Unexplainable ClassCastException in android.widget

问题:

I've had my application out in the store for a while, but it seems it crashes occasionally according to the crash reports in the Developer Console, saying: java.lang.ClassCastException in android.widget.ProgressBar.onRestoreInstanceState with the stack trace:

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.company.myapp/com.mycompany.myapp.activity.MyActivity}: java.lang.ClassCastException: android.view.AbsSavedState$1 cannot be cast to android.widget.ProgressBar$SavedState
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1996)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2023)
at android.app.ActivityThread.access$600(ActivityThread.java:127)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1174)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4503)
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:809)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:576)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ClassCastException: android.view.AbsSavedState$1 cannot be cast to android.widget.ProgressBar$SavedState
at android.widget.ProgressBar.onRestoreInstanceState(ProgressBar.java:1093)
at android.view.View.dispatchRestoreInstanceState(View.java:9975)
at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:2408)
at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:2408)
at android.view.View.restoreHierarchyState(View.java:9951)
at com.android.internal.policy.impl.PhoneWindow.restoreHierarchyState(PhoneWindow.java:1611)
at android.app.Activity.onRestoreInstanceState(Activity.java:908)
at android.app.Activity.performRestoreInstanceState(Activity.java:880)
at android.app.Instrumentation.callActivityOnRestoreInstanceState(Instrumentation.java:1102)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1974)
... 11 more

The reason for these crashes eludes me, and I can't reproduce it on any of my devices. I don't have a onRestoreInstanceState overridden anywhere either. Can anyone point me in a direction that makes sense?

回答1:

I've seen similar issues to this before, and it's because you have two id's that share the same name.

The onRestoreInstanceState has performed the findViewById method and the first view to be found was not the ProgressView.

Double check that your application does not reuse the same ID in two different places

回答2:

I had a different issue: In one layout the root was a ScrollView while in the other the root was a RelativeView that contained the ScrollView. All widgets ids were identical and there were no duplicates. On rotate the crash log was:

java.lang.ClassCastException: android.view.AbsSavedState$1 cannot be cast to android.widget.ScrollView$SavedState

Once I matched the layouts (so in both the root was either the RelativeLayout or ScrollView), the rotation worked fine.

Not sure why this would cause a crash so any insights would be appreciated...

回答3:

In my case my portrait xml has Relativelayout and ScrollView from landscape xml with the same ID.

On my activity class I try to inflate the layout and assign it on ViewGroup

So when screen rotation occur it throws: java.lang.ClassCastException: android.view.AbsSavedState$1 cannot be cast to android.widget.ScrollView$SavedState

It's because the ScrollView extends FrameLayout while Relativelayout extends ViewGroup

So i just wrap the landscape xml with Relativelayout and solves the problem

回答4:

I got this crash messsage on rotation when I had a GridView in two different layouts, one portrait and the other landscape. One was contained in a FrameLayout and the other was not, i.e., it was by itself in the layout file. When I removed the wrapping FrameLayout, everything worked fine. (Note: the GridView was used on the master side of a master/view layout.)

The message did not appear until I upgraded my Gradle settings to this:

android {
    compileSdkVersion 23
    buildToolsVersion '23.0.2'
    defaultConfig {
        applicationId 'com.example.android.redacted.app'
        minSdkVersion 16
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }  

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    compile 'com.android.support:appcompat-v7:23.1.1'

}

They were previously this:

android {
    compileSdkVersion 21
    buildToolsVersion '21.1.2'
    defaultConfig {
        applicationId 'com.example.android.redacted.app'
        minSdkVersion 11
        targetSdkVersion 21
        versionCode 1
        versionName "1.0"
    }


dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    compile 'com.android.support:appcompat-v7:21.0.2'
}

It seems Marshmallow is more unforgiving with this bug.