removeCallbacks not stopping runnable

Question

I am calling from a method:

myHandler.postDelayed(mMyRunnableHide, 6000);

which calls:

public Runnable mMyRunnableHide = new Runnable()
{

    public void run()
    {
        mTextDisplay.setText("");
        DisplayX();
    }
 };

if a button on screen is clicked I want to stop the runnable:

   Button next = (Button) findViewById(R.id.Breaction);
    next.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {

            myHandler.removeCallbacks(mMyRunnableHide);

            mTextDisplay.setText("");
            DisplayX();
            }
        });   
    }

the removecallbacks is not stopping the runnable. What am I doing wrong? Am I using the correct method? I just want the runnable to "Not Run" when the user clicks the button.

Thanks for any help.

Answer 1

It appears to me that removeCallbacks(..) only stops pending messages (Runnables). If your runnable has already started, then there's no stopping it (at least not this way).

Alternatively, you can extend the Runnable class and give it some kind of kill switch like this:

public class MyRunnable implements Runnable
{
   private boolean killMe = false;

   private void run()
   {
      if(killMe)
         return;

      /* do your work */
   }

   private void killRunnable()
   {
      killMe = true;
   }
}

This will only prevent it from starting, but you could occasionally check killMe and bail out. If you are looping the runnable (like some kind of background thread) you can say:

while(!killMe) {
   /* do work */
}

Hope this helps

EDIT I just wanted to post an update on this. Since this original post, Google has come up with a great class called AsyncTask that handles all of this stuff for you. Anyone reading this really should look into it because it is the correct way of doing things.

You can read about it here