Show loading icon in the activity titlebar

@Override
public void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
    setContentView(R.layout.your_layout);
}

Then... where ever you want:

// then, you can do this to show the icon
setProgressBarIndeterminateVisibility(true);
//or to hide it
setProgressBarIndeterminateVisibility(false);

Make sure to use requestWindowFeature before setContentView.