Wsrtjtyk

I have a callback interface.

public interface RowCallback {



    void callOnRowAction(String action);

}

My fragment FragmentA is attached to ActivityA in which FragmentA is defined as follows:

class FragmentA extends Fragment implements RowCallback {

  @Override

  void callOnRowAction(String action) {

        . . . Custom implementation . . . 

  }



  ... Other methods . . . 

  @Override

  public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

View view = inflater.inflate(R.layout.fragment_crime_list, container, false);

     mButton = view.findViewById(R.id.my_button);

     mButton.setOnClickListener((view) -> {

        // I want to pass the callback instance (which is FragmentA) to activity B.

        Intent intent = new Intent(getActivity(), ActivityB.class);

        . . .  Some more intent initialisation. . . 

        startActivity(intent);

     });

      return view;

  }





}

ActivityB source Code

public class ActivityB extends AppCompatActivity {





    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_fragment);



        FragmentManager fm = getSupportFragmentManager();

        Fragment fragment = fm.findFragmentById(R.id.fragment_container);

        if (fragment == null) {

            fragment = createFragment(getIntent());

            fm.beginTransaction().add(R.id.fragment_container, fragment).commit();

        }

    }



   private Fragment createFragment(Intent intent) {

      FragmentB fragment = new FragmentB();

      Bundle bundle = new Bundle();

      . . . . initialise bundle . . . 

      // I want to pass the callback instance from the intent to the callback function.

     // In this example, the callback instance would be an instance of fragment A.

      fragment.setArguments(bundle);

     return fragment;

   }

}

In an instance of FragmentB, I want to invoke a call back method should a logical condition be satisfied.I want to return to ActivityA/FragmentA after the callback function has been invoked by calling getActivity().finish();

How can I achieve something like this?

I will split my answer:

1. 
   

   If you want a callback for one time:

   
   
   
   
   
   • Fragment A OnclickListener
     will call to his Activity (lets say A).
   
   
   • Activity A will do
     StartActivityForResult(intent) to Activity B.
   
   
   • Activity B will
     attach Fragment B to himself.
   
   
   • Fragment B OnclickListener will
     update his Activity (B).
   
   
   • Activity B will return IntentResult and Activity A will catch it on onActivityResult.
   
   
   
   


2. 
   

   If you want a callback for multiple times:

   
   
   
   
   
   • You can use the architecture of answer 1 - with Activity communication using LocalBroadcastManager
     An example to Activity communication using LocalBroadcastManager
     
   
   
   
   

Implement function in within fragment which you want get call back after execute

    public void testCallBack(Callback callback) {



    callback.callOnRowAction("callback");



}

Implement this in Activity class

   public void getCallBack() {



    FragmentA.newInstance().testCallBack(new FragmentA.Callback() {

        @Override

        public void callOnRowAction(String action) {

            //you can do something

        }

    });

}

if you want to excute testCallBack method when the function start you can call this inside onCreate method

You could inside the fragment add

if(getParentFragment() instanceof Activity1)

((Activity1) getParentFragment()).setRowCallback(this);

else if(getParentFragment() instanceof Activity2)

((Activity2) getParentFragment()).setRowCallback(this);

the fragment will automatically call the callback of his parent activity