IssueTracker

Calling addToBackStack() doesn't seem to have any effect when called on a FragmentTransaction created by calling getChildFragmentManager().beginTransaction() on a Fragment. When a nested Fragment is created and added to the back stack, pressing Back button closes the Activity. Issue reproduces both on Android 4.2 and the compatibility library.

Expected behavior: Pressing Back button should pop the parent Fragment's back stack.

The code is:

MainActivity.java

package com.example.nestedfragmentsbug;

import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTransaction;

public class MainActivity extends FragmentActivity {

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

                HostFragment fragment = new HostFragment();
                FragmentTransaction transaction = getSupportFragmentManager()
                                .beginTransaction();
                transaction.add(R.id.host, fragment, HostFragment.HOST_FRAGMENT_TAG);
                transaction.commit();
        }
}

HostFragment.java

package com.example.nestedfragmentsbug;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;

public class HostFragment extends Fragment implements OnClickListener {

        public static final String HOST_FRAGMENT_TAG = "host_fragment";

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                        Bundle savedInstanceState) {
                View root = inflater.inflate(R.layout.fragment_host_layout, container,
                                false);
                ((Button) root.findViewById(R.id.host_btn)).setOnClickListener(this);
                return root;
        }

        @Override
        public void onClick(View v) {
                if (v.getId() == R.id.host_btn) {
                        NestedFragment fragment = new NestedFragment();
                        FragmentTransaction transaction = getChildFragmentManager()
                                        .beginTransaction();
                        transaction.add(R.id.host_layout, fragment);
                        transaction.addToBackStack(HOST_FRAGMENT_TAG);
                        transaction.commit();
                }
        }
}

NestedFragment.java

package com.example.nestedfragmentsbug;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class NestedFragment extends Fragment {

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                        Bundle savedInstanceState) {
                return inflater.inflate(R.layout.fragment_nested_layout, container,
                                false);
        }
}