database.

But now I would like to have the following possibility:

1. The activity starts the IntentService with startService().
2. The IntentService does its heavy work.
3. When the IntentService is finished, it should inform the activity about the result so that the activity can be refreshed to show the new data.

Is this possible? I read a lot of questions here on Stack Overflow on this topic. But in every question, there was another solution. So I want to ask you all: Which solution is the best for my purpose?

• Binding the IntentService to the Activity does not seem to be the best solution as there might be conflicts with configuration changes of the activity etc. Correct?
• This blog post suggests using AIDL with Parcelables – which sounds very complex to me. There is an easier way, isn’t it?
• One could set up a broadcast receiver in the activity and fire this broadcast in the IntentService when it is finished.
• Some people say you should use createPendingResult() to pass a PendingIntent to the IntentService. If the IntentService finds that PendingIntent in its extras, it uses this to trigger off onActivityResult() in the Activity. Is this the way to choose?

Answer 1

As an example, I use a ResultReceiver to call notifyDataSetChanged() on the adapter of my Activity (which extends ListActivity). It can be adapted to do whatever you need.

ResultReceiver code:

public class MyResultReceiver extends ResultReceiver {

    private Context context = null;

    protected void setParentContext (Context context) {
        this.context = context;
    }

    public MyResultReceiver(Handler handler) {
        super(handler);
    }

    @Override
    protected void onReceiveResult (int resultCode, Bundle resultData) {

        // Code to process resultData here

        ((BaseAdapter) ((ListActivity)context).getListAdapter()).notifyDataSetChanged();
    }
}

MyActivity code:

public class MyActivity extends ListActivity {

    private MyResultReceiver theReceiver = null;

    ...

    private void callService () {
        theReceiver = new MyResultReceiver(new Handler());
        theReceiver.setParentContext(this);
        Intent i = new Intent("com.mycompany.ACTION_DO_SOMETHING");

        // Code to define and initialize myData here

        i.putExtra("someData", myData);
        i.putExtra("resReceiver", theReceiver);
        startService(i);

    }
}

IntentService code:

Bundle resultBundle = new Bundle();
ResultReceiver resRec = intent.getParcelableExtra("resReceiver");

// Do some work then put some stuff in resultBundle here

resRec.send(12345, resultBundle);