Develop Reference

Don't reload Fragment's Data after backstack

I have a fragment (MyListFragment) which is a Fragment, i have a list there called myList
this list gets filled with json data onCreateView().
myList -> onItemClick -> open details fragment
after i press the back button the myList list gets reloaded again, i don't want that to happen, instead i want the first fragment to retain the initial state with the loaded data, i used the SlidingPaneLayout for both List/Details fragments, but now i want to use the fragmenttransaction instead cuz i need the SlidingPaneLayout for the menu usage, instead of the list|details slide.
here's a bit of my script
public class MyListFragment extends Fragment {
private AsyncCallBack callback;
public static RelativeLayout loadingListLayout;
public static RelativeLayout listCarsLayout;
public DetailsFragment detailsFragment;
public ArrayList<String> loadedCars = new ArrayList<String>();
public static String loadedCarsString = "";
public static Boolean jsonCarsLoading = false;
public String latestDate;
public static long selectedItem = -1;
public static Boolean isRefreshing = false;
public PullToRefreshListView myList;
public CarsAdapter carsAdapter;
public ArrayList<CarsItems> carsItems;
public ArrayList<CarsItems> results = new ArrayList<CarsItems>();
public static int ON_LOAD_ITEM_COUNT = 20;
public static int ON_REFRESH_ITEM_COUNT = 10;
public static int ON_LOADMORE_ITEM_COUNT = 3;
int currentFirstVisibleItem, currentVisibleItemCount, currentTotalItemCount, currentScrollState;
private View view;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
view = inflater.inflate(R.layout.list_fragment, container, false);
loadingListLayout = (RelativeLayout) view.findViewById(R.id.LoadingListLayout);
listCarsLayout = (RelativeLayout) view.findViewById(R.id.ListLayout);
myList = (PullToRefreshListView) view.findViewById(R.id.CarsList);
detailsFragment = new DetailsFragment();
carsAdapter = new CarsAdapter(getActivity(), results);
myList.setAdapter(carsAdapter);
...
// Get Cars List if online
if (isOnline()) {
Api jsonCars = new Api();
jsonCars.setLimit(ON_LOAD_ITEM_COUNT);
jsonCars.setCallBack(callback);
jsonCars.getLatestItemDate = true;
jsonCars.setExcludeCars(loadedCarsString);
jsonCars.execute("latestCars");
}
i tried to implement the code inside the onAttach(), but whatever i type in there i guet onLaunchActivity error.....

I solved this issue with the help of savedInstanceState()
private Calendar startTime = Calendar.getInstance();
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putSerializable("starttime", startTime);
}
i used to load the dataList inside onCreateView, without any condition, so anyway, when i put this code, and checked back the fragment after pressing the Back button, it seemed that the fragment saved it's instance state, like the position and data, but it kept loading the data (Running the AsyncTask again and again);
so i had to put some conditions:
First
i added this line at the top of my fragment class
public Boolean initialized = false;
to be updated later after first run with 'true';
Second
then added those to the onCreateView() before loading the data
if (initialized == false) {
loadList();
} else {
loadingListLayout.setVisibility(View.GONE);
listLayout.setVisibility(1);
}
the loadingListLayout is just an overlay with a progress bar whilst the data is being loaded
Third
and then inside the loadlist() i added :
public void loadList() {
initialized = true;
...
ran the AsyncTask ...
this way i ensured that the data AsyncTask doesn't get executed everytime i press the backbutton, this way i managed to keep using the the addToBackStack for my fragmentTransaction thing.

i solved it this way, adding those methods to my fragment
public int dismiss() {
try {
if (mBackStackId != -1) {
FragmentManager fm = getFragmentManager();
fm.popBackStack(mBackStackId, FragmentManager.POP_BACK_STACK_INCLUSIVE);
mBackStackId = -1;
FragmentTransaction ft = fm.beginTransaction();
ft.remove(this);
ft.commit();
}
} catch (IllegalArgumentException e) {
return mBackStackId;
}
return mBackStackId;
}
public int show(FragmentManager fm) {
FragmentTransaction ft = fm.beginTransaction();
ft.add(android.R.id.content, this, TAG);
ft.addToBackStack(null);
mBackStackId = ft.commit();
return mBackStackId;
}

ViewPager's Fragment's view lost when ViewPager's parent Fragment hidden then shown

I've been seeing some strange behavior with my ViewPager along with my own FragmentStatePagerAdapter.
My View hierarchy goes like this:
-> (1) Fragment root view (RelativeLayout)
-> (2) ViewPager
-> (3) ViewPager's current fragment view
When the Fragment that is responsible for the Fragment root view (1) gets hidden (using .hide() in a fragment transaction) and then shown (with .show()), the fragment view that was currently showing in the ViewPager (3) becomes null, although the fragment still exists. Basically, my ViewPager becomes completely blank/transparent.
The only way I have found to fix this is to call
int current = myViewPager.getCurrentItem();
myViewPager.setAdapter(myAdapter);
myViewPager.setCurrentItem(current);
after the parent fragment is shown. This somehow triggers the views to be recreated and appear on screen. Unfortunately, this occasionally causes exceptions dealing with the pager adapter calling unregisterDataSetObserver() twice on an old observer.
Is there a better way to do this? I guess what I am asking is:
Why are my fragment views inside my ViewPager getting destroyed when the parent fragment of the ViewPager is hidden?
Update: this also happens when the application is "minimized" and then "restored" (by pressing the home action key and then returning).
Per request, here's my pager adapter class:
public class MyInfoSlidePagerAdapter extends FragmentStatePagerAdapter {
private ArrayList<MyInfo> infos = new ArrayList<MyInfo>();
public MyInfoSlidePagerAdapter (FragmentManager fm) {
super(fm);
}
public MyInfoSlidePagerAdapter (FragmentManager fm, MyInfo[] newInfos) {
super(fm);
setInfos(newInfos);
}
#Override
public int getItemPosition(Object object) {
int position = infos.indexOf(((MyInfoDetailsFragment)object).getMyInfo());
return position > 0 ? position : POSITION_NONE;
}
#Override
public CharSequence getPageTitle(int position) {
return infos.get(position).getName();
}
#Override
public Fragment getItem(int i) {
return infos.size() > 0 ? MyInfoDetailsFragment.getNewInstance(infos.get(i)) : null;
}
#Override
public int getCount() {
return infos.size();
}
public Location getMyInfoAtPosition(int i) {
return infos.get(i);
}
public void setInfos(MyInfo[] newInfos) {
infos = new ArrayList<MyInfo>(Arrays.asList(newInfos));
}
public int getPositionOfMyInfo(MyInfo info) {
return infos.indexOf(info);
}
}
I've renamed some variables but other than that it is exactly what I have.

You're not providing enough info for your specific issue, so I built a sample project that tries to reproduce your issue: the app has an activity that holds a fragment (PagerFragment) within a relative layout and below this layout I have a button that hides & shows above PagerFragment. PagerFragment has a ViewPager and each fragment within pager adapter simply displays a label - this fragment is named DataFragment. The label list is created in parent activity and passed to PagerFragment and then through its adapter to each DataFragment. Changing the PagerFragment visibility is done with no issues and each time it's becoming visible again it shows the previous shown label.
The key of the issue:
Use Fragment#getChildFragmentManager() when you're creating the viewpager adapter and not getFragmentManager!
Maybe you can compare this simple project with what you have and check where are the differences. So here goes (top-down):
PagerActivity (the only activity in the project):
public class PagerActivity extends FragmentActivity {
private static final String PAGER_TAG = "PagerActivity.PAGER_TAG";
#Override
protected void onCreate(Bundle savedInstance) {
super.onCreate(savedInstance);
setContentView(R.layout.pager_activity);
if (savedInstance == null) {
PagerFragment frag = PagerFragment.newInstance(buildPagerData());
FragmentManager fm = getSupportFragmentManager();
fm.beginTransaction().add(R.id.layout_fragments, frag, PAGER_TAG).commit();
}
findViewById(R.id.btnFragments).setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
changeFragmentVisibility();
}
});
}
private List<String> buildPagerData() {
ArrayList<String> pagerData = new ArrayList<String>();
pagerData.add("Robert de Niro");
pagerData.add("John Smith");
pagerData.add("Valerie Irons");
pagerData.add("Metallica");
pagerData.add("Rammstein");
pagerData.add("Zinedine Zidane");
pagerData.add("Ronaldo da Lima");
return pagerData;
}
protected void changeFragmentVisibility() {
Fragment frag = getSupportFragmentManager().findFragmentByTag(PAGER_TAG);
if (frag == null) {
Toast.makeText(this, "No PAGER fragment found", Toast.LENGTH_SHORT).show();
return;
}
boolean visible = frag.isVisible();
Log.d("APSampler", "Pager fragment visibility: " + visible);
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
if (visible) {
ft.hide(frag);
} else {
ft.show(frag);
}
ft.commit();
getSupportFragmentManager().executePendingTransactions();
}
}
its layout file pager_activity.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="4dp" >
<Button
android:id="#+id/btnFragments"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:text="Hide/Show fragments" />
<RelativeLayout
android:id="#+id/layout_fragments"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_above="#+id/btnFragments"
android:layout_marginBottom="4dp" >
</RelativeLayout>
</RelativeLayout>
Observe that I am adding the PagerFragment when the activity is first shown - and the PagerFragment class:
public class PagerFragment extends Fragment {
private static final String DATA_ARGS_KEY = "PagerFragment.DATA_ARGS_KEY";
private List<String> data;
private ViewPager pagerData;
public static PagerFragment newInstance(List<String> data) {
PagerFragment pagerFragment = new PagerFragment();
Bundle args = new Bundle();
ArrayList<String> argsValue = new ArrayList<String>(data);
args.putStringArrayList(DATA_ARGS_KEY, argsValue);
pagerFragment.setArguments(args);
return pagerFragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
data = getArguments().getStringArrayList(DATA_ARGS_KEY);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.pager_fragment, container, false);
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
pagerData = (ViewPager) view.findViewById(R.id.pager_data);
setupPagerData();
}
private void setupPagerData() {
PagerAdapter adapter = new LocalPagerAdapter(getChildFragmentManager(), data);
pagerData.setAdapter(adapter);
}
}
its layout (only the ViewPager that takes full size):
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/pager_data"
android:layout_width="match_parent"
android:layout_height="match_parent" />
and its adapter:
public class LocalPagerAdapter extends FragmentStatePagerAdapter {
private List<String> pagerData;
public LocalPagerAdapter(FragmentManager fm, List<String> pagerData) {
super(fm);
this.pagerData = pagerData;
}
#Override
public Fragment getItem(int position) {
return DataFragment.newInstance(pagerData.get(position));
}
#Override
public int getCount() {
return pagerData.size();
}
}
This adapter creates a DataFragment for each page:
public class DataFragment extends Fragment {
private static final String DATA_ARG_KEY = "DataFragment.DATA_ARG_KEY";
private String localData;
public static DataFragment newInstance(String data) {
DataFragment df = new DataFragment();
Bundle args = new Bundle();
args.putString(DATA_ARG_KEY, data);
df.setArguments(args);
return df;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
localData = getArguments().getString(DATA_ARG_KEY);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.data_fragment, container, false);
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
view.findViewById(R.id.btn_page_action).setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(getActivity(), localData, Toast.LENGTH_SHORT).show();
}
});
((TextView) view.findViewById(R.id.txt_label)).setText(localData);
}
}
and DataFragment's layout:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="4dp" >
<Button
android:id="#+id/btn_page_action"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:text="Interogate" />
<TextView
android:id="#+id/txt_label"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:textAppearance="?android:attr/textAppearanceLarge" />
</RelativeLayout>
Enjoy coding!

maybe it will help mViewPager.setOffscreenPageLimit(5)
Set the number of pages that should be retained to either side of the
current page in the view hierarchy in an idle state. Pages beyond this
limit will be recreated from the adapter when needed.
This is offered as an optimization. If you know in advance the number
of pages you will need to support or have lazy-loading mechanisms in
place on your pages, tweaking this setting can have benefits in
perceived smoothness of paging animations and interaction. If you have
a small number of pages (3-4) that you can keep active all at once,
less time will be spent in layout for newly created view subtrees as
the user pages back and forth.
You should keep this limit low, especially if your pages have complex
layouts. This setting defaults to 1.

View Pager is pretty adamant in keeping keeping its Fragments fresh always and thus optimizing the performance by freeing up memory when a fragment is not used. Clearly that is a valid useful trait in a mobile system. But due to this persistent deallocation of resources the fragment is created everytime it gains focus.
mViewPager.setOffscreenPageLimit(NUMBEROFFRAGMENTSCREENS);
Here is the documentation.
this Old Post has an interesting Solution for your problem.. Please Refer

For me i changed to getChildFragmentManager() instead of getFragmentManager()
and works good.
Ex:
pagerAdapt = new PagerAdapt(getChildFragmentManager());

I had the same problem. My app (FragmentActivity) has a pager (ViewPager) with 3 framgents. While swiping between the fragments they are destroyed and recreated all the time. Actually it makes no problem in functionality (expect unclosed Cursors), but I was also wondering about this question.
I do not know if there is a workaround to change the behavior of the ViewPager, but I suggest to have a configuration object (maybe a static on) and before destroy save your myViewPager object at the config object.
public class App extends FragmentActivity {
static MyData data;
#Override
protected void onCreate(Bundle savedInstanceState) {
data = (MyData) getLastCustomNonConfigurationInstance();
if (data == null) {
data = new MyData();
data.savedViewPager = myViewPager;
} else {
myViewPager = data.savedViewPager;
}
}
#Override
public Object onRetainCustomNonConfigurationInstance() {
Log.d("onRetainCustomNonConfigurationInstance", "Configuration call");
return data;
}
}
public class MyData {
public ViewPager savedViewPager;
}
With this way, you can save the reference to the an object which won't be destroyed hence there is reference to it and you can reload all your crucial objects.
I hope you find my suggestion useful!

Fragment in ViewPager not restored after popBackStack

Problem
A Fragment is not reattached to its hosting ViewPager after returning from another fragment.
Situation
One Activity hosting a Fragment whose layout holds a ViewPager (PageListFragment in the example below). The ViewPager is populated by a FragmentStateViewPagerAdapter. The single Fragments hosted inside the pager (PageFragment in the example below) can open sub page lists, containing a new set of pages.
Behaviour
All works fine as long as the back button is not pressed. As soon as the user closes one of the sub PageLists the previous List is recreated, but without the Page that was displayed previously. Swiping through the other pages on the parent PageList still works.
Code
A sample application can be found on github:
Activity
public class MainActivity extends FragmentActivity {
private static final String CURRENT_FRAGMENT = MainActivity.class.getCanonicalName() + ".CURRENT_FRAGMENT";
public static final String ARG_PARENTS = "Parents";
public void goInto(String mHostingLevel, String mPosition) {
Fragment hostingFragment = newHostingFragment(mHostingLevel, mPosition);
addFragment(hostingFragment);
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
addBaseFragment();
}
private void addBaseFragment() {
Fragment hostingFragment = newHostingFragment("", "");
addFragment(hostingFragment);
}
private Fragment newHostingFragment(String mHostingLevel, String oldPosition) {
Fragment hostingFragment = new PageListFragment();
Bundle args = new Bundle();
args.putString(ARG_PARENTS, mHostingLevel + oldPosition +" > ");
hostingFragment.setArguments(args);
return hostingFragment;
}
private void addFragment(Fragment hostingFragment) {
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragmentSpace, hostingFragment, CURRENT_FRAGMENT);
transaction.addToBackStack(null);
transaction.commit();
}
}
PageListFragment
public class PageListFragment extends Fragment {
private String mParentString;
public PageListFragment() {
// Required empty public constructor
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_hosting, container, false);
}
#Override
public void onResume() {
mParentString = getArguments().getString(MainActivity.ARG_PARENTS);
ViewPager viewPager = (ViewPager) getView().findViewById(R.id.viewPager);
viewPager.setAdapter(new SimpleFragmentStatePagerAdapter(getFragmentManager(),mParentString));
super.onResume();
}
private static class SimpleFragmentStatePagerAdapter extends FragmentStatePagerAdapter {
private String mHostingLevel;
public SimpleFragmentStatePagerAdapter(FragmentManager fm, String hostingLevel) {
super(fm);
this.mHostingLevel = hostingLevel;
}
#Override
public android.support.v4.app.Fragment getItem(int position) {
PageFragment pageFragment = new PageFragment();
Bundle args = new Bundle();
args.putString(MainActivity.ARG_PARENTS, mHostingLevel);
args.putInt(PageFragment.ARG_POSITION, position);
pageFragment.setArguments(args);
return pageFragment;
}
#Override
public int getCount() {
return 5;
}
}
}
PageFragment
public class PageFragment extends Fragment {
public static final String ARG_POSITION = "Position";
private String mHostingLevel;
private int mPosition;
public PageFragment() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View contentView = inflater.inflate(R.layout.fragment_page, container, false);
setupTextView(contentView);
setupButton(contentView);
return contentView;
}
private void setupTextView(View contentView) {
mPosition = getArguments().getInt(ARG_POSITION);
mHostingLevel = getArguments().getString(MainActivity.ARG_PARENTS);
TextView text = (TextView) contentView.findViewById(R.id.textView);
text.setText("Parent Fragments " + mHostingLevel + " \n\nCurrent Fragment "+ mPosition);
}
private void setupButton(View contentView) {
Button button = (Button) contentView.findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
openNewLevel();
}
});
}
protected void openNewLevel() {
MainActivity activity = (MainActivity) getActivity();
activity.goInto(mHostingLevel, Integer.toString(mPosition));
}
}

After a lengthy investigation it turns out to be a problem with the fragment manager.
When using a construct like the one above the fragment transaction to reattach the fragment to the page list is silently discarded. It is basically the same problem that causes a
java.lang.IllegalStateException: Recursive entry to executePendingTransactions
when trying to alter the fragments inside the FragmentPager.
The same solution, as for problems with this error, is also applicable here. When constructing the FragmentStatePagerAdapter supply the correct child fragment manager.
Instead of
viewPager.setAdapter(new SimpleFragmentStatePagerAdapter(getFragmentManager(),mParentString));
do
viewPager.setAdapter(new SimpleFragmentStatePagerAdapter(getChildFragmentManager(),mParentString));
See also: github

What Paul has failed to mention is, if you use getChildFragmentManager, then you will suffer the "blank screen on back pressed" issue.

The hierarchy in my case was:
MainActivity->MainFragment->TabLayout+ViewPager->AccountsFragment+SavingsFragment+InvestmentsFragment etc.
The problem I had was that I couldn't use childFragmentManagerfor the reason that a click on the item Account view (who resides inside one of the Fragments of the ViewPager) needed to replace MainFragment i.e. the entire screen.
Using MainFragments host Fragment i.e. passing getFragmentManager() enabled the replacing, BUT when popping the back-stack, I ended up with this screen:
This was apparent also by looking at the layout inspector where the ViewPager is empty.
Apparently looking at the restored Fragments you would notice that their View is restored but will not match the hierarchy of the popped state. In order to make the minimum impact and not force a re-creation of the Fragments I re-wrote FragmentStatePagerAdapter with the following changes:
I copied the entire code of FragmentStatePagerAdapter and changed
#NonNull
#Override
public Object instantiateItem(#NonNull ViewGroup container, int position) {
// If we already have this item instantiated, there is nothing
// to do. This can happen when we are restoring the entire pager
// from its saved state, where the fragment manager has already
// taken care of restoring the fragments we previously had instantiated.
if (mFragments.size() > position) {
Fragment f = mFragments.get(position);
if (f != null) {
return f;
}
}
...
}
with
#NonNull
#Override
public Object instantiateItem(#NonNull ViewGroup container, int position) {
// If we already have this item instantiated, there is nothing
// to do. This can happen when we are restoring the entire pager
// from its saved state, where the fragment manager has already
// taken care of restoring the fragments we previously had instantiated.
if (mFragments.size() > position) {
Fragment f = mFragments.get(position);
if (f != null) {
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
mCurTransaction.detach(f);
mCurTransaction.attach(f);
return f;
}
}
...
}
This way I am effectively making sure that that the restored Fragments are re-attached to the ViewPager.

Delete all page fragments, enabling them to be re-added later
The page fragments are not attached when you return to the viewpager screen as the FragmentStatePagerAdapter is not re-connecting them. As a work-around, delete all the fragments in the viewpager after popbackstack() is called, which will allow them to be re-added by your initial code.
[This example is written in Kotlin]
//Clear all fragments from the adapter before they are re-added.
for (i: Int in 0 until adapter.count) {
val item = childFragmentManager.findFragmentByTag("f$i")
if (item != null) {
adapter.destroyItem(container!!, i, item)
}
}

Fool-proof way to handle Fragment on orientation change

public class MainActivity extends Activity implements MainMenuFragment.OnMainMenuItemSelectedListener {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager
.beginTransaction();
// add menu fragment
MainMenuFragment myFragment = new MainMenuFragment();
fragmentTransaction.add(R.id.menu_fragment, myFragment);
//add content
DetailPart1 content1= new DetailPart1 ();
fragmentTransaction.add(R.id.content_fragment, content1);
fragmentTransaction.commit();
}
public void onMainMenuSelected(String tag) {
//next menu is selected replace existing fragment
}
I have a need to display two list views side by side, menu on left and its content on right side. By default, the first menu is selected and its content is displayed on right side. The Fragment that displays content is as below:
public class DetailPart1 extends Fragment {
ArrayList<HashMap<String, String>> myList = new ArrayList<HashMap<String, String>>();
ListAdapter adap;
ListView listview;
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
if(savedInstanceState!=null){
myList = (ArrayList)savedInstanceState.getSerializable("MYLIST_obj");
adap = new LoadImageFromArrayListAdapter(getActivity(),myList );
listview.setAdapter(adap);
}else{
//get list and load in list view
getlistTask = new GetALLListTasks().execute();
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.skyview_fragment, container,false);
return v;
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putSerializable("MYLIST_obj", myList );
}
}
The onActivityCreated and onCreateView are called twice. There are many examples out there using fragments. Since I am beginner in this subject, I am unable relate the example with my problem. I need a fool proof way to handle orientation change. I have NOT declared android:configChanges in manifest file. I need the activity destroy and recreate so that I can use different layout in landscape mode.

You are creating a new fragment every time you turn the screen in your activity onCreate(); But you are also maintaining the old ones with super.onCreate(savedInstanceState);. So maybe set tag and find the fragment if it exists, or pass null bundle to super.
This took me a while to learn and it can really be a pain when you are working with stuff like viewpager.
I'd recommend you to read about fragments an extra time as this exact topic is covered.
Here is an example of how to handle fragments on a regular orientation change:
Activity:
public class MainActivity extends FragmentActivity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
TestFragment test = new TestFragment();
test.setArguments(getIntent().getExtras());
getSupportFragmentManager().beginTransaction().replace(android.R.id.content, test, "your_fragment_tag").commit();
} else {
TestFragment test = (TestFragment) getSupportFragmentManager().findFragmentByTag("your_fragment_tag");
}
}
}
Fragment:
public class TestFragment extends Fragment {
public static final String KEY_ITEM = "unique_key";
public static final String KEY_INDEX = "index_key";
private String mTime;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_layout, container, false);
if (savedInstanceState != null) {
// Restore last state
mTime = savedInstanceState.getString("time_key");
} else {
mTime = "" + Calendar.getInstance().getTimeInMillis();
}
TextView title = (TextView) view.findViewById(R.id.fragment_test);
title.setText(mTime);
return view;
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putString("time_key", mTime);
}
}

A good guideline about how to retain data between orientation changes and activity recreation can be found in android guidelines.
Summary:
make your fragment retainable:
setRetainInstance(true);
Create a new fragment only if necessary (or at least take data from it)
dataFragment = (DataFragment) fm.findFragmentByTag("data");
// create the fragment and data the first time
if (dataFragment == null) {

Updating content within fragment

I am working on an android project and I am trying to work out how I can use fragments to make a tablet friendly UI for my app. But I am unsure how to update fragment B depending on what happens in fragment A. I know I need some sort of interface but I can't work out how to implement it.
Basically, what I have is an activity called MainActivity which sets the layout for the fragments.
In landscape mode the XML file is.
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent">
<fragment android:name="com.BoardiesITSolutions.FragmentTest.FragmentA"
android:id="#+id/list"
android:layout_weight="1"
android:layout_width="0px"
android:layout_height="match_parent">
</fragment>
<FrameLayout android:id="#+id/viewer"
android:layout_weight="1"
android:layout_width="0px"
android:layout_height="match_parent"
android:background="?android:attr/detailsElementBackground">
</FrameLayout>
</LinearLayout>
In portrait mode its
Currently the MainActivity just sets the content view to the XML file above using SetContentView within in the onCreate method. Below is how it looks.
In the FragmentA class file it extends ListFragment and contains a ListView of items and what I want to be able to do is to update the textview within Fragment B based on what is selected in Fragment A.
Below is the code for fragment A.
#Override
public View onCreateView(LayoutInflater inflator, ViewGroup container, Bundle savedInstanceState)
{
return inflator.inflate(R.layout.fragment_a, container, false);
}
#Override
public void onActivityCreated(Bundle savedInstanceState)
{
super.onActivityCreated(savedInstanceState);
myListView = getListView();
ArrayList<String> arrayList = new ArrayList<String>();
arrayList.add("Item1");
arrayList.add("Item2");
arrayList.add("Item3");
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(getActivity().getApplicationContext(),
android.R.layout.simple_list_item_activated_1, arrayList);
setListAdapter(arrayAdapter);
View fragmentB = getActivity().findViewById(R.id.viewer);
mDualPane = fragmentB != null && fragmentB.getVisibility() == View.VISIBLE;
if (savedInstanceState != null)
{
mCurCheckPosition = savedInstanceState.getInt("curChoice", 0);
}
if (mDualPane)
{
myListView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
showDetails(mCurCheckPosition);
}
}
#Override
public void onListItemClick(ListView l, View view, int position, long id)
{
showDetails(position);
}
private void showDetails(int index)
{
mCurCheckPosition = index;
if (mDualPane)
{
myListView.setItemChecked(index, true);
FragmentB details = (FragmentB)getFragmentManager().findFragmentById(R.id.viewer);
if (details == null || details.getShownIndex() != index)
{
details = FragmentB.newInstance(index);
FragmentTransaction fragmentTransaction = getFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.viewer, details);
fragmentTransaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
fragmentTransaction.commit();
}
}
else
{
Intent intent = new Intent(getActivity(), FragmentBActivity.class);
intent.putExtra("index", index);
startActivity(intent);
}
}
#Override
public void onSaveInstanceState(Bundle outState)
{
super.onSaveInstanceState(outState);
outState.putInt("curChoice", mCurCheckPosition);
}
FragmentB contains the following code, this class extends Fragment
public View onCreateView(LayoutInflater inflator, ViewGroup container, Bundle savedInstanceState)
{
if (container == null)
{
return null;
}
View view = inflator.inflate(R.layout.fragment_b, container, false);
return view;
}
public static FragmentB newInstance(int index)
{
FragmentB fragmentB = new FragmentB();
Bundle args = new Bundle();
args.putInt("index", index);
//rgs.putString("content", content);
fragmentB.setArguments(args);
return fragmentB;
}
public int getShownIndex()
{
return getArguments().getInt("index", 0);
}
And in the Activity file for FragmentB it contains the following
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
if (getResources().getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE)
{
finish();
return;
}
if (savedInstanceState == null)
{
FragmentB fragmentB = new FragmentB();
fragmentB.setArguments(getIntent().getExtras());
getFragmentManager().beginTransaction().add(android.R.id.content, fragmentB).commit();
}
}
As you can see from the screenshot above, I have the basis of the fragments working and when I click on each item, it shows what the currently selected item is, but I have no idea how to tell it to update the textview in fragment b based on what the user clicked from fragment a and how this is handled in both portrait and landscape mode.
Thanks for any help you can provide.

You may override the onActivityCreated() method of FragmentB, find view by id of that TextView, and update it.
Here's a mock:
public class FragmentB extends Fragment{
//......
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
TextView textView = getActivity().findViewById(R.id.my_textview);
textView.setText("Hello World!");
}
}

but I have no idea how to tell it to update the textview in fragment b based on what the user clicked from fragment a and how this is handled in both portrait and landscape mode.
Have Fragment A call a method on the hosting activity to let it know that the user clicked on something. The hosting activity can then either call a method on Fragment B (if that fragment exists), or start up Fragment B (if the fragment does not exist but there is room for it), or start an activity that will be responsible for displaying Fragment B (e.g., on a phone).
What I wouldn't do is what you are doing: having Fragment A create Fragment B. Fragment A should not care if Fragment B exists or not; that is the activity's job. Fragment A should only worry about Fragment A, plus passing necessary events to the activity.