Passing data between a fragment and its container activity

Easiest Approach but not Recommended

You can access activity data from fragment:

Activity:

public class MyActivity extends Activity {

    private String myString = "hello";

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

    public String getMyData() {
        return myString;
    }
}

Fragment:

public class MyFragment extends Fragment {

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

        MyActivity activity = (MyActivity) getActivity();
        String myDataFromActivity = activity.getMyData();
        return view;
    }
}

Try using interfaces.

Any fragment that should pass data back to its containing activity should declare an interface to handle and pass the data. Then make sure your containing activity implements those interfaces. For example:

JAVA

In your fragment, declare the interface...

public interface OnDataPass {
    public void onDataPass(String data);
}

Then, connect the containing class' implementation of the interface to the fragment in the onAttach method, like so:

OnDataPass dataPasser;

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

Within your fragment, when you need to handle the passing of data, just call it on the dataPasser object:

public void passData(String data) {
    dataPasser.onDataPass(data);
}

Finally, in your containing activity which implements OnDataPass...

@Override
public void onDataPass(String data) {
    Log.d("LOG","hello " + data);
}

---

KOTLIN

Step 1. Create Interface

interface OnDataPass {
    fun onDataPass(data: String)
}

Step 2. Then, connect the containing class' implementation of the interface to the fragment in the onAttach method (YourFragment), like so:

lateinit var dataPasser: OnDataPass

override fun onAttach(context: Context) {
    super.onAttach(context)
    dataPasser = context as OnDataPass
}

Step 3. Within your fragment, when you need to handle the passing of data, just call it on the dataPasser object:

fun passData(data: String){
    dataPasser.onDataPass(data)
}

Step 4. Finally, in your activity implements OnDataPass

class MyActivity : AppCompatActivity(), OnDataPass {}

override fun onDataPass(data: String) {
    Log.d("LOG","hello " + data)
}

In your fragment you can call getActivity().

This will give you access to the activity that created the fragment. From there you can obviously call any sort of accessor methods that are in the activity.

e.g. for a method called getResult() on your Activity:

((MyActivity) getActivity()).getResult();

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    Bundle b = getActivity().getIntent().getExtras();
            wid = b.getString("wid");
            rid = b.getString("rid");
            View view = inflater.inflate(R.layout.categoryfragment, container, false);
    return view;
 }