Handle fragmentation fragmentation during screen rotation (with sample code)

There are several similar answers, but not in this situation.

My situation is simple.

I have an Activity with two different layouts, one in Portrait, the other in Landscape.

In Portrait , I use <FrameLayout>and add Fragmentto it dynamically .

In Landscape, I use <fragment>, therefore, Fragment static . (it doesn't really matter)

First it starts with Portrait , then I added Fragmentsimply:

ListFrag listFrag = new ListFrag();
getSupportFragmentManager().beginTransaction()
        .replace(R.id.FragmentContainer, listFrag).commit();

where ListFrag extends ListFragment.

Then I rotate the screen. I found that listFrag is recreated in landscape mode. (In which I noticed that the method is onCreate()again called with a non-zero package)

I tried using setRetainInstance(false), like @NPike, in this post . But getRetainInstance()already falseby default. He does not do what I expected from. Can anyone explain this?

The snippet I'm dealing with is the ListFragmentone that does setListAdapter()at onCreate(). Therefore, the method cannot be used here. (or I don’t know how to apply). if (container == null) return null;

. if (bundle != null) setListAdapter(null); else setListAdapter(new ...); ListFragment? / , /, ? ( if (container == null) return null;)

Edit:

, , getSupportFragmentManager().beginTransaction().remove(getSupportFragmentManager().findFragmentById(R.id.FragmentContainer)).commit(); onSaveInstanceState(). .

• , , WhatsApp TXT, . ( , ).

• , . onCreate(Bundle) onRestoreInstanceState(Bundle). (1), onCreate(Bundle) onRestoreInstanceState(Bundle) , . Activity ( Bundle).

, , , getSupportFragmentManager()...replace(...).commit(); Portrait.

, :)

MainActivity.java

package com.example.fragremovetrial;

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

public class MainActivity extends FragmentActivity {

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

        if (findViewById(R.id.FragmentContainer) != null) {
            System.out.println("-- Portrait --");       // Portrait
            ListFrag listFrag = new ListFrag();
            getSupportFragmentManager().beginTransaction()
                    .replace(R.id.FragmentContainer, listFrag).commit();
        } else {
            System.out.println("-- Landscape --");      // Landscape
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        if (findViewById(R.id.FragmentContainer) != null) {
            System.out.println("getRetainInstance = " +
                    getSupportFragmentManager().findFragmentById(R.id.FragmentContainer).getRetainInstance());
        }
    }
}

/activity _main.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/FragmentContainer"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" />

layout-land/activity_main.xml ( )

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
</LinearLayout>

ListFrag.java

package com.example.fragremovetrial;

import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.widget.ArrayAdapter;

public class ListFrag extends ListFragment {
    private String[] MenuItems = { "Content A", "Contnet B" };

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

        System.out.println("ListFrag.onCreate(): " + (savedInstanceState == null ? null : savedInstanceState));

        setListAdapter(new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, MenuItems));
    }
}

,

- -
ListFrag.onCreate(): null
getRetainInstance = false

( → )

ListFrag.onCreate(): Bundle [{android: view_state=android.util.SparseArray@4052dd28}]
- -
id 16908298 , .

( → )

ListFrag.onCreate(): Bundle [{android: view_state=android.util.SparseArray@405166c8}]
- -
ListFrag.onCreate(): null
getRetainInstance = false

( → )

ListFrag.onCreate(): Bundle [{android: view_state=android.util.SparseArray@4050fb40}]
- -
id 16908298 , .

( → )

ListFrag.onCreate(): Bundle [{android: view_state=android.util.SparseArray@40528c60}]
- -
ListFrag.onCreate(): null
getRetainInstance = false

, , . (, )