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Switching Fragments in Master / Detail Mode

I am trying to create an application with a Master / Detail stream using fragments. When you select an item, a part fragment will open, which can then “open” another fragment and add it to the back stack.

I renamed classes to help illustrate what they do.

public class ListOfDetails extends FragmentActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ...
    }

    //Callback method indicating that an item with the given ID was selected.
    public void onItemSelected(String id) {
        // Performing logic to determine what fragment to start omitted

        if (ifTwoPanes()) {
            Fragment fragment = new DetailFragmentType1();
            getSupportFragmentManager().beginTransaction().replace(R.id.aContainer, fragment).commit();
        } else {
            Intent newIntent = new Intent(this, SinglePaneFragmentWrapper.class);
            newIntent.putExtra("id", id);
            startActivity(newIntent);
        }
    }

    // My attempt at making it possible to change displayed fragment from within fragments
    public void changeDetailFragment(Fragment fragment) {
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
        transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
        transaction.addToBackStack(null);
        transaction.replace(R.id.aContainer, fragment);
        transaction.commit();
    }
}

An example of one of the fragments of a part. There are many different fragments that can be created in different circumstances.

public class DetailFragmentType1 extends Fragment {
    private ListOfDetails parent;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Activity a = getActivity();
        if (a instanceof ListOfDetails) {
            parent = (ListOfDetails) a;
        }
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        Button aButton = (Button) getActivity().findViewById(R.id.aButton);
        aButton.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                parent.changeDetailFragment(new SubDetailFragment());
            }
        });
    }
}

If the phone uses a wrapper operation to store the fragment

public class SinglePaneFragmentWrapper extends FragmentActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Duplicate logic must be performed to start fragment
        // Performing logic to determine what fragment to start omitted
        String id = getIntent().getStringExtra("id");
        if(id == "DetailFragmentType1") {
            Fragment fragment = new DetailFragmentType1();
            getSupportFragmentManager().beginTransaction().replace(R.id.aContainer, fragment).commit();
        } else {
            ...
        }
    }
}

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+5
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public interface FragmentChangeListener {
  void onFragmentChangeRequested(Fragment newFragment);
}

ListOfDetails

public class ListOfDetails extends FragmentActivity implements FragmentChangeListener {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ...
}

//Callback method indicating that an item with the given ID was selected.
public void onItemSelected(String id) {
    // Performing logic to determine what fragment to start omitted

    if (ifTwoPanes()) {
        Fragment fragment = new DetailFragmentType1();
        getSupportFragmentManager().beginTransaction().replace(R.id.aContainer, fragment).commit();
    } else {
        Intent newIntent = new Intent(this, SinglePaneFragmentWrapper.class);
        newIntent.putExtra("id", id);
        startActivity(newIntent);
    }
}

// My attempt at making it possible to change displayed fragment from within fragments
public void changeDetailFragment(Fragment fragment) {
    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
    transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
    transaction.addToBackStack(null);
    transaction.replace(R.id.aContainer, fragment);
    transaction.commit();
}

// This is the interface implementation that will be called by your fragments
void onFragmentChangeRequested(Fragment newFragment) {
    changeDetailFragment(newFragment);
}

}


public class DetailFragmentType1 extends Fragment {

    private FragmentChangeListener fragmentChangeListener;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // Actually you might not have an activity here.. you should probably be 
        // doing this in onAttach
        //Activity a = getActivity();
        //if (a instanceof ListOfDetails) {
        //    parent = (ListOfDetails) a;
        //}
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        Button aButton = (Button) getActivity().findViewById(R.id.aButton);
        aButton.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
               // parent.changeDetailFragment(new SubDetailFragment());
               notifyFragmentChange(new SubDetailFragment());
            }
        });
    }

    @Override
    public void onAttach(Activity activity) {
      // This is called when the fragment is attached to an activity..
      if (activity instanceof FragmentChangeListener) {
          fragmentChangeListener = (FragmentChangeListener) activity;
      } else {
         // Find your bugs early by making them clear when you can...
         if (BuildConfig.DEBUG) {
           throw new IllegalArgumentException("Fragment hosts must implement FragmentChangeListener");
         }
      }
    }

    private void notifyFragmentChange(Fragment newFragment) {
      FragmentChangeListener listener = fragmentChangeListener;
      if (listener != null) {
         listener.onFragmentChangeRequested(newFragment);
      }
    }
}

...

public class SinglePaneFragmentWrapper extends FragmentActivity implements FragmentChangeListener {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Duplicate logic must be performed to start fragment
        // Performing logic to determine what fragment to start omitted
        String id = getIntent().getStringExtra("id");
        if(id == "DetailFragmentType1") {
            Fragment fragment = new DetailFragmentType1();
            getSupportFragmentManager().beginTransaction().replace(R.id.aContainer, fragment).commit();
        } else {
            ...
        }
    }
// My attempt at making it possible to change displayed fragment from within fragments
public void changeDetailFragment(Fragment fragment) {
    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
    transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
    transaction.addToBackStack(null);
    transaction.replace(R.id.aContainer, fragment);
    transaction.commit();
}

// This is the interface implementation that will be called by your fragments
void onFragmentChangeRequested(Fragment newFragment) {
    changeDetailFragment(newFragment);
}

}

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, , .

, CJ

+1

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