片段的childfragmentmanager getFragments（）在替換後返回null

我有MainActivity並且裏面有一個FragmentLayout。當使用此代碼選擇標籤（如instagram）時，我在該佈局中顯示不同的片段。片段的childfragmentmanager getFragments（）在替換後返回null

MABaseFragment fragment = mBackStackOfFragment.get(getStackNo(stack)).peek(); 
ft.replace(R.id.contentFrame, fragment). 
currentVisibleFragment = fragment;

在該片段我有Viewpager與母體片段的創建childfragmentmanager之一。我用此代碼創建父代片段

public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { 

    List asd = getChildFragmentManager().getFragments(); 
    if(view == null) 
    { 
     view = inflater.inflate(R.layout.fragment_search, container, false); 
     setHasOptionsMenu(false); 

     actionBar = MAMainActivity.mainActivity.getSupportActionBar(); 
     mViewPager = (ViewPager) view.findViewById(R.id.pager); 
     mSlidingTabLayout = (SlidingTabLayout) view.findViewById(R.id.pager_title_strip); 

     mViewPager.setOffscreenPageLimit(numberOfTabs); 
     mSlidingTabLayout.setDistributeEvenly(true); 
     pagerAdapter = new MASearchFPA(getContext(), getChildFragmentManager()); 
     mViewPager.setAdapter(pagerAdapter); 

     mSlidingTabLayout.setViewPager(mViewPager); 

     mSlidingTabLayout.setCustomTabColorizer(new SlidingTabLayout.TabColorizer() { 
      @Override 
      public int getIndicatorColor(int position) { 
       return getResources().getColor(R.color.colorPrimary); 
      } 

      @Override 
      public int getDividerColor(int position) { 
       return getResources().getColor(R.color.colorPrimary); 
      } 
     }); 
    } 
    return view; 
}

而且我保留每個片段的參考，因爲允許用戶繼續他們離開的地方。它運作良好，與不具有嵌套的片段，但是當這個分片嵌套應用程序替換當前片段等片段崩潰

01-11 12:36:08.239 20857-20857/tr.com.meeapps.livyapp E/AndroidRuntime: FATAL EXCEPTION: main 
                     Process: tr.com.meeapps.livyapp, PID: 20857 
                     java.lang.IllegalStateException: Fragment no longer exists for key f0: index 0 
                      at android.support.v4.app.FragmentManagerImpl.getFragment(FragmentManager.java:692) 
                      at android.support.v4.app.FragmentStatePagerAdapter.restoreState(FragmentStatePagerAdapter.java:215) 
                      at android.support.v4.view.ViewPager.onRestoreInstanceState(ViewPager.java:1453) 
                      at android.view.View.dispatchRestoreInstanceState(View.java:15637) 
                      at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:3268) 
                      at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:3274) 
                      at android.view.View.restoreHierarchyState(View.java:15615) 
                      at android.support.v4.app.Fragment.restoreViewState(Fragment.java:477) 
                      at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1135) 
                      at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1290) 
                      at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:801) 
                      at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1677) 
                      at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:536) 
                      at android.os.Handler.handleCallback(Handler.java:751) 
                      at android.os.Handler.dispatchMessage(Handler.java:95) 
                      at android.os.Looper.loop(Looper.java:154) 
                      at android.app.ActivityThread.main(ActivityThread.java:6077) 
                      at java.lang.reflect.Method.invoke(Native Method) 
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)

，因爲我認爲childfragmentmanager的mActive列表是空替代方法曾經被稱爲後是返回null到Viewpager 。

所以我不知道爲什麼孩子片段的mActive片段在更換後爲空。有什麼辦法來防止這種行爲。謝謝。

編輯

我的適配器類

public class MASearchFPA extends FragmentStatePagerAdapter { 
    Context context; 
    MACategoriesFragment categoriesFragment; 
    MAMapFragment mapFragment; 
    MAFavoritesFragment favoritesFragment; 
    FragmentManager fm; 
    public MASearchFPA(Context context, FragmentManager fm) { 
     super(fm); 
     this.context = context; 

     this.fm = fm; 
     categoriesFragment = new MACategoriesFragment(); 
     mapFragment = new MAMapFragment(); 
     favoritesFragment = new MAFavoritesFragment(); 
    } 

    @Override 
    public Fragment getItem(int position) { 

     if(position == 0) // if the position is 0 we are returning the First tab 
     { 
      return categoriesFragment; 
     } 
     else if(position == 1)    // As we are having 2 tabs if the position is now 0 it must be 1 so we are returning second tab 
     { 
      return mapFragment; 
     } 
     else 
     { 
      return favoritesFragment; 
     } 
    } 

    @Override 
    public int getCount() { 
     return MASearchFragment.numberOfTabs; 
    } 

    @Override 
    public CharSequence getPageTitle(int position) { 
     switch (position) { 
      case 0: 
       return context.getResources().getString(R.string.categories); 
      case 1: 
       return context.getResources().getString(R.string.map); 
      case 2: 
       return context.getResources().getString(R.string.favorites); 
      default: 
       return null; 
     } 
    }

來源

2017-01-11 Demirhan Karademir

我solwed問題與顯示和隱藏方法。因爲replace方法會銷燬片段的子片段的引用。與顯示和隱藏片段相對solwed我的問題。

來源

2017-01-20 11:34:04

片段的childfragmentmanager getFragments（）在替換後返回null

回答

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