倒计时最简单的使用

Handler handler = new Handler() {
    public void handleMessage(android.os.Message msg) {

              a--;
              js.setText(a+"");
              if (a<=0){

                  Intent intent = new Intent(MainActivity.this,MainInterface.class);

                  startActivity(intent);

              }
        handler.sendEmptyMessageDelayed(0, 1000);//定时1秒发一次
    }
};

handler.sendEmptyMessageDelayed(0, 1000); 调用一下