Implementation of "Press the return key again to exit the program" in Android

privatelong exitTime = 0;@Overridepublicboolean onKeyDown(int keyCode, KeyEvent event) {if(keyCode == KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_DOWN){   if((System.currentTimeMillis()-exitTime) > 2000){              Toast.makeText(getApplicationContext(), "再按一次退出程序", Toast.LENGTH_SHORT).show();                                            exitTime = System.currentTimeMillis();           } else {            finish();            System.exit(0);        }returntrue;       }returnsuper 


 
    
        






         

     .onKeyDown(keyCode, event);
}