Question

This app is a learning exercise for me using fragments, among other things. It has a single activity that manages some different fragments. The first is a ListFragment (A), which shows when the app starts and loads list items from a cursor. Clicking a list item notifies the activity to replace the ListFragment with a DetailFragment (B) for that item. If while looking at (B) I rotate the screen, I see (B) on top of (A), like this:

http://postimage.org/image/uhy016ds7/

My best guess is it has to do with Android destroying and re-creating the activity on a configuration change. I am wondering what is the cleanest solution for this problem. Some code snippets follow, let me know if there’s something else I should post.

res/layout/home.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/fragment_container"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <fragment
        android:id="@+id/fragment_place_list"
        android:name="com.simbiosys.apps.foodfast.ui.PlaceListFragment"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" >
    </fragment>
</FrameLayout>

MyActivity.onCreate

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.home);

    placeListFragment = (PlaceListFragment) getSupportFragmentManager().findFragmentById(
            R.id.fragment_place_list);

}

MyActivity.showDetailPane

public void showDetailPane(String id, String reference) {
    placeDetailFragment = PlaceDetailFragment.newInstance(id, reference);
    FragmentManager fragmentManager = getSupportFragmentManager();
    FragmentTransaction ft = fragmentManager.beginTransaction();
    ft.addToBackStack(null);
    ft.hide(placeListFragment);
    ft.replace(R.id.fragment_container, placeDetailFragment);
    ft.show(placeDetailFragment);
    ft.commit();
}

Answer 1

It is because you use a frame layout as container.
It wouldn’t be overlapping for other layouts.

And for what you want to achieve best practice is to make a XML file into your layout/ folder where only your listfragment is used.
In your layout-land/ you put a XML file with both fragments used and arranged.

Then the system handles all the creation of the. fragments. And your activity basically reduces to a setContentView() call.

On a list item click you then check with the fragment manager whether or not your detail fragment is created. If it is created you your call a public function within the detail fragment to set the data.

If it is not created, you create a intent with a new activity.

I know 2 good tutorials: the fragments page on the android developers page and vogella.de both will give you a detailed example/tutorial.