Sending data to the container activity

Question

I have this issue of sending some data back and forth between a fragment and its container activity, I succeeded in doing it. What puzzles me is sending my data from the fragment to the activity, at first I implemented OnResume(), OnStop() and sent the data through an intent and that created an infinite loop so I removed them. Then I did setRetainInstance(true) and it worked and gave me the wanted behavior.

My Question is How my data are really being sent and where in the fragment lifecycle ?

https://developer.android.com/training/basics/fragments/communicating.html — Nongthonbam Tonthoi, May 05 '17 at 10:30
i answered on this link. you can check on this. http://stackoverflow.com/questions/43277624/call-fragment-b-from-fragment-a-using-viewpager-tabs/43278790#43278790 — Noorul, May 05 '17 at 10:30
you can check this link also http://stackoverflow.com/questions/12739909/send-data-from-activity-to-fragment-in-android/38741476#38741476 — Noorul, May 05 '17 at 10:31
I am not looking for the how to do it, I am not implementing any of the lifecycle methods nor intents, nothing I just specified the `setRetainState(true)`, Why the data is being sent and how I want to undrestand the logic behind it — MeknessiHamida, May 05 '17 at 10:40
to add some context in the container activity its `new Fragment()` each time I enter my fragment. — MeknessiHamida, May 05 '17 at 10:42

score 1 · Answer 1 · edited May 23 '17 at 12:26

1

The Right approach is to use Interfaces. Don't use onStop or setRetainInstance()

See this. It will solve you problem. Pass data from fragment to actvity

edited May 23 '17 at 12:26

Community

1
1

answered May 05 '17 at 10:28

Ishaan Kumar

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score 1 · Answer 2 · answered May 05 '17 at 13:14

You can also achieve this by using Interface, using an EventBus like LocalBroadcastManager, or starting a new Activity with an Intent and some form of flag passed into its extras Bundle or something else.

Here is an example about using Interface:

1. Add function sendDataToActivity() into the interface (EventListener).

//EventListener.java

public interface EventListener {

    public void sendDataToActivity(String data);
}

2. Implement this functions in your MainActivity.

// MainActivity.java

public class MainActivity extends AppCompatActivity implements EventListener {

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

    @Override
    public void sendDataToActivity(String data) {
        Log.i("MainActivity", "sendDataToActivity: " + data);
    }
}

3. Create the listener in MyFragment and attach it to the Activity.

4. Finally, call function using listener.sendDataToActivity("Hello World!").

// MyFragment.java 

public class MyFragment extends Fragment {

    private EventListener listener;

    @Override
    public void onAttach(Activity activity)
    {
        super.onAttach(activity);
        if(activity instanceof EventListener) {
            listener = (EventListener)activity;
        } else {
            // Throw an error!
        }
    }

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

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

        // Send data
        listener.sendDataToActivity("Hello World!");

        return view;
    }

    @Override
    public void onDetach() {
        super.onDetach();

        listener = null;
    }
}

Hope this will help~

+1 for the effort and explanation, am aware that I can do it using an interface, but my problem is to understand how I did it now ? does the `setRetainState(true)` is the one doing it for me althoug am making a new instance of myfragment each time or what ? — MeknessiHamida, May 05 '17 at 13:17

Sending data to the container activity

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