I would like to write an activity that after clicking on a button turns off the screen and then turns it back on after 2 secs. I tried using the following code in order to power off the screen:

WindowManager.LayoutParams lp = getWindow().getAttributes();
lp.screenBrightness = 0/(float)255;
getWindow().setAttributes(lp);

But it would only take effect when then onClick function returns. I tried running it into a handler but with no success. I need to find a way to force the setting to get applied before the function returns so that I can call the power on function 2 secs later on the same onClick call.

I also found it very hard to wakeup the device afterwards. While this code works if I power off the screen using the physical button it doesn't seem to work when the phone is powered off using the technique described previously.

PowerManager pm = (PowerManager)this.getSystemService(Context.POWER_SERVICE); 
PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.FULL_WAKE_LOCK|PowerManager.ACQUIRE_CAUSES_WAKEUP | 
PowerManager.ON_AFTER_RELEASE ,"Dev Tag");
try
{
    wl.acquire();
    wl.release();
}
catch (Exception e)
{
    Toast.makeText(this, e.getMessage(),20).show();
}

Thanks you in advance for your help!