When I start my app it runs an AsyncTask to load up and then in onPostExecute, I then setContentView to the new layout then add a fragment with two buttons offering two modes by an add FragmentTransaction. After one of the two modes is clicked, it then replaces the fragment with yet another FragmentTransaction using the replace method.
If the app crashes it returns to the first screen, loading up the two buttons offering the two modes. In this case if either mode is selected, the second fragment is loaded but is now the background is suddenly transparent showing the two buttons below and they remain clickable. If they are clicked again they properly replace the fragment so that it isn't visible below. This is just weird, I can't understand what could cause this.
I've researched and seen these two similar questions, one and two, which suggested that it might be because the ID is wrong or I have defined the fragment in XML. Neither of these two factors are the case.
My code is shown below:
Below I replace the loading screen.
#Override
protected void onPostExecute(Void result) {
setContentView(R.layout.activity_main_screen);
FragmentTransaction transaction = getSupportFragmentManager()
.beginTransaction();
transaction.add(R.id.fragment_container, new ModeFragment())
.commit();
}
After which, when a button is clicked I pass the fragment I wish to replace the current with into this method below:
private void replaceCurrentFragment(Fragment fragment) {
FragmentTransaction transaction = getSupportFragmentManager()
.beginTransaction();
transaction.replace(R.id.fragment_container, fragment)
.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN)
.addToBackStack(null).commit();
}
This works the first time, however if a crash occurs then the app returns to the first fragment and the second time this method is passed, the new replacing fragment is semi-invisible. Clicking the button on the first fragment again calls this method again and it is now fine.
Obviously I don't want the app to crash so this shouldn't occur, but I get this feeling that there's something wrong with how I'm writing my code.
I've had the same problem happen to me, and it was because I loaded a fragment in the OnCreate of my Activity, without checking if there was a savedInstanceState, so android first reopen all old fragments, then do the OnCreate, which added the fragment over the old ones without replacing them so when you navigate to another fragment, it only replaces the top one, but not the bottom one, so you will see the fragments under it.
Might not be exactly the same thing for you, but it might help you figure it out.
Related
I read many threads to this topic but nothing could help me.
I can´t post my code, but i try to explain my situation:
I´m getting an IllegalStateException: can not perform this action after onSaveInstanceState
I have an activity Main (with an DrawerLayout / navigation drawer). In this activity is always 1 fragment. At first there is the fragment WelcomePage.
When the user clicks the fragment gets replaced with new fragment (I call it: FootballClubs). This fragment contains a ViewPager, so it consists of multi pages; each page is a fragment FootballClub. (So the fragment FootballClubs consists of multi pages of one FootballClub fragment). In each FootballClub fragment is a button where the user can click; on click opens a new fragment (I call it NewFragment).
At first, everything is ok and no exception is thrown. I can click the button as often as possible, each time the new fragment is shown correctly without an exception, and onBackPressed I get back to FootballClubs with the ViewPager. But when I turn my smartphone, screen orientation has changed at least one time, I get following exception when I click on the button to open the new fragment (whatever fragment I want to show):
IllegalStateException: can not perform this action after onSaveInstanceState
I replace the fragments WelcomePage/FootballClubs/NewFragment with this code:
protected void replaceSubfragment(int containerID, Fragment newFragment) {
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(containerID, newFragment);
transaction.commit();
}
The exception is thrown in transaction.commit();
containerID is always the same (FrameLayout in activity layout)
Some additional information:
If I replace
transaction.commit();
with
transaction.commitAllowingStateLoss();
I get this Exception: IllegalStateException: Activity has been destroyed (although I click/do exactly the same)
All fragments gets replaced in my FragmentActivity class Main; When you click on the button, the Subclass of SectionPage gets noticed and calls a listener from FragmentActivity, so that the FragmentActivity can replace the fragments (BaseActivity gives the listener over to FootballClubs fragment, and this gives it over to the Subclass of SectionPage)
Due to the fact that I only replace fragments in my FragmentActivity I don´t use getChildFragmentManager(); (As far as I can remember this didn´t work too)
I know that the activity gets destroyed and recreated by the system when orientation changed, but I can´t do something with this information.. the whole app works perfectly except this button
If I want to show a dialog instead of NewFragment on button click I get an IllegalStateException too
In my FragmentActivity, I have a variable activeModule; here I can check activeModule.isAdded(); When the exception is thrown, isAdded() return false.. So I can check if the error will be thrown or not
I hope I could describe my problem. The screen orientation ruins everything, don´t know why..
If you need further information ask me.. if you need some code pieces maybe I can post something.
Thanks!
I'm working on a application which has Single activity rest all fragments...
This issue i'm facing occurs occasionally.. like when ever i press back button from any of the fragment the previous fragment appears... but sometimes it happens that My activity shows blank screen with action bar present, and rest of the screen is blank instead of showing the fragment... Since this issue appears occasionally i'm not able to debug it also... Any idea why it happens so??
Here is the code fragment transaction..
private void loadFragment(Fragment fragment, int activityNumber) {
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction trnx = manager.beginTransaction();
trnx.replace(R.id.fragPage, fragment, "Current_Fragment");
if (activityNumber != FragmentActivityNumbers.HOME_ORDERNUM) {
trnx.addToBackStack(null);
}
trnx.commit();
}
I suggest to test if its the first fragment so you use Add instead of replace then you can use replace for the others fragments .
I am having a pretty big issue and I am not quite understanding what is happening. I am developing an application that uses Fragments (from the support library) and am using FragmentTransaction.replace() to place new Fragments on to the back stack and replace the old one. The code looks as follows:
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction ft = ft.beginTransaction();
// Animations in my res/anim folder
ft.setCustomAnimations(R.anim.slide_in_right, R.anim.slide_out_left, R.anim.slide_in_left, R.anim.slide_out_right);
ft.replace(R.id.fragment_container, newFragment, tag);
ft.addToBackStack(null);
ft.commit();
This is successful in replacing my fragment. My issue is the following. In one Fragment, I have a list of items that is built from user input. Now, when the user clicks next and then clicks the back button (to return to the list), the list is empty because the view is destroyed. Now, I have noted the following:
onSaveInstanceState is not called. I believe this is because that is only called when the parent Activity tells it to. Based on the docs: " 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.". Apparently, performing a replace on the FragmentTransaction is not one of those times. Does anyone have confirmation on this or a better explanation?
setOnRetainInstanceState(true) is not helpful in this situation. Again, I believe this has to do with info from the docs: "Control whether a fragment instance is retained across Activity re-creation (such as from a configuration change)". I am not performing any action in re-creating the activity so this is of no use.
So, I guess my main question is: is there a way to preserve the View state (simply retain the Fragment) when using replace? There is FragmentTransaction.add(), but there are a few issues with this as well. One being that the exit animation is not performed, thus the animation is not correct. Another is that the new Fragment that the old fragment (the one that is being put into a non-visible state) is still clickable. For example, if I have a ListFragment, and I place a content fragment on top of that by using add, I can still click the list items in the ListFragment.
Without being able to see the code of your fragments this is a bit of a guess, but in the past I've run into this same issue and I've found that resetting the adapter in your ListFragment in onViewStateRestored seems to do the trick.
public void onViewStateRestored (Bundle savedInstanceState)
{
super.onViewStateRestored (savedInstanceState);
setListAdapter(new ArrayAdapter(Activity, R.layout.nav_item, objects));
}
Which is weird considering the documentation states that this method is called after onActivityCreated but before onStart. But it seems that it is also called at other times because when the most recent fragment transaction is popped off the back stack this method is called before the previously replaced fragment is displayed. The activity that owns the fragments has not been paused or obscured in any way, so according to the docs onViewStateRestored should not be called since just the fragments were modified. But this seems to work anyway.
It sounds like you simply need to make sure you have properly implemented onCreateView and onDestroyView. The situation you are describing seems to indicate that when the list fragment is put on the back stack (as a result of the replace transaction) Android is calling onDestroyView to free up some resources. However, it apparently has not destroyed the list fragment because when you tap back you are getting back the same instance of the fragment.
Assuming this is all true then, when the user taps back Android will call onCreateView. Any state that you have stored in the fragment's instance variables should still be there and all you need to do is repopulate the view...perhaps set the adapter on the ListView or whatever.
Also make sure your onSaveInstanceState() callback actually does save any instance state that you need to rebuild the view. That way if the fragment actually does get completely destroyed the FragmentManager can restore the state when it needs to recrete the fragment later.
Scenario what i'm trying to achieve:
Loading activity with two frame containers (for list of items and for details).
At the app launch time add listFragment in listFrame and some initial infoFragment in detailsFrame containers.
Navigating through list items without adding each detail transaction to back stack (want to keep only infoFragment in stack).
As soon as user hit back button (navigate back) he falls back to intial infoFragment what was added in launch time.
If sequential back navigation fallows then apps exit.
My code:
protected override void OnCreate(Bundle savedInstanceState)
{
...
var listFrag = new ListFragment();
var infoFrag = new InfoFragment();
var trans = FragmentManager.BeginTransaction();
trans.Add(Resource.Id.listFrame, listFrag);
trans.Add(Resource.Id.detailsFrame, infoFrag);
trans.Commit();
...
}
public void OnItemSelected(int id)
{
var detailsFrag = DetailFragment.NewInstance(id);
var trans = FragmentManager.BeginTransaction();
trans.Replace(Resource.Id.detailsFrame, detailsFrag);
if (FragmentManager.BackStackEntryCount == 0)
{
trans.AddToBackStack(null);
}
trans.Commit();
}
My problem:
After back button has been hit, infoFrag is overlapped with previous detailFrag! Why?
You can do this:
if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
getSupportFragmentManager().popBackStack(getSupportFragmentManager().getBackStackEntryAt(0).getId(), getSupportFragmentManager().POP_BACK_STACK_INCLUSIVE);
} else {
super.onBackPressed();}
In your activity, so you to keep first fragment.
You shouldn't have, in your first fragment, the addToBackStack. But, in the rest, yes.
Very nice explanation by Budius. I read his advice and implemented similar navigation, which I would like to share with others.
Instead of replacing fragments like this:
Transaction.remove(detail1).add(detail2)
Transaction.remove(detail2).add(detail3)
Transaction.remove(detail3).add(detail4)
I added a fragment container layout in the activity layout file. It can be either LinearLayout, RelativeLayot or FrameLayout etc.. So in the activity on create I had this:
transaction.replace(R.id.HomeInputFragment, mainHomeFragment).commit();
mainHomeFragment is the fragment I want to get back to when pressing the back button, like infoFrag. Then, before EVERY NEXT transaction I put:
fragmentManager.popBackStackImmediate();
transaction.replace(R.id.HomeInputFragment, frag2).addToBackStack(null).commit();
or
fragmentManager.popBackStackImmediate();
transaction.replace(R.id.HomeInputFragment, frag3).addToBackStack(null).commit();
That way you don't have to keep track of which fragment is currenty showing.
The problem is that the transaction that you're backing from have two steps:
remove infoFrag
add detailsFrag (that is the first1 detail container that was added)
(we know that because the documentation This is essentially the same as calling remove(Fragment) for all currently added fragments that were added with the same containerViewId and then add(int, Fragment, String) with the same arguments given here. )
So whenever the system is reverting that one transaction is reverting exactly those 2 steps, and it say nothing about the last detailFrag that was added to it, so it doesn't do anything with it.
There're two possible work arounds I can think on your case:
Keep a reference on your activity to the last detailsFrag used and use the BackStackChange listener to whenever the value change from 1 to 0 (you'll have to keep track of previous values) you also remove that one remaining fragment
on every click listener you'll have to popBackStackImmediatly() (to remove the previous transaction) and addToBackStack() on all transactions. On this workaround you can also use some setCustomAnimation magic to make sure it all looks nice on the screen (e.g. use a alpha animation from 0 to 0 duration 1 to avoid previous fragment appearing and disappearing again.
ps. I agree that the fragment manager/transaction should be a bit more clever to the way it handles back stack on .replace() actions, but that's the way it does it.
edit:
what is happening is like this (I'm adding numbers to the details to make it more clear).
Remember that .replace() = .remove().add()
Transaction.remove(info).add(detail1).addToBackStack(null) // 1st time
Transaction.remove(detail1).add(detail2) // 2nd time
Transaction.remove(detail2).add(detail3) // 3rd time
Transaction.remove(detail3).add(detail4) // 4th time
so now we have detail4 on the layout:
< Press back button >
System pops the back stack and find the following back entry to be reversed
remove(info).add(detail1);
so the system makes that transaction backward.
tries to remove detail1 (is not there, so it ignores)
re-add(info) // OVERLAP !!!
so the problem is that the system doesn't realise that there's a detail4 and that the transaction was .replace() that it was supposed to replace whatever is in there.
You could just override onBackPressed and commit a transaction to the initial fragment.
I'm guessing but:
You've added the transaction to replace infoFrag with 1st detailsFrag into the backstack.
But then you replace 1st detailsFrag with 2nd detailsFrag.
At this point when you click back, the fragment manager cannot cleanly replace 1st detailsFrag with infoFrag as 1st detailsFrag has already been removed and replaced.
Whether the overlapping behaviour is expected or not I don't know.
I would suggest debugging the Android core code to see what it is doing.
I'm not sure whether you can achieve without say overriding Activity::onBackPressed() and doing the pops yourself having added all transactions to the backstack.
In my application i have one activity and i am adding two fragments at run time.I need to swap these two fragment simultaneously. Fragment 1 consist a button and i want when i click that button fragment 1 moves to right side of the screen and other fragment to the left side of the activity.
In the onClick method of the button i tried something like this
#Override
public void onClick(View v) {
FragmentTransaction ft = getFragmentManager().beginTransaction();
Fragment newFragment = getFragmentManager().findFragmentById(R.id.pageA);
ft.remove(newFragment);
Fragment newFragmentB = getFragmentManager().findFragmentById(R.id.pageB);
ft.remove(newFragmentB);
ft.add(R.id.pageB, newFragment);
ft.add(R.id.pageA, newFragmentB);
ft.addToBackStack(null);
ft.commit();
}
But i am getting the following error
java.lang.IllegalStateException: Can't change container ID of fragment PageA{40653da0 #0 id=0x7f060001}: was 2131099649 now 2131099650
I want something like this when i click the button on Page A then Position of Page A and PageB should swap with each other.
I have a similar issue ( IllegalStateException: Can't change container ID of Fragment ) and i solved by swapping the containers instead of the fragments... Nonetheless i still have no clue as to whether it's possibile to swap directly fragments. As I wrote in the aforementioned post, it seems to work only on ics!
I posted a solution to this problem to a similar question. My approach is to re-create the fragment, but keeping the state by saving it first and re-applying it to the new instance.
See https://stackoverflow.com/a/14951987/599614.