java.lang.ClassNotFoundException：更新Android studio后没找到类（Local）

Question

自从我更新到21以来，我一直收到java.lang.ClassNotFoundException错误。

我的apk每次安装都会崩溃并抛出以下错误：

java.lang.RuntimeException: Unable to instantiate application mypackage.class:    
   java.lang.ClassNotFoundException: Didn't find class "mypackage.class" on path:  
            at android.app.LoadedApk.makeApplication(LoadedApk.java:507)
            at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4301)
            at android.app.ActivityThread.access$1500(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5001)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
            at dalvik.system.NativeStart.main(Native Method)

过去人们似乎遇到过类似的问题，这个解决方案对他们有用。

我使用的是android studio而不是Eclipse，所以我没有采取什么步骤来重现。

Libraries do not get added to APK anymore after upgrade to ADT 22