Sending data from nested fragments to parent fragment

Question

I have a Fragment FR1 that contains several Nested Fragments; FRa, FRb, FRc. These

Answer 1

Passing data between fragments can be done with FragmentManager. Starting with Fragment 1.3.0-alpha04, we can use setFragmentResultListener() and setFragmentResult() API to share data between fragments.

Official Documentation

Answer 2

The best way to pass data between fragments is using Interface. Here's what you need to do: In you nested fragment:

public interface OnDataPass {
    public void OnDataPass(int i);
}

OnDataPass dataPasser;

@Override
public void onAttach(Activity a) {
    super.onAttach(a);
    dataPasser = (OnDataPass) a;
}

public void passData(int i) {
    dataPasser.OnDataPass(i);
}

In your parent fragment:

public class Fragment_Parent extends Fragment implements OnDataPass {
...

    @Override
    public void OnDataPass(int i) {
        this.input = i;
    }

    btnOk.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            Fragment fragment = getSupportFragmentManager().findFragmentByTag("0");
            ((Fragment_Fr1) fragment).passData();
        }
    }

}

Answer 3

Instead of using interface, you can call the child fragment through below:

( (YourFragmentName) getParentFragment() ).yourMethodName();

Answer 4

You can use getChildFragmentManager() and find nested fragments, get them and run some methods to retrieve input values

Answer 5

The best way is use an interface:

1. Declare an interface in the nest fragment

   // Container Activity or Fragment must implement this interface
   public interface OnPlayerSelectionSetListener
   {
       public void onPlayerSelectionSet(List<Player> players_ist);
   }
   

2. Attach the interface to parent fragment

   // In the child fragment.
   public void onAttachToParentFragment(Fragment fragment)
   {
       try
       {
           mOnPlayerSelectionSetListener = (OnPlayerSelectionSetListener)fragment;
   
       }
       catch (ClassCastException e)
       {
             throw new ClassCastException(
                 fragment.toString() + " must implement OnPlayerSelectionSetListener");
       }
   }
   
   
   @Override
   public void onCreate(Bundle savedInstanceState)
   {
       Log.i(TAG, "onCreate");
       super.onCreate(savedInstanceState);
   
       onAttachToParentFragment(getParentFragment());
   
       // ...
   }
   

3. Call the listener on button click.

   // In the child fragment.
   @Override
   public void onClick(View v)
   {
       switch (v.getId())
       {
           case R.id.tv_submit:
               if (mOnPlayerSelectionSetListener != null)
               {                
                    mOnPlayerSelectionSetListener.onPlayerSelectionSet(selectedPlayers);
               }
               break;
           }
       }
   

4. Have your parent fragment implement the interface.

    public class Fragment_Parent extends Fragment implements Nested_Fragment.OnPlayerSelectionSetListener
    {
         // ...
         @Override
         public void onPlayerSelectionSet(final List<Player> players_list)
         {
              FragmentManager fragmentManager = getChildFragmentManager();
              SomeOtherNestFrag someOtherNestFrag = (SomeOtherNestFrag)fragmentManager.findFragmentByTag("Some fragment tag");
              //Tag of your fragment which you should use when you add
   
              if(someOtherNestFrag != null)
              {
                   // your some other frag need to provide some data back based on views.
                   SomeData somedata = someOtherNestFrag.getSomeData();
                   // it can be a string, or int, or some custom java object.
              }
         }
    }
   

Add Tag when you do fragment transaction so you can look it up afterward to call its method. FragmentTransaction

This is the proper way to handle communication between fragment and nest fragment, it's almost the same for activity and fragment. http://developer.android.com/guide/components/fragments.html#EventCallbacks

There is actually another official way, it's using activity result, but this one is good enough and common.

Answer 6

Check for instanceOf before getting parent fragment which is better:

if (getParentFragment() instanceof ParentFragmentName) {
  getParentFragment().Your_parent_fragment_method();
}