[android-developers] Re: FragmentManager.popBackStack not working when used with child fragment manager

I had the same problem. The solution for me was simple:

in onCreateView I had:

// Create the adapter that will return a fragment for each of the three  // primary sections of the app.  mSectionsPagerAdapter = new SectionsPagerAdapter(getActivity()      .getSupportFragmentManager());

where SectionPageAdapter is something like this:

class SectionsPagerAdapter extends FragmentPagerAdapter {  ...  }

after changing getSupportFragmentManager to

mSectionsPagerAdapter = new SectionsPagerAdapter(getChildFragmentManager());

it started working! Hope this helps.

Am Samstag, 25. Mai 2013 15:08:13 UTC+2 schrieb Miha:

Hi!

Starting a new topic from https://groups.google.com/forum/?fromgroups#!topic/android-developers/WgokX2uhv88; I have a situation where I'm using ViewPager to flip between fragments, and two of the fragments have nested fragments.

Fragment nesting is done via getChildFragmentManager and orientation changes work as expected (fragments implement onSaveInstanceState), but when trying to pop the backstack after user interactions, I just get a NullPointerException or an "IllegalStateException: Activity has been destroyed" depending on whether I use popBackStack or popBackStackImmediate.

If I dump the child fragment state, it shows the activity as detached; If I dump the "parent" fragment manager state, it shows all of the fragments and also the activity reference (see below).

I'm using support library, and with that, I'm using classes from android.support.v4.app package.

Child fragment state:

FragmentManager misc state:

  mActivity=null

  mContainer=android.support.v4.app.Fragment$1@41603ca0

  mParent=MainFilesFragment{4169ccf0}

  mCurState=0 mStateSaved=false mDestroyed=false

Parent fragment state:

Active Fragments in 414896e0:

  #0: null

  #1: ConnectFragment{41505ae0 #1 id=0x7f060001}

    mFragmentId=#7f060001 mContainerId=#7f060001 mTag=null

    mState=5 mIndex=1 mWho=android:fragment:1 mBackStackNesting=0

    mAdded=true mRemoving=false mResumed=true mFromLayout=false mInLayout=false

    mHidden=false mDetached=false mMenuVisible=false mHasMenu=false

    mRetainInstance=false mRetaining=false mUserVisibleHint=false

    mFragmentManager=FragmentManager{414896e0 in MainActivity{41489470}}

    mActivity=com.islonline.isllightdesign.MainActivity@41489470

    mContainer=android.support.v4.view.ViewPager{4145c668 VFED.... ........ 0,0-800,1033 #7f060001 app:id/pager}

    mView=android.support.v4.app.NoSaveStateFrameLayout{414b1258 V.E..... ........ 800,0-1600,1033}

    mInnerView=android.support.v4.app.NoSaveStateFrameLayout{414b1258 V.E..... ........ 800,0-1600,1033}

  #2: MainFilesFragment{4155a430 #2 id=0x7f060001}

    mFragmentId=#7f060001 mContainerId=#7f060001 mTag=null

    mState=5 mIndex=2 mWho=android:fragment:2 mBackStackNesting=0

    mAdded=true mRemoving=false mResumed=true mFromLayout=false mInLayout=false

    mHidden=false mDetached=false mMenuVisible=true mHasMenu=false

    mRetainInstance=false mRetaining=false mUserVisibleHint=true

    mFragmentManager=FragmentManager{414896e0 in MainActivity{41489470}}

    mActivity=com.islonline.isllightdesign.MainActivity@41489470

    mContainer=android.support.v4.view.ViewPager{4145c668 VFED.... ........ 0,0-800,1033 #7f060001 app:id/pager}

    mView=android.support.v4.app.NoSaveStateFrameLayout{4155bcf8 V.E..... ........ 1600,0-2400,1033}

    mInnerView=android.support.v4.app.NoSaveStateFrameLayout{4155bcf8 V.E..... ........ 1600,0-2400,1033}

    Child FragmentManager{4155b598 in MainFilesFragment{4155a430}}:

      Active Fragments in 4155b598:

        #0: ComputerListFragment{4155b7b8 #0 id=0x7f060010 COMPUTER_LIST}

          mFragmentId=#7f060010 mContainerId=#7f060010 mTag=COMPUTER_LIST

          mState=1 mIndex=0 mWho=android:fragment:2:0 mBackStackNesting=1

          mAdded=false mRemoving=true mResumed=false mFromLayout=false mInLayout=false

          mHidden=false mDetached=false mMenuVisible=true mHasMenu=false

          mRetainInstance=false mRetaining=false mUserVisibleHint=true

          mFragmentManager=FragmentManager{4155b598 in MainFilesFragment{4155a430}}

          mActivity=com.islonline.isllightdesign.MainActivity@41489470

          mParentFragment=MainFilesFragment{4155a430 #2 id=0x7f060001}

          mSavedViewState=android.util.SparseArray@41690a60

        #1: FileShareBrowserFragment{41690840 #1 id=0x7f060010}

          mFragmentId=#7f060010 mContainerId=#7f060010 mTag=null

          mState=5 mIndex=1 mWho=android:fragment:2:1 mBackStackNesting=1

          mAdded=true mRemoving=false mResumed=true mFromLayout=false mInLayout=false

          mHidden=false mDetached=false mMenuVisible=true mHasMenu=false

          mRetainInstance=false mRetaining=false mUserVisibleHint=true

          mFragmentManager=FragmentManager{4155b598 in MainFilesFragment{4155a430}}

          mActivity=com.islonline.isllightdesign.MainActivity@41489470

          mParentFragment=MainFilesFragment{4155a430 #2 id=0x7f060001}

          mContainer=android.widget.FrameLayout{4155b210 V.E..... ........ 0,0-800,1033 #7f060010 app:id/file_browser_container}

          mView=android.support.v4.app.NoSaveStateFrameLayout{41698148 V.E..... ........ 0,0-800,1033}

          mInnerView=android.support.v4.app.NoSaveStateFrameLayout{41698148 V.E..... ........ 0,0-800,1033}

        #2: null

      Added Fragments:

        #0: FileShareBrowserFragment{41690840 #1 id=0x7f060010}

      Back Stack:

        #0: BackStackEntry{41690780 #0}

          mName=null mIndex=0 mCommitted=true

          Operations:

            Op #0: REPLACE FileShareBrowserFragment{41690840 #1 id=0x7f060010}

              Removed: ComputerListFragment{4155b7b8 #0 id=0x7f060010 COMPUTER_LIST}

      Back Stack Indices:

        #0: BackStackEntry{41690780 #0}

Thanks,

 Miha.

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