CODEWITHSUNDEEP
androidandroid-asynctask
user
user

Reputation: 673

How to stop asynctask thread in android?

I want to stop a AsyncTask thread from another AsyncTask thread. I have tried like new AsyncTask.cancel(true) to stop the background process but it didn't stop.

Could any one help me on this?

Upvotes: 60

Views: 108165

Answers (6)

Yashwanth Kumar
Yashwanth Kumar

Reputation: 29141

declare your asyncTask in your activity:

private YourAsyncTask mTask;

instantiate it like this:

mTask = new YourAsyncTask().execute();

kill/cancel it like this:

mTask.cancel(true);

Upvotes: 114

Pratik Butani
Pratik Butani

Reputation: 62419

You may also have to use it in onPause or onDestroy of Activity Life Cycle:

//you may call the cancel() method but if it is not handled in doInBackground() method
if (loginTask != null && loginTask.getStatus() != AsyncTask.Status.FINISHED)
    loginTask.cancel(true);

where loginTask is object of your AsyncTask

Thank you.

Upvotes: 12

Devesh Singh
Devesh Singh

Reputation: 13

u can check onCancelled() once then :

protected Object doInBackground(Object... x) {

while (/* condition */) {
  if (isCancelled()) break;
}
return null;

}

Upvotes: -3

user2758776
user2758776

Reputation: 431

You can't just kill asynctask immediately. In order it to stop you should first cancel it:

task.cancel(true);

and than in asynctask's doInBackground() method check if it's already cancelled:

isCancelled()

and if it is, stop executing it manually.

Upvotes: 7

IanB
IanB

Reputation: 3489

I had a similar problem - essentially I was getting a NPE in an async task after the user had destroyed the fragment. After researching the problem on Stack Overflow, I adopted the following solution:

volatile boolean running;

public void onActivityCreated (Bundle savedInstanceState) {

    super.onActivityCreated(savedInstanceState);

    running=true;
    ...
    }


public void onDestroy() {
    super.onDestroy();

    running=false;
    ...
}

Then, I check "if running" periodically in my async code. I have stress tested this and I am now unable to "break" my activity. This works perfectly and has the advantage of being simpler than some of the solutions I have seen on SO.

Upvotes: 1

DecodeGnome
DecodeGnome

Reputation: 1809

The reason why things aren't stopping for you is because the process (doInBackground()) runs until it is finished. Therefore you should check if the thread is cancelled or not before doing stuff:

if(!isCancelled()){
// Do your stuff
}

So basically, if the thread is not cancelled, do it, otherwise skip it :) Could be useful to check for this some times during your operation, especially before time taking stuff.

Also it could be useful to "clean up" alittle in

onCancelled();

Documentation for AsyncTask:

http://developer.android.com/reference/android/os/AsyncTask.html

Hope this helps!

Upvotes: 22

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