Empty tab when parent is not an activity but a fragment

Question

I've got a running Android App with a Navigation Drawer Activity. For every menu item, I wanted to implement a separate Fragment, so I can use the same toolbar and drawer menu. Now one of this Fragments should contain a view with 3 Tabs (3 Fragments with Recyclerviews in them). I created a Tabbed Activity and migrated the code in a new Fragment. When I click on the menuitem with the Tab-Fragment for the first time, it works perfectly fine. But when i browse through the menu and then open the Tab-Fragment again, it shows the 3 Tabs but there's nothing in them. Now when I click on the third Tab, the data is shown. And when I switch back to the first Tab, the Data is back, too. Only the middle Tab stays empty.

I tried this method on a completely new and empty project, only with a navigation drawer activity and an tabbed activity, where I also migrated the code to a fragment. I only used the code which Android-Studio (3.4.2) generated. In these tabs are only textviews, but there's still the same issue.

Tab-Fragment (migrated code from a generated Tabbed Activity):

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

        v = inflater.inflate(R.layout.activity_tab, container, false);

        context = getActivity().getApplicationContext();

        SectionsPagerAdapter sectionsPagerAdapter = new SectionsPagerAdapter(context, getActivity().getSupportFragmentManager());
        ViewPager viewPager = v.findViewById(R.id.view_pager);
        viewPager.setAdapter(sectionsPagerAdapter);
        TabLayout tabs = v.findViewById(R.id.tabs);
        tabs.setupWithViewPager(viewPager);

        return v;
    }

Generated SectionsPagerAdapter:

public class SectionsPagerAdapter extends FragmentPagerAdapter {

    @StringRes
    private static final int[] TAB_TITLES = new int[]{R.string.tab_text_1, R.string.tab_text_2};
    private final Context mContext;

    public SectionsPagerAdapter(Context context, FragmentManager fm) {
        super(fm);
        mContext = context;
    }

    @Override
    public Fragment getItem(int position) {
        // getItem is called to instantiate the fragment for the given page.
        // Return a PlaceholderFragment (defined as a static inner class below).
        return PlaceholderFragment.newInstance(position + 1);
    }

    @Nullable
    @Override
    public CharSequence getPageTitle(int position) {
        return "Some Title";
    }

    @Override
    public int getCount() {
        // Show 3 total pages.
        return 3;
    }
}

I only changed the amount of Tabs in "getCount" and the returned String in "getPageTitle"

I handle the menu item clicks in my Navigation Drawer Activity (Main) with the NavigationItemSelectedListener and change the Fragment like this:

getSupportFragmentManager().beginTransaction().replace(R.id.content, new TabFragment()).commit();

The "activity_tab" layout looks like this:

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.design.widget.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="?attr/colorPrimary" />
    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/view_pager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />
    
</android.support.design.widget.CoordinatorLayout>

Is there a possibility to stay with Fragments on menu item clicks or do I have to use a Tabbed Activity?

Answer 1

First of all, I think you should use childFragmentManager instead of supportFragmentManager.

SectionsPagerAdapter sectionsPagerAdapter = new SectionsPagerAdapter(context, getChildFragmentManager());