Android Handler的postDelayed()关闭的方法及遇到问题

new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                showPaySuccessDialog.dismiss();
            }
        }, 1000);

//todo 此处检测
  new Handler().postDelayed(new Runnable() {
                @Override
                public void run() {
                    if (!MediaplayerUtil.isPlaying()) {
                        MediaplayerUtil.playMusic(context, R.raw.pay_tips);
                    }
                }
            }, 15 * 1000);

Handler handler=new Handler();

Runnable runnable=new Runnable(){
   @Override
   public void run() {
	    // TODO Auto-generated method stub
   	    //要做的事情，这里再次调用此Runnable对象，以实现每两秒实现一次的定时器操作
    handler.postDelayed(this, 2000);
   }
};

handler.postDelayed(runnable, 2000);

handler.removeCallbacks(runnable);

//初始化先
 private Handler handler;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        handler = new Handler();
 
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                // 这个是循环 间隔3s弹一次Toast
                handler.postDelayed(this, 3 *1000);
                Toast.makeText(this, "延时5s", Toast.LENGTH_SHORT).show();
            }
        };
        // 延迟2s弹Toasat
        handler.postDelayed(runnable,2000);
    }
 
    @Override
    protected void onDestroy() {
        super.onDestroy();
        //在页面结束时 清空队列消息
        if (handler != null) {
            handler.removeCallbacksAndMessages(null);
            handler = null;
        }
    }