I am working on an Android app and have encountered an error involving Fragments and FragmentTransactions. I have created an example app to demonstrate the problem. Here is what I am doing:
add
Fragment1
to fragmentSpace
, without adding to backstack. replace
fragmentSpace
with Fragment2
, adding to backstack as "beginning"
. add
Fragment3
to fragmentSpace2
(which is inside of Fragment2
), without adding to backstack. replace
fragmentSpace2
with Fragment4
, adding to backstack as null
. getFragmentManager().popBackStack("beginning", FragmentManager.POP_BACK_STACK_INCLUSIVE);
in an attempt to undo all the Transactions, which should bring the user back to seeing only Fragment1
. However, the app crashes on step 5 with this error:
java.lang.IllegalArgumentException: No view found for id 0x7f090004 (me.MitchT.testfragmenttransactions:id/fragmentSpace2) for fragment Fragment3{7f35cb6 #2 id=0x7f090004}
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:886)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
at android.app.BackStackRecord.popFromBackStack(BackStackRecord.java:1645)
...
I have found that if I add step 3 to the backstack, step 5 no longer crashes the app and there is no more error. Why?
The problem I have with adding step 3 to the backstack is that I want the user to be able to press the back button after Fragment3
is added and go back to Fragment1
. If I add it to the backstack, then when the user presses the back button it removes Fragment3
, but Fragment2
is still visible, so they must press the back button again . I am trying to avoid that double-back-button behavior.
I did not feel it was necessary to post the code for every single file in the example app on this question, so instead I created a gist.
So I guess my questions are:
Thanks!
From what i understand. You have a fragment layout which is the container in activity
Activity hosts Fragment1. Then you replace Fragment 1 by Fragment 2 ( added to back stack.
At this stage clicking back button you will have fragment2 popped and you see the activity which hosts fragment1.
Fragment2 has a framelayout which holds fragment3. Then you have Fragment4 replacing fragment3 which is added to back stack.
Now clicking the button you have getFragmentManager().popBackStack("beginning", FragmentManager.POP_BACK_STACK_INCLUSIVE);
. But there is no view with that id.
Just use popBackStack()
. Fragment4 --> Fragment2 ( hosting fragment3) --> Fragment1 ( hosted by the activity).
If you want Fragment4 to Activity hosting Fragment1 don't add Fragment4 to the back stack.
Note : In case you want nested fragments you need to use getChildFragmentManager()
. https://developer.android.com/about/versions/android-4.2.html
Also note the discussion in the comments sections and the link posted by op Is this the right way to clean-up Fragment back stack when leaving a deeply nested stack?
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