Question

Why is the try block executed first, i want the colors to change first and then it should sleep fo 5000ms. i mean the system sleeps before the colors changes.
private OnClickListener CheckAnswer =new OnClickListener() {

    public void onClick(View arg0) {
        // TODO Auto-generated method stub

        disableButtons();
        Button incoming=(Button) arg0;
        if(incoming.getText().toString().equals(Q.getAnswer()))
        {
            incoming.setBackgroundColor(Color.GREEN);
            correct++;
            score+=15;
        }
        else 
        {
            incoming.setBackgroundColor(Color.RED);
            wrong++;
            if(C1.getText().toString().equals(Q.getAnswer()))
                C1.setBackgroundColor(Color.GREEN);
            else if(C2.getText().toString().equals(Q.getAnswer()))
                C2.setBackgroundColor(Color.GREEN);
            else if(C3.getText().toString().equals(Q.getAnswer()))
                C3.setBackgroundColor(Color.GREEN);
            modifyScore();

        }
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        questionGenerator();
    }
};`

Answer 1

I’d guess because the properties of the view are updated, but the screen redraw is stuck behind your sleep. DO NOT sleep on the main thread.

Instead create a Handler in the onCreate of your Activity and post a delayed Runnable to it.

private Handler mHandler;
protected void onCreate(Bundle savedInstanceState) {
    mHandler = new Handler();
}
...
private OnClickListener CheckAnswer = new OnClickListener() {
     public void onClick(View view) {
       // fix up view
       mHandler.postDelayed(new Runnable() {
           @Override
           public void run() {
               questionGenerator();
           }
       }, 10000);
   }
}