Beginner android help playing audio from within a runnable

Question

I'm playing around with some basic android, and I'm trying to write a metronome app. The basic idea is that I'm using a runnable in order to trigger a sound after a time period (msPeriod). I've tried to use SoundPool, but it will just log 'sample not loaded', and trying to ititialise a MediaPlayer causes the app to crash on opening. Could you explain to me where I'm going wrong please? Below is my code with MediaPlayer.

//I create the media player first thing inside MainActivity
private Handler handler = new Handler();
int msPeriod = 1000;
MediaPlayer mpHigh = MediaPlayer.create(this, R.raw.hightick);
MediaPlayer mpLow = MediaPlayer.create(this, R.raw.lowtick);

//within an onClick Listener 
onClick(View v) { handler.postDelayed(startMetron, msPeriod); }

//the runnable that starts the metronome
private Runnable startMetron = new Runnable( ) {

    @Override
    public void run() {

        if(isRunning){
            if (count == 4) {
                count = 1;
                mphigh.start();

            } else {
                count++;
                mplow.start();
            }
        }

        textCount.setText(String.valueOf(count));

        //triggering the next run
        handler.postDelayed(this, msPeriod);
    }
};

Thanks so much for bearing with me!

Answer 1

You are running a separate thread . The UI element must be updated form the main thread... so..

runOnUiThread(new Runnable(){
        public void run() {
            textCount.setText(String.valueOf(count));
        }
    });

This makes sure that the textview is update from the UI thread and your app will not crash.