再按一次退出程序

private void exit() {
         if(!isExit) {
             isExit = true;
             Toast.makeText(this, "再按一次退出程序", Toast.LENGTH_SHORT).show();
             new Timer().schedule(new TimerTask() {
                 
                 @Override
                 public void run() {
                     isExit = false;
                 }
             }, 2000);
         } else {
             finish();
         }
     }