更改屏幕方向時為什么會有ClassNotFoundException？

Question

旋轉設備時出現ClassNotFoundException。 將admob庫com.google.android.gms：play-services-ads：17.2.0添加到我的項目后，發生了錯誤。 沒有這個庫，一切都會正常。

我試圖將庫版本更改為16.0.0，在此版本中不需要應用程序ID，不會發生錯誤。

2019-04-09 19:32:16.164 12689-12718/com.example.example.myapplication E/Parcel: Class not found when unmarshalling: android.support.v4.app.FragmentManagerState
    java.lang.ClassNotFoundException: android.support.v4.app.FragmentManagerState
        at java.lang.Class.classForName(Native Method)
        at java.lang.Class.forName(Class.java:400)
        at android.os.Parcel.readParcelableCreator(Parcel.java:2564)
        at android.os.Parcel.readParcelable(Parcel.java:2518)
        at android.os.Parcel.readValue(Parcel.java:2421)
        at android.os.Parcel.readArrayMapInternal(Parcel.java:2788)
        at android.os.BaseBundle.unparcel(BaseBundle.java:271)
        at android.os.Bundle.getBundle(Bundle.java:817)
        at fw.onActivityCreated(:com.google.android.gms.dynamite_measurementdynamite@16089051@16.0.89 (040408-239467275):33)
        at com.google.android.gms.measurement.internal.AppMeasurementDynamiteService.onActivityCreated(:com.google.android.gms.dynamite_measurementdynamite@16089051@16.0.89 (040408-239467275):145)
        at cf.a(:com.google.android.gms.dynamite_measurementdynamite@16089051@16.0.89 (040408-239467275):160)
        at k.onTransact(:com.google.android.gms.dynamite_measurementdynamite@16089051@16.0.89 (040408-239467275):4)
        at android.os.Binder.transact(Binder.java:499)
        at com.google.android.gms.internal.measurement.zzq.zza(Unknown Source)
        at com.google.android.gms.internal.measurement.zzdp.onActivityCreated(Unknown Source)
        at com.google.android.gms.internal.measurement.zzex.zzgd(Unknown Source)
        at com.google.android.gms.internal.measurement.zzea$zzb.run(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
        at java.lang.Thread.run(Thread.java:760)
     Caused by: java.lang.ClassNotFoundException: android.support.v4.app.FragmentManagerState
        at java.lang.Class.classForName(Native Method)
        at java.lang.BootClassLoader.findClass(ClassLoader.java:1346)
        at java.lang.BootClassLoader.loadClass(ClassLoader.java:1406)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
        at java.lang.Class.classForName(Native Method) 
        at java.lang.Class.forName(Class.java:400) 
        at android.os.Parcel.readParcelableCreator(Parcel.java:2564) 
        at android.os.Parcel.readParcelable(Parcel.java:2518) 
        at android.os.Parcel.readValue(Parcel.java:2421) 
        at android.os.Parcel.readArrayMapInternal(Parcel.java:2788) 
        at android.os.BaseBundle.unparcel(BaseBundle.java:271) 
        at android.os.Bundle.getBundle(Bundle.java:817) 
        at fw.onActivityCreated(:com.google.android.gms.dynamite_measurementdynamite@16089051@16.0.89 (040408-239467275):33) 
        at com.google.android.gms.measurement.internal.AppMeasurementDynamiteService.onActivityCreated(:com.google.android.gms.dynamite_measurementdynamite@16089051@16.0.89 (040408-239467275):145) 
        at cf.a(:com.google.android.gms.dynamite_measurementdynamite@16089051@16.0.89 (040408-239467275):160) 
        at k.onTransact(:com.google.android.gms.dynamite_measurementdynamite@16089051@16.0.89 (040408-239467275):4) 
        at android.os.Binder.transact(Binder.java:499) 
        at com.google.android.gms.internal.measurement.zzq.zza(Unknown Source) 
        at com.google.android.gms.internal.measurement.zzdp.onActivityCreated(Unknown Source) 
        at com.google.android.gms.internal.measurement.zzex.zzgd(Unknown Source) 
        at com.google.android.gms.internal.measurement.zzea$zzb.run(Unknown Source) 
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133) 
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607) 
        at java.lang.Thread.run(Thread.java:760) 
     Caused by: java.lang.NoClassDefFoundError: Class not found using the boot class loader; no stack trace available

我的MainActivity.java是

public class MainActivity extends AppCompatActivity {
    final Fragment[] fragments = new Fragment[3];
    BottomNavigationView navView;
    FragmentManager fragmentManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        MobileAds.initialize(this, "ca-app-pub-3940256099942544~3347511713");

        fragmentManager = getSupportFragmentManager();

        Toolbar toolbar = findViewById(R.id.toolbar);
        toolbar.setTitle(getString(R.string.app_name));
        toolbar.setTitleTextColor(Color.WHITE);
        toolbar.setNavigationIcon(R.drawable.ic_navigation);



        navView = findViewById(R.id.nav_view);


        AdView adView = findViewById(R.id.adView);
        adView.loadAd(new AdRequest.Builder().build());


        fragments[0] = new RandomFragment();
        fragments[1] = new FullListFragment();
        fragments[2] = new FavoriteFragment();

        fragmentManager.beginTransaction().add(R.id.main_container2, fragments[0]).commit();


        navView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {

            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
                Fragment fragment;

                switch (menuItem.getItemId()) {
                    case R.id.navigation_home:
                        fragment = fragments[0];
                        break;

                    case R.id.navigation_dashboard:
                        fragment = fragments[1];
                        break;


                    case R.id.navigation_notifications:
                        fragment = fragments[2];
                        break;

                    default:
                        fragment = fragments[0];
                        break;
                }
                fragmentManager.beginTransaction().replace(R.id.main_container2, fragment).commit();
                return true;
            }
        });
        navView.setSelectedItemId(R.id.navigation_home);
    }


    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);

        outState.putInt("SelectedItemId", navView.getSelectedItemId());

    }


    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);
        int selectedItemId = savedInstanceState.getInt("SelectedItemId");
        navView.setSelectedItemId(selectedItemId);
    }


}

Answer 1

旋轉后，您的SupportMapFragment被銷毀並重新創建。 在銷毀它之前，它將其當前狀態寫入一個宗地，以便在重新創建時恢復其狀態。 Fragment的保存狀態將包括其子視圖的狀態，並且由於您已在其中嵌套了AdMob視圖 ，因此它也會嘗試保存和還原該視圖 。 AdMob沒有為此所需的內部類SavedState，因此，當嘗試從Parcel還原AdMob實例時，此過程將失敗。

解決方案是不要在該元素內嵌套AdMob或任何其他視圖。

這是您可以做的，就像黑客一樣

@Override
public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);

    AdView adView = (AdView)findViewById(R.id.adView);
    View contentFrame = findViewById(R.id.contentFrameLayout);

    RelativeLayout parent = (RelativeLayout) adView.getParent();
    LayoutParams mapFrameParams = contentFrame.getLayoutParams();
    LayoutParams adViewParams = adView.getLayoutParams();

    parent.removeView(adView);
    parent.removeView(contentFrame);

    AdView newAdView = new AdView(this, AdSize.SMART_BANNER, getString(R.string.admob_pubId));

    newAdView.setId(R.id.adView);

    parent.addView(newAdView, adViewParams);
    parent.addView(contentFrame,mapFrameParams);
    newAdView.loadAd(new AdRequest());
}

Answer 2

經過最長的思考。 我有答案。 在新庫中，添加了具有應用程序ID的ads初始化方法的witch沒有內部類SavedState。 因此，所有需要的都是像這樣保存appid：

private static final String APP_ID = "your_app_id"

 @Override
    protected void onCreate(Bundle savedInstanceState) {
Bundle adsInstanceState = (savedInstanceState != null)
                ? savedInstanceState.getBundle(APP_ID): null;
        super.onCreate(adsInstanceState);
MobileAds.initialize(this,APP_ID);
}

  @Override
    protected void onSaveInstanceState(@NonNull Bundle outState) {
        super.onSaveInstanceState(outState);
        Bundle adsInstanceState = new Bundle();
        outState.putBundle(APP_ID, adsInstanceState )
   }

類似的問題，但有地圖： https : //stackoverflow.com/a/36818004/11334749希望對某人有幫助