ClassNotFoundException when unmarshalling: android.support.v4.view.ViewPager$SavedState

问题

I am seeing the following error in my Android crash reports:

android.os.BadParcelableException: ClassNotFoundException when unmarshalling: android.support.v4.view.ViewPager$SavedState
at android.os.Parcel.readParcelable(Parcel.java:1971)
at android.os.Parcel.readValue(Parcel.java:1859)
at android.os.Parcel.readSparseArrayInternal(Parcel.java:2128)
at android.os.Parcel.readSparseArray(Parcel.java:1581)
at android.os.Parcel.readValue(Parcel.java:1916)
at android.os.Parcel.readMapInternal(Parcel.java:2099)
at android.os.Bundle.unparcel(Bundle.java:223)
at android.os.Bundle.getSparseParcelableArray(Bundle.java:1225)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:806)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1083)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:635)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1431)
at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:431)
at android.support.v4.app.FragmentStatePagerAdapter.finishUpdate(FragmentStatePagerAdapter.java:160)
at android.support.v4.view.ViewPager.populate(ViewPager.java:895)
at android.support.v4.view.ViewPager.populate(ViewPager.java:772)
at android.support.v4.view.ViewPager.completeScroll(ViewPager.java:1539)
at android.support.v4.view.ViewPager.computeScroll(ViewPager.java:1422)
at android.view.ViewGroup.drawChild(ViewGroup.java:3028)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2788)
at android.view.ViewGroup.drawChild(ViewGroup.java:3184)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2788)
at android.view.ViewGroup.drawChild(ViewGroup.java:3184)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2788)
at android.view.ViewGroup.drawChild(ViewGroup.java:3184)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2788)
at android.view.View.draw(View.java:11017)
at android.widget.FrameLayout.draw(FrameLayout.java:450)
at com.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:2175)
at android.view.ViewRootImpl.draw(ViewRootImpl.java:2234)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1810)
at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2695)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:4977)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
at dalvik.system.NativeStart.main(Native Method)

It appears to happen intermittently when resuming an activity. I do not directly access the SavedState class in any code.

回答1:

I had the same error and here is what I did.

My issue came from using the ViewPager with a FragmentStatePagerAdapter. Inside one of the Fragments from the ViewPager had another ViewPager. Having that second view pager caused this rare bug. Even with or without an adapter on it.

The solution was to simply set setSaveEnabled(false); on the second ViewPager.

回答2:

Following solution worked for me:

package android.support.v4.app;

import android.os.Bundle;
import android.view.ViewGroup;

public abstract class FixedFragmentStatePagerAdapter extends FragmentStatePagerAdapter {

  public FixedFragmentStatePagerAdapter(FragmentManager fm) {
    super(fm);
  }

  @Override
  public Object instantiateItem(ViewGroup container, int position) {
    Fragment f = (Fragment)super.instantiateItem(container, position);
    Bundle savedFragmentState = f.mSavedFragmentState;
    if (savedFragmentState != null) {
      savedFragmentState.setClassLoader(f.getClass().getClassLoader());
    }
    return f;
  }

}

from http://code.google.com/p/android/issues/detail?id=37484#c1

回答3:

If you don't want to include the source in v4 package you can declare the "fix" directly in your Adapter

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        final Object fragment = super.instantiateItem(container, position);
        try {
            final Field saveFragmentStateField = Fragment.class.getDeclaredField("mSavedFragmentState");
            saveFragmentStateField.setAccessible(true);
            final Bundle savedFragmentState = (Bundle) saveFragmentStateField.get(fragment);
            if (savedFragmentState != null) {
                savedFragmentState.setClassLoader(Fragment.class.getClassLoader());
            }
        } catch (Exception e) {
            Log.w("CustomFragmentStatePagerAdapter", "Could not get mSavedFragmentState field", e);
        }
        return fragment;
    }

回答4:

In your Activity/Fragment, do the following:

public void onSaveInstanceState(Bundle outState){
     //This MUST be done before saving any of your own or your base class's     variables
    final Bundle mapViewSaveState = new Bundle(outState);
    mapView.onSaveInstanceState(mapViewSaveState);
    outState.putBundle("mapViewSaveState", mapViewSaveState);
   //Add any other variables here.
   super.onSaveInstanceState(outState);
}

public void onCreate(Bundle savedInstanceState){
   super.onCreate(savedInstanceState);
   final Bundle mapViewSavedInstanceState = savedInstanceState != null ?      savedInstance.getBundle("mapViewSaveState") : null;
 mapView.onCreate(mapViewSavedInstanceState);
 //....
}

source: https://code.google.com/p/gmaps-api-issues/issues/detail?id=6237

or another solution is:

map.onCreate(savedInstanceState);

to this:

map.onCreate(null);