No methods in AsyncTask is ever called

Question

I have an implementation of AsyncTask in my application, but I have a problem.

Here is my implementation of AsyncTask:

public class AsyncTaskPost extends AsyncTask<URL, Void, Void> {

    private View mView;
    private ProgressBar mProgressbar;
    private Context mContext;

    public AsyncTaskPost(View view, Context context){
        mView = view;
        mProgressbar = (ProgressBar)mView.findViewById(R.id.progressPostUser);
        mContext = context;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        mProgressbar.setVisibility(View.VISIBLE);
    }

    @Override
    protected Void doInBackground(URL... urls) {
        try{
            Thread.sleep(5000);
            return null;
        }
        catch (Exception ex) {
            return null;
        }
    }

    @Override
    protected void onPostExecute(Void aVoid) {
        Toast.makeText(mContext, "Finished", Toast.LENGTH_SHORT);
    }

    @Override
    protected void onProgressUpdate(Void... values) {
        mProgressbar.setVisibility(View.VISIBLE);
    }

    @Override
    protected void onCancelled() {
        super.onCancelled();
    }
}

Here is how I call it:

public void onSaveClicked(User user) {
    try {
        String nameTest = user.get_name();
        String surnameTest = user.get_surname();

        new AsyncTaskPost(mView, mContext).execute(new URL("www.blahblah.com"));
        //new AsyncTaskPost(mView, mContext).executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, new URL("www.blahblah.com"));
    }
    catch (Exception ex) {

    }

}

When I debug the app, I can step into the constructor, but after that, none of the onPreStart, 'doInBackground' is called?

Why is this happening?

`new AsyncTaskPost(mView, mContext).execute(new URL("www.blahblah.com"));`. It is not started/executed in that way. Change to `new AsyncTaskPost(mView, mContext).execute(new URL("www.blahblah.com")).execute();` — greenapps, Feb 09 '18 at 17:17
Can you step into an `execute` method with debugger? what happens there? — M. Prokhorov, Feb 09 '18 at 17:28
@greenapps your comment is wrong, you don't need to call execute twice, it is the same method with or without arguments — Marcos Vasconcelos, Feb 09 '18 at 17:45

score 1 · Accepted Answer · edited Jun 20 '20 at 09:12

1

Nothing runs because your code causes a MalformedURLException

as per importing your code into Android Studio I got:

 java.net.MalformedURLException: no protocol: www.blahblah.com

If you clean this up it will work just fine, However you have a few significant problems with your design.

An AsyncTask does not and should not use Context if it can be avoided, especially given that AS will tell you it is creating a leak.

Use Callbacks (i.e interface with some functions like showToast(), or displayProgress(Integer value)) to avoid having to do things such as show a Toast... which here, you have not called show() on your Toast anyways.

In addition to not passing Context you should definitely not pass your View into your AsyncTask because what happens when your View is gone but AsyncTask calls onPostExecute(Void aVoid).... the app will crash. (same can be said if Context is no longer valid i.e null)

see using WeakReference if you can't remove the dependencies.

Make these changes and you will be all set.

Good Luck and Happy Coding!

edited Jun 20 '20 at 09:12

Community

1
1

answered Feb 09 '18 at 17:30

kandroidj

13,784
5
64
76

Thanks for all the pointers. How am I supposed to access, for instance, my ProgressBar without passing the View to AsyncTask, as used in Android's examples? If I pass in a valid URL, I can see the Progressbar. – android_monstertjie Feb 09 '18 at 17:58
@android_monstertjie you can use Intent and BroadcastReceivers or create an interface as per my comment above and pass along the reference to that interface into the AsyncTask and implement the interface in the Activity or Fragment hosting the View. – kandroidj Feb 09 '18 at 18:02
I see what yo mean, with the following example: https://stackoverflow.com/questions/994840/how-to-create-our-own-listener-interface-in-android Thanks – android_monstertjie Feb 09 '18 at 18:09

No methods in AsyncTask is ever called

1 Answers1