Why does the color of the layout not change only after “sleep”?

Question

Android

I would like to make the layout be green for a second, and then turn white. But it turns out that the color does not change at the beginning, but the dream works. How to make it work??

((RelativeLayout)findViewById(R.id.rel_layout)).setBackgroundColor(getResources().getColor(android.R.color.holo_green_dark));
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
      ((RelativeLayout)findViewById(R.id.rel_layout)).setBackgroundColor(getResources().getColor(android.R.color.white));

Answer 1

Call sleep on another thread. For example, through AsyncTask.