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;
}
Related
I'm trying to understand the process of saving and restoring state using fragments. I've created sliding navigation menu using it.
In one of the fragments there is this code:
public class FifthFragment extends Fragment {
CheckBox cb;
View view;
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
view = inflater.inflate(R.layout.fifth_layout, container, false);
cb = (CheckBox) view.findViewById(R.id.checkBox);
return view;
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
if (savedInstanceState != null) {
// Restore save state
}
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
// save state
}
}
For example I want to save the state of the CheckBox before user exits the fragment and restore it when the fragment is created again. How to achieve this?
EDIT:
According to raxellson's answer I've changed my fragment to this:
public class FifthFragment extends Fragment {
private static final String CHECK_BOX_STATE = "string";
CheckBox cb;
View view;
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fifth_layout, container, false);
cb = (CheckBox) view.findViewById(R.id.checkBox);
if (savedInstanceState == null) {
Log.i("statenull", "null");
}
if (savedInstanceState != null) {
// Restore last state for checked position.
boolean checked = savedInstanceState.getBoolean(CHECK_BOX_STATE, false);
cb.setChecked(checked);
}
return view;
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putBoolean(CHECK_BOX_STATE, cb.isChecked());
}
}
I got logged I/statenull: null so savedInstanceState was not saved. What am I doing wrong?
You want to save the value of your current checked state in onSaveInstanceState.
Something like this:
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putBoolean(CHECK_BOX_STATE, cb.getChecked());
}
and then when your view is created you want to get the value if it's present. And set your CheckBox state with it.
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fifth_layout, container, false);
cb = (CheckBox) view.findViewById(R.id.checkBox);
if (savedInstanceState != null) {
// Restore last state for checked position.
boolean checked = savedInstanceState.getBoolean(CHECK_BOX_STATE, false);
cb.setChecked(checked);
}
return view;
}
EDIT:
When you add the fragment, make sure to add it with a tag or id so that you can retrieve the same instance.
You could do a helper method to retrieve fragment and set the fragment.
private void setFragment(String tag, Fragment newFragment) {
FragmentManager fm = getSupportFragmentManager();
Fragment savedFragment = fm.getFragmentByTag(tag);
fm.replace(R.id.container, savedFragment != null ? savedFragment : newFragment, tag);
fm.commit();
}
so you your switch you can call the helper method instead.
switch (position) {
case 0:
setFragment("A", new FragmentA());
break;
....
}
Note: This is just an example not best practice since you are creating new fragments every time in your switch case now anyways. But it might point you in the right direction.
After see all the example. Here is the solution for save fragment state:
Two steps for this:
1.
String saveValue;
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (savedInstanceState == null) {
saveValue = "";
} else {
saveValue = savedInstanceState.getString("saveInstance");
}
}
#Override
public void onSaveInstanceState(Bundle savedInstanceState) {
super.onSaveInstanceState(savedInstanceState);
//save the values of fragment if destroy on second to back
if (!saveValue.isEmpty())
savedInstanceState.putString("saveInstance", saveValue);
}
In onSaveInstanceState you can save your values. And after destroy fragment you can receive your values through onCreate.
I am having the "child already has a parent" error close to what a lot of people have been getting, however, I am getting it doing something different (as far as my searches have shown me). I am assuming that the way I am adding the fragment is not necessarily wrong, but I cannot for the life of me figure out how the fragment I am adding already has a parent.
I am launching from my main activity using a fragment to be loaded into a FrameLayout. Here is the onCreate from my main activity:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
realm = Realm.getDefaultInstance();
if (savedInstanceState == null) {
}
tripsFragment = new CarTripsOverview();
getSupportFragmentManager().beginTransaction().add(R.id.content_container, tripsFragment).commit();
}
And here are the methods which run for CarTripsOverview (which is a Fragment):
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
}
setUpRealm();
}
void setUpRealm() {
realm = Realm.getDefaultInstance();
RealmQuery<Car> carQuery = realm.where(Car.class);
RealmResults<Car> carResults = carQuery.findAll();
carAdapter = new CarArrayAdapter(getActivity(),0, carResults, true);
RealmQuery<Trip> tripQuery = realm.where(Trip.class);
RealmResults<Trip> tripResults = tripQuery.findAll();
tripAdapter = new TripAdapterRealm(getActivity(), 0, tripResults, true);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_car_trips_overview, container, true);
// Bind all of the views with Butter Knife
ButterKnife.bind(this, view);
setUpSwipeMenu();
// Add my event listeners
tripListView.setAdapter(tripAdapter);
carSpinner.setAdapter(carAdapter);
return view;
}
void setUpSwipeMenu() {
SwipeMenuCreator creator = new SwipeMenuCreator() {
#Override
public void create(SwipeMenu menu) {
SwipeMenuItem deleteItem = new SwipeMenuItem(getContext());
deleteItem.setBackground(new ColorDrawable(Color.RED));
deleteItem.setWidth(MathHelper.dipToPixels(getContext(), 90));
deleteItem.setTitle("Delete");
deleteItem.setTitleColor(Color.WHITE);
deleteItem.setTitleSize(18);
menu.addMenuItem(deleteItem);
}
};
tripListView.setMenuCreator(creator);
tripListView.setOnMenuItemClickListener(new SwipeMenuListView.OnMenuItemClickListener() {
#Override
public boolean onMenuItemClick(int position, SwipeMenu menu, int index) {
Trip trip = tripAdapter.getItem(position);
switch (index) {
case 0:
delete(trip);
tripAdapter.notifyDataSetChanged();
break;
}
return false;
}
});
}
My biggest problem is that I just don't understand quite where I am adding the child to the parent where it would already have a parent.
All of my source code can be found here.
Instead of:
View view = inflater.inflate(R.layout.fragment_car_trips_overview, container, true);
use:
View view = inflater.inflate(R.layout.fragment_car_trips_overview, container, false);
Notice the last parameter is false now. If you use true, the view you just created will be automatically added to the container (second parameter of inflate). With fragments, always use false in onCreateView(...).
I was having some problems with an activity from my app.
I was saving some data with onSavedInstanceState() and restoring in onCreateView() method (this activity has two fragments and it has onCreate an onCreateView). The data restored were corrected but I could not put them correctly in a spinner from my activity.
I have put some breakpoints before, within and after at this loop:
ArrayAdapter<String> adapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_spinner_item, list);
spinner.setAdapter(adapter);
**if(savedInstanceState != null) {
Log.i("SPINNER POS", ""+posSaved);
spinner.setSelection(posSaved);
}**
and I have could observer that the app access twice to onCreateView method ... the first time the posSaved variable is correct, but the second time this variable is 0 and due to this reason the spinner never shows the position saved in posSaved variable, always it shows the 0 position (like by default) and then is like I do not use onSavedInstanceState method ...
... why app enter twice in onCreateView() method? How can I solve this situation?
PD. This activity also enters twice in onCreate() method.
My Activity CODE
public class Menu_Seeker_Filter extends Fragment {
... (variables declarated) ...
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if ((getFragmentManager().findFragmentById(R.id.results_fragment) != null)) { //Fragments
mTwoPane = true;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.activity_seeker_filtro, container, false);
if (savedInstanceState != null) {
// Restore value of members from saved state
posSaved = savedInstanceState.getInt("POSITION");
}
...
ArrayAdapter<String> adapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_spinner_item, list);
spinner.setAdapter(adapter);
spinner.setOnItemSelectedListener(new OnItemSelectedListener() {
public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) {
((TextView) parent.getChildAt(0)).setTextSize(18);
((TextView) parent.getChildAt(0)).setTypeface(font2);
text = (parent.getItemAtPosition(pos).toString());
posSaved = pos;
}
public void onNothingSelected(AdapterView<?> parent) {
//Do nothing.
}
});
if(savedInstanceState != null) {
Log.i("POSITION", ""+posSaved);
spinner.setSelection(posSaved);
}
}
#Override
public void onSaveInstanceState(Bundle savedInstanceState) {
// Save the user's current game state
savedInstanceState.putInt("POSITION", spinner.getSelectedItemPosition());
// Always call the superclass so it can save the view hierarchy state
super.onSaveInstanceState(savedInstanceState);
}
}
and this activity-fragment is called in this class:
public class Menu_Seeker extends FragmentActivity {
...(variables declarated)...
final Menu_Seeker_Filter fragment = new Menu_Seeker_Filter();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_seeker_filter);
if ((getSupportFragmentManager().findFragmentById(R.id.results_fragment) != null)) { //Fragments
mTwoPane = true;
getSupportFragmentManager().beginTransaction().replace(R.id.seeker_fragment, fragment).commit();
}else { //No Fragments
getSupportFragmentManager().beginTransaction().replace(R.id.framelayout_filter, fragment).commit();
}
...
}
Thanks.
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'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.)