Android: Expandable list group icon

drawable/groupindicator_icon

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_expanded="true" android:drawable="@drawable/arrow_up" />
    <item android:drawable="@drawable/arrow_down" />
</selector>

The images have to be 9 patch images, like the following:

Align icon to the right

@Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        DisplayMetrics metrics = new DisplayMetrics();
        getActivity().getWindowManager().getDefaultDisplay().getMetrics(metrics);
        int width = metrics.widthPixels;
        if(android.os.Build.VERSION.SDK_INT < android.os.Build.VERSION_CODES.JELLY_BEAN_MR2) {
            listView.setIndicatorBounds(width-getPixelFromDips(HORIZONTAL_PADDING*2)-getPixelFromDips(35), width-getPixelFromDips(HORIZONTAL_PADDING*2-getPixelFromDips(5)));
        } else {
            listView.setIndicatorBoundsRelative(width-getPixelFromDips(HORIZONTAL_PADDING*2)-getPixelFromDips(35), width-getPixelFromDips(HORIZONTAL_PADDING*2)-getPixelFromDips(5));
        }
    }

    public int getPixelFromDips(float pixels) {
        final float scale = getResources().getDisplayMetrics().density;
        return (int) (pixels * scale + 0.5f);
    }

Note: If you get a "No resource found..." even when the 9 patch is there it is because the 9 patch is not properly created.