Fragments Detatch/Reattach Vs Show/Hide

Question

I am having trouble figuring out the proper way to navigate through fragments without a pager and i am having problems during Configuration changes for screen orientation. I am using Show/Hide on the fragments to make them visible and functional but i am wondering if i should instead be using Detach/Attach. I am also having problems adding things to the back stack and i think it is also due to the use of show/hide. Is it better to use Attach/detatch or is there a way to override what the back button does to make it show/hide the last/current fragment.

The Behavior: I have a map fragment and a List fragment along with a few others. everything starts up correctly and works initially with orientation changes. When i navigate to the list view it populates correctly but upon orientation change the list gets redrawn without the Data in it. The map view also gets redrawn and is visible behind my pager title indicator. If anyone could please point me in right direction for solving this that would be awesome. I am suspecting that is is caused by the way that i am showing and hiding the fragments.

Here is where i create the Fragments and add them to the fragment manager. I have also shown where i show/hide fragments.

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_map_frags);
    mapViewContainer = LayoutInflater.from(this)
            .inflate(R.layout.map, null);

    setupFragments();
    showFragment(0);
}
public void setListData(String name) {
    bName = name;
    showFragment(1);
}
private void setupFragments() {
    final FragmentManager fm = getSupportFragmentManager();
    final FragmentTransaction ft = fm.beginTransaction();
    mFragment1 = fm.findFragmentByTag("f1");
    if (mFragment1 == null) {
        mFragment1 = new MenuFragment();
        ft.add(mFragment1, "f1");
        ft.hide(mFragment1);
    }
    mMapFragment = (MapFragment) getSupportFragmentManager()
            .findFragmentByTag(MapFragment.TAG);
    if (mMapFragment == null) {
        mMapFragment = MapFragment.newInstance(0);
        ft.add(R.id.fragment_container, mMapFragment, MapFragment.TAG);
    }
    ft.hide(mMapFragment);

    myListFragment = (ListFrag) getSupportFragmentManager()
            .findFragmentByTag(ListFrag.TAG);
    if (myListFragment == null) {
        myListFragment = new ListFrag();
        ft.add(R.id.fragment_container, myListFragment, ListFrag.TAG);
    }
    ft.hide(myListFragment);

    frag = (frag) getSupportFragmentManager().findFragmentByTag(
            frag.TAG);
    if (frag == null) {
        bacFrag = new frag();
        ft.add(R.id.fragment_container, frag, frag.TAG);
    }
    ft.hide(bacFrag);
    ft.commit();
}

public void showFragment(int fragIn) {
    final FragmentTransaction ft = getSupportFragmentManager()
            .beginTransaction();
    ft.setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_out);
    if (mVisible != null) {
        if (mVisible == mListFragment) {
            ft.remove(mListFragment);
        } else {
            ft.hide(mVisible);
        } 
    }

    switch (fragIn) {
    case 0:
        ft.show(mMapFragment);
        ft.commit();
        mVisible = mMapFragment;
        break;
    case 1:
        mListFragment = (ListFragmentDisplay) getSupportFragmentManager()
                .findFragmentByTag(ListFragmentDisplay.TAG);
        Toast.makeText(this, "startListFrag", Toast.LENGTH_LONG).show();
        if (mListFragment == null) {
            mListFragment = new ListFragmentDisplay();
            ft.add(R.id.fragment_container, mListFragment,
                    ListFragmentDisplay.TAG);
        }
        ft.show(mListFragment).commit();
        mVisible = mListFragment;
        break;
    case 2:
        ft.show(myfragment).commit();
        mVisible = myfragment;
        break;
    case 3:
        ft.show(frag).commit();
        mVisible = frag;
        break;
    }
}

if you want to stop your activity from restarting on orientation change you may add android:configChanges="orientation|keyboardHidden" in the manifest. — Faizan, Dec 08 '12 at 01:41
Detach/Attach will free up the resources, while hide/show won't. — Faizan, Dec 08 '12 at 01:42

score 4 · Accepted Answer · edited Jun 18 '13 at 04:30

4

It's not your fault. The problem is that when the orientation changes all the Activity is Destroyed, even all the fragments added. So none of the data within it is retained. It's not advised to use android:configChanges="orientation|keyboardHidden". Rather, set for every fragment setRetainInstance(true) and it will work well with your current code.

edited Jun 18 '13 at 04:30

Lalit Poptani

67,150
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answered Feb 15 '13 at 13:53

lorenzop

525
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19

This does not work for multiple fragments on a single screen. But it would have solved my problem above had i not given up and remade everything another way. – doubleA Jul 01 '13 at 08:14
This is not actually answering the question in the title. – stdout Oct 24 '16 at 11:36

score 0 · Answer 2 · answered Jun 18 '13 at 04:09

If you want to have a better persistence (for example when the activity is temporarily destroyed for space issues) also remember to save the state of your fragments with onSaveInstanceState. setRetainInstance will work only when a configuration change is about to come.

Fragments Detatch/Reattach Vs Show/Hide

2 Answers2