android - ViewPager: Recursive entry to executePendingTransactions

Question

I have a ViewPager within a ViewPager and I am getting this exception

09-07 18:30:26.392: ERROR/AndroidRuntime(841): FATAL EXCEPTION: main
    java.lang.IllegalStateException: Recursive entry to executePendingTransactions
    at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1331)
    at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:422)
    at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:86)
    at android.support.v4.view.ViewPager.populate(ViewPager.java:453)
    at android.support.v4.view.ViewPager.onAttachedToWindow(ViewPager.java:563)
    at android.view.View.dispatchAttachedToWindow(View.java:7974)
    at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1857)
    at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1862)
    at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1862)
    at android.view.ViewGroup.addViewInner(ViewGroup.java:2968)
    at android.view.ViewGroup.addView(ViewGroup.java:2824)
    at android.support.v4.view.ViewPager.addView(ViewPager.java:537)
    at android.view.ViewGroup.addView(ViewGroup.java:2781)
    at android.view.ViewGroup.addView(ViewGroup.java:2761)
    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:848)
    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1041)
    at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:616)
    at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1359)
    at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:422)
    at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:86)
    at android.support.v4.view.ViewPager.populate(ViewPager.java:453)
    at android.support.v4.view.ViewPager.onAttachedToWindow(ViewPager.java:563)
    at android.view.View.dispatchAttachedToWindow(View.java:7974)
    at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1857)
    at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1862)
    at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1862)
    at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1862)
    at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1862)
    at android.view.ViewRoot.performTraversals(ViewRoot.java:726)
    at android.view.ViewRoot.handleMessage(ViewRoot.java:1944)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:126)
    at android.app.ActivityThread.main(ActivityThread.java:3997)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:491)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
    at dalvik.system.NativeStart.main(Native Method)

I am not really sure where this error comes from and I don't know too much about the FragmentManager. Do I need to flush the transactions or something like that? Or is a viewPager within a ViewPager impossible? And yes I know there are other ways to do this but I want the snappness and the scrolling for free. Also I would like to understand how it actually works.

Answer 1

New version of Support Library v4 (or Android 4.2, ofcourse) resolve this problem much simply. For do this, simply do constructor of your custom FragmentPagerAdapter like this:

public CustomFragmentPagerAdapter(android.support.v4.app.Fragment fragment)
{
    super(fragment.getChildFragmentManager());

    // write your code here
}

This work because new Android version approve using nested Fragments