Run Callback On Main Thread

runOnUiThread(new Runnable() {
    @Override
    public void run() {
        //execute code on main thread
    }
});

As long as you have a Context, you can do something like this:

Handler mainHandler = new Handler(context.getMainLooper());

And to run code on UI thread:

mainHandler.post(new Runnable() {

    @Override
    public void run() {
        // run code
    }
});

As suggested by kaka:

You could also use the static Looper.getMainLooper() which

Returns the application's main looper, which lives in the main thread of the application.