我的android studio 无法预览xml文件

老师， 我的android studio 无法预览xml文件； 刷新了也不行！ 

Failed to load AppCompat ActionBar with unknown error.   Tip: Try to refresh the layout.

The following classes could not be instantiated:

- android.support.v7.widget.ActionBarContainer (Open Class, Show Exception, Clear Cache)

- android.support.v7.widget.ActionBarContextView (Open Class, Show Exception, Clear Cache)

- android.support.v7.app.WindowDecorActionBar (Open Class, Show Exception, Clear Cache)

 Tip: Use View.isInEditMode() in your custom views to skip code or show sample data when shown in the IDE.  If this is an unexpected error you can also try to build the project, then manually refresh the layout.  Exception Details java.lang.ClassNotFoundException: android.view.View$OnUnhandledKeyEventListener Copy stack to clipboard