java - 如何停止 Handler Runnable？

Question

我在以下程序中使用处理程序，我想在 i=5 时停止它，但处理程序不会停止并连续运行。

   b1.setOnClickListener(new OnClickListener() {

        public void onClick(View v) {
            handler = new Handler();
           runnable = new Runnable() {
                 public void run() {

                    try {
                        Toast.makeText(getApplicationContext(), "Handler is working", Toast.LENGTH_LONG).show();
                        System.out.print("Handler is working");

                       if(i==5){
                           //Thread.currentThread().interrupt();
                            handler.removeCallbacks(runnable);


                            System.out.print("ok");
                                        Toast.makeText(getApplicationContext(), "ok", Toast.LENGTH_LONG).show();
                        }
                       i++;
                    } catch (Exception e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    } 
                   handler.postDelayed(this, 5000); 

               }
           };
           handler.postDelayed(runnable, 5000);
           //return;
        }
    });

Answer 1

因为您postDelayed()在删除回调后再次调用。请使用此代码：

final Handler handler = new Handler();
final Runnable runnable = new Runnable() {
         public void run() {
               Log.d("Runnable","Handler is working");
               if(i == 5){ // just remove call backs
                    handler.removeCallbacks(this); 
                    Log.d("Runnable","ok");
                } else { // post again
                    i++;
                    handler.postDelayed(this, 5000); 
                }
       }
   };

//now somewhere in a method
 b1.setOnClickListener(new OnClickListener() {
    public void onClick(View v) {
        handler.removeCallbacks(runnable); 
        handler.postDelayed(runnable, 5000); 
    }
});

Answer 2

protected void onStop() {
    super.onStop();
    handler.removeCallbacks(runnable);
}

你可以像这样阻止它

Answer 3

我找到了一个适合我的解决方案。这是一个代码示例，我希望计时器停止，但我看到它还活着，即使我没有活动：

boolean bFlagForceExit = false; 
Handler timerHandler = new Handler();
private   Runnable timerRunnable = new Runnable() {
    @Override
    public void run() {

        if  (bFlagForceExit )
    MyProcessForExit(); 

        if (bSomeflagForRunAction)
            RunProcess();

        timerHandler.postDelayed(this, MILISEGUNDOS_ESPERA);        }
};


private void  MyProcessForExit()
{
    timerHandler.removeCallbacks(timerRunnable);
// close activity or whatever
finish();
}


private void  RunProcess()
{
   // action that i do when tick 
// time to leave or stop
bFlagForceExit = true;
}

然后我发现如果removeCallbacks(timerRunnable)为其他线程调用这将有效，所以，我解决了这样的问题。

boolean bFlagForceExit = false; 
Handler timerHandler = new Handler();
private   Runnable timerRunnable = new Runnable() {
    @Override
    public void run() {

        if  (bFlagForceExit )
        {
    // add a thred for run your stop handler
            new Thread(new Runnable() {
                public void run() {
                    SalirDeProceso();
                }
            }).start();
        }

        if (bSomeflagForRunAction)
            RUnProcess();

        timerHandler.postDelayed(this, MILISEGUNDOS_ESPERA);        }
};

Answer 4

刚看到这个问题。我会改用 CountDownTimer() 。总共运行 5 秒，每秒运行一次：

new CountDownTimer(5000, 1000) {
    public void onTick(long milsecRemain) {
        // Code to run every second
        Log.i("Seconds left", String.valueOf(milsecRemain/1000));
}
    public void onFinish() {
        // 10 seconds have passed
    }
}.start();