为什么我出现此错误？它只发生在android 4.4.2（api 19）或更低版本。
以前没有这个错误，但现在它发生了很多次。
Exception java.lang.NoClassDefFoundError: rt
rs.<clinit> (SourceFile:17)
android.support.v7.widget.RecyclerView.onSaveInstanceState (SourceFile:201)
android.view.View.dispatchSaveInstanceState (View.java:12895)
android.view.ViewGroup.dispatchFreezeSelfOnly (ViewGroup.java:2748)
android.support.v7.widget.RecyclerView.dispatchSaveInstanceState (SourceFile:220)
android.view.ViewGroup.dispatchSaveInstanceState (ViewGroup.java:2734)
android.view.ViewGroup.dispatchSaveInstanceState (ViewGroup.java:2734)
android.view.ViewGroup.dispatchSaveInstanceState (ViewGroup.java:2734)
android.view.ViewGroup.dispatchSaveInstanceState (ViewGroup.java:2734)
android.view.ViewGroup.dispatchSaveInstanceState (ViewGroup.java:2734)
android.view.View.saveHierarchyState (View.java:12878)
android.support.v4.app.FragmentManagerImpl.saveFragmentViewState (FragmentManager.java:2646)
android.support.v4.app.FragmentManagerImpl.moveToState (FragmentManager.java:1407)
android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState (FragmentManager.java:1574)
android.support.v4.app.FragmentManagerImpl.moveToState (FragmentManager.java:1641)
android.support.v4.app.FragmentManagerImpl.dispatchDestroyView (FragmentManager.java:3002)
android.support.v4.app.Fragment.performDestroyView (Fragment.java:2461)
android.support.v4.app.FragmentManagerImpl.moveToState (FragmentManager.java:1410)
android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState (FragmentManager.java:1574)
android.support.v4.app.BackStackRecord.executeOps (BackStackRecord.java:789)
android.support.v4.app.FragmentManagerImpl.executeOps (FragmentManager.java:2415)
android.support.v4.app.FragmentManagerImpl.executeOpsTogether (FragmentManager.java:2200)
android.support.v4.app.FragmentManagerImpl.optimizeAndExecuteOps (FragmentManager.java:2153)
android.support.v4.app.FragmentManagerImpl.execPendingActions (FragmentManager.java:2063)
android.support.v4.app.FragmentManagerImpl$1.run (FragmentManager.java:725)
android.os.Handler.handleCallback (Handler.java:808)
android.os.Handler.dispatchMessage (Handler.java:103)
android.os.Looper.loop (Looper.java:193)
android.app.ActivityThread.main (ActivityThread.java:5312)
java.lang.reflect.Method.invokeNative (Method.java)
java.lang.reflect.Method.invoke (Method.java:515)
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run (ZygoteInit.java:825)
com.android.internal.os.ZygoteInit.main (ZygoteInit.java:641)
dalvik.system.NativeStart.main (NativeStart.java)