Activity Passing Data to Fragment through callbacks

Question

I got a situation here .

I have FragmentActivty which holds a Fragment . when i click on a button in Fragment i am going to a Activty . when i reach the activity i do something which will affect the data displayed in Fragment where i came from. So in order to bring that changes in fragment i would like to give a callback from the Activity to Fragment. First i thought of implementing onActivityResult. But i realized it's not what i needed.

Is my approach is wrong?? Please guide me

MyActivity extends FragmentActivity

MyActivity holds

MyFragment extends Fragment

From here i'm going to

SecondActivity extends Activity

from SecondActivity i need to get a callback to MyFragment . Is there anything wrong with my approach ??

EDIT:

 public class MainActivity extends FragmentActivity {
    private FrameLayout frameLayout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        frameLayout = (FrameLayout) findViewById(R.id.framelayout);
         loadFragment();

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);

        return true;
    }

    private void loadFragment() {
        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager
                .beginTransaction();
        MyFragment myFragment = new MyFragment();
        fragmentTransaction.add(R.id.framelayout, myFragment);
        fragmentTransaction.commit();

    }
}

MyFragment.java

public class MyFragment extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_view, container, false);
        Button button = (Button) view.findViewById(R.id.button);
        button.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                callActivity();

            }
        });

        return view;
    }



    private void callActivity() {
        Intent intent = new Intent(getActivity(), SecondActivity.class);
        startActivityForResult(intent, 10);
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
//      super.onActivityResult(requestCode, resultCode, data);
        Log.e("MyFragment Inside", "Onresultttt");
        if (requestCode == 10) {
            if (resultCode == Activity.RESULT_OK) {
                Log.e("Result code", Activity.RESULT_OK + " okkk");
            }
            if (resultCode == Activity.RESULT_CANCELED) {
                Log.e("Result code", Activity.RESULT_CANCELED + "cancelll inside fragment");
            }
        }
    }
}

SecondActivity.java

public class SecondActivity extends Activity {
    private static final String TAG = "second activity";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.secondactivity_view);
    }

    @Override
    public void onBackPressed() {
        // super.onBackPressed();
        Intent intent = new Intent();
        setResult(RESULT_CANCELED, intent);
        Log.e(TAG, "result setted");
        finish();

    }
}

Answer 1

If I understand your situation correctly, then the correct way of handling the communication is to have SecondActivity pass back information to MyActivity, which will in turn configure it's instance of MyFragment directly. You don't want to be accessing Fragments from Activities unless the Fragment is attached to the Activity.

As for how to do the communication, as you suggested, one way of doing it would be through the use of startActivityForResult(). See this answer for more details: How to manage `startActivityForResult` on Android?

Just a note about startActivityForResult(). If you are calling it from the Fragment then your Fragment will receive the result, not your Activity. There are also some other issues with calling startActivityForResult() from a Fragment, so I would generally recommend that you instead call it from the Activity and therefore handle the result from the Activity.

Intent i = new Intent(this, SecondActivity.class);
startActivityForResult(i, INTENT_CODE);

The best practice way of communicating from a Fragment to an Activity is by defining an Interface in the Fragment, which the Activity implements.

public class MyFragment extends Fragment {
    public interface MyFragmentListener() {
        public void onMyFragmentEvent();
    }

    public void startTheActivityForResult() {
        ((MyFragmentListener)getActivity()).onMyFragmentEvent();
    }
}

public class MainActivity extends FragmentActivity implements MyFragmentListener{
    @Override public void onMyFragmentEvent() {

    }
}

The Fragment then simply casts the reference to the Activity it is attached to, knowing that the Activity must implement the Listener, thus allowing you to reuse the Fragment in other Activities.

Answer 2

Refer this question it will help you understand what is happening: onActivityResult is not being called in Fragment