How to Implement Onfragmentinteractionlistener

How to implement OnFragmentInteractionListener

Answers posted here did not help, but the following link did:

http://developer.android.com/training/basics/fragments/communicating.html

Define an Interface

public class HeadlinesFragment extends ListFragment {
    OnHeadlineSelectedListener mCallback;

    // Container Activity must implement this interface
    public interface OnHeadlineSelectedListener {
        public void onArticleSelected(int position);
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);

        // This makes sure that the container activity has implemented
        // the callback interface. If not, it throws an exception
        try {
            mCallback = (OnHeadlineSelectedListener) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                    + " must implement OnHeadlineSelectedListener");
        }
    }

    ...
}

For example, the following method in the fragment is called when the user clicks on a list item. The fragment uses the callback interface to deliver the event to the parent activity.

@Override
public void onListItemClick(ListView l, View v, int position, long id) {
    // Send the event to the host activity
    mCallback.onArticleSelected(position);
}

Implement the Interface

For example, the following activity implements the interface from the above example.

public static class MainActivity extends Activity
        implements HeadlinesFragment.OnHeadlineSelectedListener{
    ...

    public void onArticleSelected(int position) {
        // The user selected the headline of an article from the HeadlinesFragment
        // Do something here to display that article
    }
}

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Update for API 23: 8/31/2015

Overrided method onAttach(Activity activity) is now deprecated in android.app.Fragment, code should be upgraded to onAttach(Context context)

@Override
public void onAttach(Context context) {
    super.onAttach(context);
}


@Override
public void onStart() {
    super.onStart();
    try {
        mListener = (OnFragmentInteractionListener) getActivity();
    } catch (ClassCastException e) {
        throw new ClassCastException(getActivity().toString()
                + " must implement OnFragmentInteractionListener");
    }
}

must implement OnFragmentInteractionListener error in Android Studio

in this case you should implement your listener in your activity not in a fragment.

public class LauncherActivity extends AppCompatActivity implements Tab1.OnFragmentInteractionListener

This is because Context passed in your fragment comes from activity and not fragment.

If you want HomeFragment to receive events. What you can do is create public setter method for listeners in Tab-fragments.

public void setInteractionListener(OnFragmentInteractionListener mListener){
  this.mListener = mListener;
}

Must implement OnFragmentInteractionListener()

You need to make the parent activity implement OnFragmentInteractionListener and override the methods provided by that interface.

class MyActivity implements OnFragmentInteractionListener

This is where your code is crashing, your activity probably does not implement the metioned interface and because of that the crash happens when the fragment is attached:

@Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context instanceof OnFragmentInteractionListener) {
            mListener = (OnFragmentInteractionListener) context;
        } else {
            throw new RuntimeException(context.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

ERROR: must implement OnFragmentInteractionListener

The OnFragmentInteractionListener interfaces in both of your Fragments contain a method with the same signature, and MainActivity is implementing one method to try to cover both interfaces.

Change the signature of one or both of the methods, then implement both methods in MainActivity. For example:

NavFragment

    public interface OnFragmentInteractionListener {
        public void onNavFragmentInteraction(String string);
    }

ContentFragment

    public interface OnFragmentInteractionListener {
        public void onContentFragmentInteraction(String string);
    }

MainActivity

    @Override
    public void onNavFragmentInteraction(String string) {
        // Do stuff
    }

    @Override
    public void onContentFragmentInteraction(String string) {
        // Do different stuff
    }

How to add OnFragmentInteractionListener in Navigation Drawer Activity in Kotlin?

Apparently, You are trying to implement communication mechanism between fragment and activity via OnFragmentInteractionListener interface so use

class MainActivity : AppCompatActivity(),
       FirstFragment.OnFragmentInteractionListener,
       NavigationView.OnNavigationItemSelectedListener {
     // .. other code

     override fun onFragmentInteraction(uri: Uri) {
      // TODO Implement
     }


}

and override methods

MainActivity must implement OnFragmentInteractionListener

public class MainActivity extends AppCompatActivity
                implements NavigationView.OnNavigationItemSelectedListener, OnFragmentInteractionListener {

    .......
}

Press alt +enter on OnFragmentInteractionListener to import it in mainActivity

Android Studio getting Must implement OnFragmentInteractionListener

Remove onAttach method from your Fragment, then it'll be okay.

BottomNavigationView in a fragment, getting a 'must implement OnFragmentInteractionListener' error

Sounds like you copy/pasted some code / left in part of some auto-generated sample code. If you're not using the OnFragmentInteractionListener interface, just remove that code.

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