How to stop a series of postDelayed handlers

Question

I have a series of postDelayed handlers. I'm having trouble installing mathode, which stops the handlers when the user clicks the stop button anytime they want.

I would be grateful for any help that anyone can provide. Thanks

while (!lessonIsRunning) { Handler handler0 = new Handler(); handler0.postDelayed(new Runnable() { @Override public void run() { plate1.setVisibility(ImageView.VISIBLE); plate2.setVisibility(ImageView.VISIBLE); plate3.setVisibility(ImageView.VISIBLE); } }, 6000); Handler handler1 = new Handler(); handler1.postDelayed(new Runnable() { @Override public void run() { apples1.setVisibility(ImageView.VISIBLE); } }, 9000); Handler handler2 = new Handler(); handler2.postDelayed(new Runnable() { @Override public void run() { plus1.setVisibility(TextView.VISIBLE); } }, 9250); } public void stopLesson(View V){ } 

Answer 1

instead of writing the Runnable task in an anonymous way, you should define it with a name, so later you will have a link to it for deletion:

 //there is no need for multiple handlers //handler must be declared outside all functions, in order for you to use it everywhere. Handler handler = new Handler(); Runnable myFirstTask = new Runnable (){ @Override public void run() { plate1.setVisibility(ImageView.VISIBLE); plate2.setVisibility(ImageView.VISIBLE); plate3.setVisibility(ImageView.VISIBLE); } }; Runnable mySecondTask = new Runnable(){ @Override public void run() { plus1.setVisibility(TextView.VISIBLE); } }; Runnable myThirdTask = new Runnable(){ @Override public void run() { apples1.setVisibility(ImageView.VISIBLE); } } //you can put different tasks on the same handler object while (!lessonIsRunning) { handler.postDelayed(myFirstTask,6000); handler.postDelayed(mySecondTask,9250); handler.postDelayed(myThirdTask,9000); } public void stopLesson(View V){ //notice that you don't need these, because the handlers are not recursive //you don't have lines "handler.postDelayed(sameTask,someTime);" //in your run Method of the runnable if(handler!=null){ handler.removeCallbacks(myFirstTask); handler.removeCallbacks(mySecondTask); handler.removeCallbacks(myThirdTask); //if this method is inside onPause or onDestroy add this line as well: handler=null; } } 

Answer 2

You can give

 handler0.removeCallbacksAndMessages(null); handler1.removeCallbacksAndMessages(null); handler2.removeCallbacksAndMessages(null); 

try it. The document says that when you send a null token, all callbacks and the message are deleted.