issue with calling Fragment class' method

Question

I have a class "HomeActivity", which is as follows:

        public class HomeActivity extends FragmentActivity implements OnClickListener {

            @Override
            protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                FragmentManager fm = getSupportFragmentManager();

                // Create the list fragment and add it as our sole content.
                if (fm.findFragmentById(android.R.id.content) == null) {
                    HomeFragment list = new HomeFragment();
                    fm.beginTransaction().add(android.R.id.content, list).commit();

                }
            }
        public static class HomeFragment extends Fragment {

        webServiceTask = WebServiceTask.getInstance(
                                    getActivity(), Constants.METHOD_NAME_PRODUCTS,
                                    Constants.PRODUCT_NAME, null);

public  void Work() {}
    }
    }

I have another class WebServiceTask, which is as follows:

  final public class WebServiceTask extends AsyncTask<String, String, String> {
    private WebServiceTask(final Activity activity, final String methodName,
                final String productName, final String addInfo[]) {
            super();
            this.activity = activity;
            this.methodName = methodName;
            this.productName = productName;
            this.addInfo = addInfo;
        }
public static WebServiceTask getInstance(final Activity activity,
            final String methodName, final String productName,
            final String additionalInfo[]) {
        webServiceTask = new WebServiceTask(activity, methodName, productName,
                additionalInfo);
        return webServiceTask;
    }
    protected void onPostExecute() {

    // Here I am trying to call the work() method in HomeFragment, How can I do that?
    }

My question is how can i call the work() method in HomeFragment class from onPostExecute().

work method is in HomeFragment class. Also i have activity variable. — Rookie
– Rookie, Commented Dec 13, 2013 at 10:45

Filip Zymek · Accepted Answer · 2013-12-13 23:25:20Z

I would propose making a listener for you task, and invoke its method in post execute. It will geve you a lot more flexibility and control on what you want to deafter the task finishes. Here is sample code I would use:

public class MyTask extend AsyncTask<Void, Void, Boolean> {

    public interface MyTaskListener {
         void onSuccess();
         void onFailure();
         void onError(Throwable t);
    }

    private Throwable error;
    private MyTaskListener listener;


    public MyTask(MyTaskListener listener) {
          this.listener = listener;
    }

    @Overrride
    public Boolean doInBackground(Void... params) {

        try {
            if (workCompleted()) { 
                //work completed without error - return true
                return Boolean.TRUE;
            } else {
                //work failed to complete - return false
                return Boolean.FALSE;
            }
        } catch(Exception e) {
            //unexpected error  happened - remember error and return null
            this.error = e;
            return null;
        }  


    }


    @Override
    public void onPostExecute(Boolean result){
         if (!isCancelled()) { //you only want to process if task wasn't cancelled

             if (this.error != null && result == null) { //we have error, process it
                 if (listener != null) {
                     listener.onError(this.error);
                 }
             }

             if (Boolean.FALSE.equals(result)) { //we have faile, process it
                 if (listener != null) {
                     listener.onFail();
                 }
             }

             if (Boolean.TRUE.equals(result)) { //we have success
                 if (listener != null) {
                     listener.onSuccess();
                 }
             }


         }
    }


}

And then, in you activit/fragment/service/ use something like this:

public class MyActivity extends Activity {


    private void someInstanceMethod() {/ *do your work here */}

    @Override
    public void onCreate(Bundle savedInstanceState) {

          //setup ui, or do whatever you need

          //create MyAsyncTask with proper listener
          MyAsyncTask task = new MyAsyncTask(new MyAsyncTask.MyAsyncTaskListener() {

              @Override
              public void onSuccess() {
                  //call your instance method here
                  someInstanceMethod();

              }

              @Override
              public void onFailure() {
                  //process fail
              }

              @Override
              public void onError() {
                  //process error
              }


          });



    } 

}

SoulRayder · Accepted Answer · 2013-12-13 10:53:25Z

0

This is one method. I don't know if it is the best one:

Make work function as public static void. Call it from Asynctask onpostexecute as

HomeActivity.Work();

Edit: One more way( again not sure if this is the best way):

If you cant make this work, consider putting your asynctask class inside the home activity class

edited Dec 13, 2013 at 10:53

answered Dec 13, 2013 at 10:44

SoulRayder

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1 Comment

Rookie Over a year ago

cant make that static. I am using click listeners in the method

Rachit Mishra · Accepted Answer · 2013-12-13 11:07:29Z

0

Well using the FragmentManger findFragmentById() or findFragmentByTag() you can get an instance of the current fragment and call your fragment method.

answered Dec 13, 2013 at 11:07

Rachit Mishra

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2 Comments

Rookie Over a year ago

How can i get the Id in my case?

Rachit Mishra Over a year ago

Try to bring the AsyncTask as inner class inside HomeActivity, make the FragmentManager a class variable, now you have access to fragment manager anywhere you want.

Sangeet Suresh · Accepted Answer · 2017-02-26 02:50:26Z

Create an interface file

public interface AsynAction
{
  public void Work();
}

Implements AsynAction in HomeActivity

public class HomeActivity extends FragmentActivity implements OnClickListener,AsyncAction {

            @Override
            protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                FragmentManager fm = getSupportFragmentManager();

                // Create the list fragment and add it as our sole content.
                if (fm.findFragmentById(android.R.id.content) == null) {
                    HomeFragment list = new HomeFragment();
                    fm.beginTransaction().add(android.R.id.content, list).commit();

                }
            }
        public static class HomeFragment extends Fragment {

        webServiceTask = WebServiceTask.getInstance(
                                    getActivity(), Constants.METHOD_NAME_PRODUCTS,
                                    Constants.PRODUCT_NAME, null);
@Override
public  void Work() 
          {
          }
    }
    }

Then make changes in you asynctask to receive asyncAction object as reference

final public class WebServiceTask extends AsyncTask<String, String, String> {
    private WebServiceTask(final AyscAction asycAction,final Activity activity, final String methodName,
                final String productName, final String addInfo[]) {
            super();
            this.activity = activity;
            this.asycAction=asycAction;
            this.methodName = methodName;
            this.productName = productName;
            this.addInfo = addInfo;
        }
public static WebServiceTask getInstance(final AyscAction asycAction,final Activity activity,
            final String methodName, final String productName,
            final String additionalInfo[]) {
        webServiceTask = new WebServiceTask(asycAction,activity, methodName, productName,
                additionalInfo);
        return webServiceTask;
    }
    protected void onPostExecute() {

    // You can call work from here
       if(asynAction!=null)
          asyncAction.Work();
    }

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