Java 键f0的片段不再存在：索引0

我有4个碎片。和导航抽屉。在我第一次从1个片段移动到2个片段之后，一切都很好。两次之后，我从1块碎片移动到2块，一切都很好

但当我试着从1个碎片到2个碎片时，我试了3次。他犯了这个错误

---

我理解ViewPager的问题。但我不知道在哪里挖掘。需要帮助开发者

Hi。。这个问题有什么解决办法吗？

FATAL EXCEPTION: main
      Process: com.riyadbankacademy, PID: 23795
      Theme: themes:{default=overlay:system, iconPack:system, fontPkg:system, com.android.systemui=overlay:system, com.android.systemui.navbar=overlay:system}
      java.lang.IllegalStateException: Fragment no longer exists for key f0: index 0
      at android.support.v4.app.FragmentManagerImpl.getFragment(FragmentManager.java:879)
      at android.support.v4.app.FragmentStatePagerAdapter.restoreState(FragmentStatePagerAdapter.java:215)
      at android.support.v4.view.ViewPager.onRestoreInstanceState(ViewPager.java:1481)
      at android.view.View.dispatchRestoreInstanceState(View.java:14756)
      at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:3121)
      at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:3127)
      at android.view.View.restoreHierarchyState(View.java:14734)
      at android.support.v4.app.Fragment.restoreViewState(Fragment.java:475)
      at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1329)
      at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1528)
      at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1595)
      at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:758)
      at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2363)
      at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2149)
      at android.support.v4.app.FragmentManagerImpl.optimizeAndExecuteOps(FragmentManager.java:2103)
      at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2013)
      at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:710)
      at android.os.Handler.handleCallback(Handler.java:739)
      at android.os.Handler.dispatchMessage(Handler.java:95)
      at android.os.Looper.loop(Looper.java:148)
      at android.app.ActivityThread.main(ActivityThread.java:5461)
      at java.lang.reflect.Method.invoke(Native Method)
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

public class LibraryViewPagerAdapter extends FragmentStatePagerAdapter {
    private int size=0;

    public LibraryViewPagerAdapter(FragmentManager fm, int size) {
        super(fm);
        this.size = size;
    }

    @Override
    public Fragment getItem(int position) {
        Log.e("LibraryViewPagerAdapter=getItem", position + "");
        return new LibraryPageFragment(position);
    }

    @Override
    public int getCount() {
        return size;
    }
}