I'm using loader in my ListView fragment, and it's getting recreated on pressing "back" button. Can you tell me how to handle this senario?
Here is my ListView fragment code. Here I have a boolean variable that I'm setting as true on clicking on list item. but once the back button is pressed onCreateView will get called so the backbutton will be false.
public class GTFragment extends SherlockFragment implements LoaderCallbacks<Cursor>{
ListView mTListview = null;
GoogleTasksAdapter mGTasksAdapter = null;
private SQLiteCursorLoader mTLoader=null;
private LoaderManager mTLoaderManager;
private String mSelectedListID = null;
private boolean mIsBackbuttonisPressed = false;
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.task_home_activity, container, false);
if(!mIsBackbuttonisPressed)
getLoaderManager().initLoader(0, null, this);
mTListview = (ListView) view.findViewById(R.id.id_task_list_home_activity);
mGTasksAdapter = new GoogleTasksAdapter(getActivity());
mTListview.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> listview,
View clickedview, int position, long arg3) {
// TODO Auto-generated method stub
GoogleTaskItem item = new GoogleTaskItem();
Cursor coursor = ((GoogleTasksAdapter)listview.getAdapter()).getCursor();
if(coursor.moveToPosition(position))
{
mIsBackbuttonisPressed = true;
GoogleTaskController.get_googletask_controllerObj()
.LaunchTaskPreviewActivity();
}
}
});
mTListview.setAdapter(mGTasksAdapter);
mIsBackbuttonisPressed = false;
return view;
}
My fragment activity class code
public class TLActivity extends SherlockFragmentActivity {
LeftSliderTaskListOptions mTaskOptionsFragment = null;
GoogleTasksFragment mTFragment = null;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
setContentView(R.layout.layout_gt_list);
// FragmentTransaction tfragment = this.getSupportFragmentManager().beginTransaction();
mTFragment = new GTasksFragment();
t.replace(R.id.id_tfragment, mTFragment);
t.commit();
}
instead of
t.replace(R.id.id_tfragment, mTFragment);
use
t.add(R.id.id_tfragment, mTFragment);
It worked for me
I don't think that the accepted answer is right because Fragment.onSaveInstanceState will not be called until the activity hosting it needs to save its state: The docs states:
There are many situations where a fragment may be mostly torn down
(such as when placed on the back stack with no UI showing), but its
state will not be saved until its owning activity actually needs to
save its state.
In other words: if you're using a Activity with multiple fragments for each screen (which is very common), the fragment state will not be saved when you move the next screen.
You also can't use Fragment.setRetainInstance because he's meant only to fragments that aren't on the back stack.
Most of the time, you don't have to think about this but sometimes it's important. Like when you have scrolled a list and want to "remember" the scroll location.
I took a long time to realize that the fragments put on the back stack are kind of saved and you can reuse the view that you already created instead of creating one every time the fragment calls onCreateView. My setup is something like this:
public abstract class BaseFragment extends Fragment {
private boolean mSaveView = false;
private SoftReference<View> mViewReference;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
if (mSaveView) {
if (mViewReference != null) {
final View savedView = mViewReference.get();
if (savedView != null) {
if (savedView.getParent() != null) {
((ViewGroup) savedView.getParent()).removeView(savedView);
return savedView;
}
}
}
}
final View view = inflater.inflate(getFragmentResource(), container, false);
mViewReference = new SoftReference<View>(view);
return view;
}
protected void setSaveView(boolean value) {
mSaveView = value;
}
}
public class MyFragment extends BaseFragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
setSaveView(true);
final View view = super.onCreateView(inflater, container, savedInstanceState);
ListView placesList = (ListView) view.findViewById(R.id.places_list);
if (placesList.getAdapter() == null) { // this check is important so you don't restart your adapter
placesList.setAdapter(createAdapter());
}
}
}
You have multiple options to rectify this issue.
Override onSaveInstanceState like this:
#Override
public void onSaveInstanceState (Bundle outState) {
super.onSaveInstanceState(outState);
outState.putBoolean("mIsBackbuttonisPressed", mIsBackbuttonisPressed);
}
and then in your onCreateView you can get your variable back by:
if (savedInstanceState != null)
mIsBackbuttonisPressed = savedInstanceState.getBoolean("mIsBackbuttonisPressed", false);
You can set this.setRetainInstance(true); in your onCreate method of your fragment.
If you could post your Activity code with creates your fragment I can also tell you other options. (P.S I cannot write it as a comment so posting it in the answer.)
Related
I created a tabbed app where the main acitvity contains two layouts. The top layout contains the actual tabbar (which is a fragment). Underneth the content layout contains another fragments depending on which tabbar button the user has clicked. In order to stay compatible with older android versions I use android.support.v4.app.Fragment.
So, in the tabbar menu I added two buttons and each button triggers another fragment in the content. This is what the code looks like:
public class TabbarMenuFragment extends Fragment implements View.OnClickListener {
LiveFragment liveFragment;
OddsFragment oddsFragment;
FragmentTransaction fragmentTransaction;
Button liveButton;
Button oddsButton;
public TabbarMenuFragment() {}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
liveFragment = new LiveFragment();
oddsFragment = new OddsFragment();
fragmentTransaction = getFragmentManager().beginTransaction().add(R.id.content_view, oddsFragment);
fragmentTransaction.commit();
View rootView = (View) inflater.inflate(R.layout.tabbar_menu, container, false);
liveButton = (Button) rootView.findViewById(R.id.liveButton);
liveButton.setOnClickListener(this);
oddsButton = (Button) rootView.findViewById(R.id.oddsButton);
oddsButton.setOnClickListener(this);
return rootView;
}
public void updateUIInTabs() {
liveFragment.updateUI();
}
#Override
public void onClick(View v) {
if(v == liveButton) {
fragmentTransaction = getFragmentManager().beginTransaction().replace(R.id.content_view, liveFragment);
fragmentTransaction.commit();
}
if(v == oddsButton) {
fragmentTransaction = getFragmentManager().beginTransaction().replace(R.id.content_view, oddsFragment);
fragmentTransaction.commit();
}
updateUIInTabs();
}
}
The important thing is that the liveFragment is a Fragment that contains a ListView:
public class LiveFragment extends Fragment {
LiveMainAdapter adapter;
ListView list;
LayoutInflater inflater;
View rootView;
public LiveFragment() {}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
this.inflater = inflater;
rootView = (View) inflater.inflate(R.layout.live_fragment, container, false);
adapter = new LiveMainAdapter(inflater);
list = (ListView) rootView.findViewById(R.id.live_fragment_ListView);
list.setAdapter(adapter);
list.setDivider(null);
list.setDividerHeight(0);
return rootView;
}
public void updateUI() {
if(list != null) {
list.invalidate();
adapter.createRowObjects();
adapter.notifyDataSetChanged();
}
}
}
The oddsFragment is so far just a dummy with a TextView:
public class OddsFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = (View) inflater.inflate(R.layout.odds_fragment, container, false);
return rootView;
}
}
Now there are two settings which are important:
First:
As described above: I start the app and the oddsFragment is initally shown. Now, when I click on the liveFragment button the liveFragment's ListView is not updated.
Clicking again on the button for oddsFragment the oddsFragment is properly shown. Clicking back to liveFragment I get nothing - no ListView is shown.
The second setting:
Is exactly the same as the first, but instead I set the liveFragment as the intial view that is in TabbarMenuFragment I replace:
fragmentTransaction = getFragmentManager().beginTransaction().add(R.id.content_view, oddsFragment);
with
fragmentTransaction = getFragmentManager().beginTransaction().add(R.id.content_view, liveFragment);
Then the ListView is properly shown and the data in the list view is updated and displayed correctly. However, if I click on oddsFragement and then again on liveFragement the ListView has disappeared.
I already tried different things for over two hours now and I'm pretty desperated because I have not clue what might be the reason for this wired behaviour.
Anybody got an idea what is going on here?
Give this a try...
In your LiveFragment add a Handler and a Runnable and update the UI from your Runnable.
Handler handler = new Handler();
Runnable updater = new Runnable()
{
public void run()
{
if(list != null) {
list.invalidate();
adapter.createRowObjects();
adapter.notifyDataSetChanged();
}
}
};
and then change your updateUI() method in LiveFragment
public void updateUI()
{
handler.post(updater);
}
I have the following fragment as below, wherein the onPostNetworkRequestWithCode() method is called back by another part of the code (the App extends Application class which does network requests), to paint the views
Since the fragment creation chain (onCreate(), onCreateView() etc) are called in a different thread than the onPostNetworkRequestWithCode() which repaints the views, I am having a race condition sometimes when the onPostNetworkRequestWithCode() method does not find a view to paint. How can I ask it to wait till the view creation is done and then resume post that?
public class MeStatsTableFragment extends Fragment implements HttpResponseHandlerWithResponseCode {
private static final String LINKED_USER_ID = "linkedUserId";
private Context mContext;
public MeStatsTableFragment() {
// Required empty public constructor
}
public static MeStatsTableFragment newInstance(long linkedUserId, Context context) {
MeStatsTableFragment fragment = new MeStatsTableFragment();
Bundle args = new Bundle();
args.putLong(LINKED_USER_ID, linkedUserId);
fragment.setArguments(args);
fragment.mContext = context;
return fragment;
}
/**
* This is responsible for painting the chart after data is obtained by parent Me Fragment
*/
#Override
public void onPostNetworkRequestWithCode(HttpResponseCode responseCode) {
long linkedUserId = getArguments().getLong(LINKED_USER_ID);
MePageInfo m = App.getAppData().getMePageInfoById(linkedUserId);
View v = getView();
if (v == null) {
Log.d("XXX", "Stats fragment Got stuck at view == null in Stats Fragment");
// do nothing else, just return
} else{
v.findViewById(R.id.text_name).setText(m.name);
// do other painting similarly with the view and the variable m
}
#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
View v = inflater.inflate(R.layout.fragment_me_stats_table, container, false);
return v;
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
}
}
You could use greenrobot EventBus (https://github.com/greenrobot/EventBus) - and make a sticky post, in a case when there is no fragment yet.
Here is more info about sticky post and register - https://github.com/greenrobot/EventBus/blob/master/HOWTO.md#sticky-events
I have seen Link1 for this issue but could understand it right. I have a fragment that loads a list. When i click the list item it opens another activity. But i press back button it loads the list again. I want it to be at the same scroll position where it was before. In above mentioned link it specifies to use flag but i haven't got the point.
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_dashboard);
android.app.Fragment fragment = new MeFragment();
getFragmentManager().beginTransaction().replace(R.id.layout_FragmentsContainer, fragment).addToBackStack(null).commit();
}
}
public class MeFragment extends Fragment
{
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
return inflater.inflate(R.layout.fragment_me, container, false);
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
meLV = (ListView) getView().findViewById(R.id.lv_Inbox);
loadingListProgress = (ProgressBar) getView().findViewById(R.id.progress_LoadingList);
meList = new ArrayList<Message>();
meAdapter = new MessagesListAdapter(getActivity(), meList);
//addFooter();
meLV.setAdapter(meAdapter);
meLV.setOnItemClickListener(this);
pageCount = 0;
loadmoreProgressDialog = new ProgressDialog(getActivity());
loadmoreProgressDialog.setTitle("Please wait ...");
loadmoreProgressDialog.setMessage("Loading more ...");
loadmoreProgressDialog.setCancelable(true);
loadUserMessages();
meLV.setOnScrollListener(new EndlessScrollListener() {
#Override
public void onLoadMore(int page, int totalItemsCount) {
// TODO Auto-generated method stub
//addFooter();
loadmoreProgressDialog.show();
loadUserMessages();
}
});
}
#Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
// TODO Auto-generated method stub
Utils.showToast_msg(getActivity(), "MessageItemClicked");
ReferralDetailFragment fragment = new ReferralDetailFragment();
getFragmentManager().beginTransaction().replace(R.id.layout_FragmentsContainer, fragment).addToBackStack(null).commit();
}
}
public class ReferralDetailFragment extends Fragment implements OnClickListener {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View view = inflater.inflate(R.layout.fragment_referraldetail,container, false);
linkToAcknowledge = (TextView) view.findViewById(R.id.lbl_Link_to_Acknowledge);
return view;
}
}
I implemented a simple solution for this in my app, basically when you press back to go to the fragment again, onCreateView() is called. Here in onCreateView() you have done all initialization, so we change
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View view = inflater.inflate(R.layout.fragment_me, container, false);
/*
*Whatever you want to do
*
*/
return view;
}
to:
View view;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
if(view==null){
view = inflater.inflate(R.layout.fragment_me, container, false);
/*
*Whatever you want to do
*
*/
}
else{
((ViewGroup)view.getParent()).removeView(view);
}
return view;
}
Here, we move View view outside and make it a class variable. So if it is the first time the fragment is called, it is null and the initialization occurs, otherwise it goes to else black. Else block is required because onCreateView() adds whatever it returns as a child of the view's parent, so since view is already there, we remove it and onCreateView automatically adds it again.
According to our exchange in the comments, I completely deletde my answer and re-write a new one.
I copy/paste the code from one of my apps and removing the useless things and changing the names. Hope there is not too many typing mistakes, at that it is the minimum required to have it working.
When I pop back to FirstFragment from SecondFragment, the scroll position of FirstFragment is the same as when I clicked an item to load the SecondFragment.
Note that I don't extend FragmentActivity. I have an activity which loads the fragments.
Extend/modify to match your needs.
MainActivity :
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_layout);
}
}
FirstFragment Class :
public class FirstFragment extends Fragment implements OnItemClickListener {
private ListView mListView;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.first_fragment_layout, container, false);
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
mListView = (ListView) getView().findViewById(R.id.listview_first_fragment);
mListView.setAdapter(mAdapter); // depends on your adapter
mListView.setOnItemClickListener(this);
}
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
mListView.setItemChecked(position, true);
//in case you need, set the bundle here, for example pass the position
Bundle arguments = new Bundle();
arguments.putInt("position", position);
SecondFragment secondFragment = new SecondFragment();
secondFragment.setArguments(arguments);
getFragmentManager().beginTransaction().replace(R.id.fragment_container, secondFragment).addToBackStack(null).commit();
}
}
SecondFragment Class :
public class SecondFragment extends Fragment {
private Integer mPosition;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.second_fragment_layout, container, false);
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
Bundle arguments = getArguments();
if (arguments == null) {
mPosition= 0;
} else {
mPosition= arguments.getInt("Position");
}
}
}
What you are trying to achieve may be done with help of savedInstanceState. i also had this kind of problem which i resolved by using add() method instead of replace() in transition.
If you can change your method or already not using add() than give it a shot.
and if add() method didn't do the trick then check the implementation of savedInstanceState.
correctly save instance state.
How to save states of fragment views.
I have a list fragment on the left of another fragment and is essentially the standard click an item and update the right fragment pattern. When they click an item in the list fragment they are choosing the news article category and I need to keep whatever one is selected when they rotate the device. How do I do that? My current code doesn't work.
My code is as follows:
public class SideMenuFragment extends ListFragment {
ArrayList<SideItem> sideItems;
SideAdapter sideAdapter;
public SideMenuFragment() {
this.setRetainInstance(true);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.list, null);
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
sideItems = new ArrayList<SideItem>();
...add bunch of items
sideAdapter = new SideAdapter(getActivity(), sideItems);
getListView().setVerticalScrollBarEnabled(false);
setListAdapter(sideAdapter);
if (savedInstanceState != null) {
sideAdapter.setSelectedItem(savedInstanceState.getInt("sidePosition"));
sideAdapter.notifyDataSetChanged();
}
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt("sidePosition", sideAdapter.getSelectedItem());
}
#Override
public void onListItemClick(ListView lv, View v, int position, long id) {
if (sideAdapter.getSelectedItem() != position) {
sideAdapter.setSelectedItem(position);
sideAdapter.notifyDataSetChanged();
}
switch (position) {
...switch the fragment depending on position.
}
}
// the meat of switching the above fragment
private void switchFragment(Fragment fragment, String title) {
if (getActivity() == null)
return;
if (getActivity() instanceof HomeActivity) {
HomeActivity a = (HomeActivity) getActivity();
a.switchContent(fragment, title);
}
}
}
First, add your Fragment in xml if the Activity layout.
In Activity onCreate
getFragmentManager().findFragmentById(R.id.youtfragmentid).setRetainInstance(true)
This means that the fragment will not be recreated on activity recreate.
Don't change your ListView in onActivityCreated - because it will be rebuilt every time orientation changes. If you set a new adapter - the states of children will be reseted.
Add checking for null or a boolean flag that the view already was created.
Next time onActivityCreated gets called, your list adapter should not change
if (sideAdapter == null) {
sideAdapter = new SideAdapter(getActivity(), sideItems);
getListView().setVerticalScrollBarEnabled(false);
setListAdapter(sideAdapter);
}
Also, don't create new view in onCreateView instead use previously created one.
private View v;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if (v == null) {
v = inflater.inflate(R.layout.list, null);
} else {
// detatch from container and return the same view
((ViewGroup) getListView().getParent()).removeAllViews();
}
return v;
}
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) {