private Handler handler = new Handler(); // created on the main thread

private void executeOnSeparateThread() {
  Thread separateThread = new Thread(new Runnable() {
    @Override
    public void run() {
      // do some background processing here
      handler.post(new Runnable() {
        @Override
        public void run() {
          // access the graphical user interface here
        }
      });
    }
  });
  separateThread.start();
}