/////////////////////
/////// timer ///////
/////////////////////
private void runTimer() {

    myTimer = new Timer();
    myTimer.schedule(new TimerTask() {
        @Override
        public void run() {
            TimerMethod();
        }

    }, 5000, 5000);
}

private Runnable Timer_Tick = new Runnable() {
    public void run() {

        // next image if THIS one is loaded
        nextImage();
    }
};

private void TimerMethod() {
    getActivity().runOnUiThread(Timer_Tick);
}