mediaPlayer.start();
    CountDownTimer timer = new CountDownTimer(5000, 1000) {

        @Override
        public void onTick(long millisUntilFinished) {
            // Nothing to do
        }

        @Override
        public void onFinish() {
            if ( mediaPlayer.isPlaying()) {
                mediaPlayer.stop();

            }

        }
    };
    timer.start();