Sleep function in android program

Question

Having some problem getting my program to sleep What im trying to do is when the btnStart is pressed firs randomly set pictures to 12 ImageButtons Then i want it to pause for 5 secs and then change the first ImageButton to another picture

My code looks like this, right now it pauses straight away when the button is pressed...

       btnStart.setOnClickListener(new View.OnClickListener() {
        @Override

        public void onClick(View v) {
            // TODO Auto-generated method stub

            Collections.shuffle(pic);
            int time=1;
            press=true;

            pic.get(0).setImageDrawable(getResources().getDrawable(R.drawable.memgreen));
            pic.get(1).setImageDrawable(getResources().getDrawable(R.drawable.memgreen));
            pic.get(2).setImageDrawable(getResources().getDrawable(R.drawable.memred));
            pic.get(3).setImageDrawable(getResources().getDrawable(R.drawable.memred));
            pic.get(4).setImageDrawable(getResources().getDrawable(R.drawable.memblue));
            pic.get(5).setImageDrawable(getResources().getDrawable(R.drawable.memblue));
            pic.get(6).setImageDrawable(getResources().getDrawable(R.drawable.memwhite));
            pic.get(7).setImageDrawable(getResources().getDrawable(R.drawable.memwhite));
            pic.get(8).setImageDrawable(getResources().getDrawable(R.drawable.mempurple));
            pic.get(9).setImageDrawable(getResources().getDrawable(R.drawable.mempurple));
            pic.get(10).setImageDrawable(getResources().getDrawable(R.drawable.memyellow));
            pic.get(11).setImageDrawable(getResources().getDrawable(R.drawable.memyellow));

            try {
                Thread.sleep(5000);

                pic.get(0).setImageDrawable(getResources().getDrawable(R.drawable.coin));

            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
     }
  });

Answer 1

Well, if you want the UI to remain responsive you can't block the UI thread with Thread.sleep there.

Create a new thread, then sleep it. After the sleep, run the method for changing the view drawable on the UI thread

new Thread(new Runnable() {
    @Override
    public void run() {
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                pic.get(0).setImageDrawable(getResources().getDrawable(R.drawable.coin));
            }
        });
    }
}).start();

Answer 2

Create an image array and set a handler. Using postDelayed doesn't block the thread.

            int[] imageArray = { R.drawable.img_1, R.drawable.img_2,
            R.drawable.img_3, R.drawable.img_4,
            R.drawable.img_5};

            Handler handler = new Handler();
            Runnable runnable = new Runnable() {
                int i = 0;

                public void run() {
                    imageView1.setImageResource(imageArray[i]);
                    i++;
                    if (i > imageArray.length - 1) {
                        i = 0;
                    }
                    handler.postDelayed(this, 5000); //displays every 5 seconds
                }
            };
            handler.postDelayed(runnable, 5000);