工具问题——再次手贱，报：java.lang.RuntimeException: Unable to instantiate activity ComponentInfo

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java.lang.RuntimeException: Unable to instantiate activity ComponentInfo

Project -> Properties ->java build path-> Order & Export 选上Private 然后clean 所有项目

06-13 13:31:52.925: D/AndroidRuntime(15684): Shutting down VM
06-13 13:31:52.925: W/dalvikvm(15684): threadid=1: thread exiting with uncaught exception (group=0x40db5300)
06-13 13:31:52.930: E/AndroidRuntime(15684): FATAL EXCEPTION: main
06-13 13:31:52.930: E/AndroidRuntime(15684): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.viewpagerdemo/com.example.viewpagerdemo.MainActivity}: java.lang.ClassNotFoundException: com.example.viewpagerdemo.MainActivity
06-13 13:31:52.930: E/AndroidRuntime(15684): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2034)
06-13 13:31:52.930: E/AndroidRuntime(15684): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2135)
06-13 13:31:52.930: E/AndroidRuntime(15684): at android.app.ActivityThread.access$700(ActivityThread.java:131)
06-13 13:31:52.930: E/AndroidRuntime(15684): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1228)
06-13 13:31:52.930: E/AndroidRuntime(15684): at android.os.Handler.dispatchMessage(Handler.java:99)
06-13 13:31:52.930: E/AndroidRuntime(15684): at android.os.Looper.loop(Looper.java:137)
06-13 13:31:52.930: E/AndroidRuntime(15684): at android.app.ActivityThread.main(ActivityThread.java:4866)
06-13 13:31:52.930: E/AndroidRuntime(15684): at java.lang.reflect.Method.invokeNative(Native Method)
06-13 13:31:52.930: E/AndroidRuntime(15684): at java.lang.reflect.Method.invoke(Method.java:511)
06-13 13:31:52.930: E/AndroidRuntime(15684): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
06-13 13:31:52.930: E/AndroidRuntime(15684): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
06-13 13:31:52.930: E/AndroidRuntime(15684): at dalvik.system.NativeStart.main(Native Method)
06-13 13:31:52.930: E/AndroidRuntime(15684): Caused by: java.lang.ClassNotFoundException: com.example.viewpagerdemo.MainActivity
06-13 13:31:52.930: E/AndroidRuntime(15684): at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61)
06-13 13:31:52.930: E/AndroidRuntime(15684): at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
06-13 13:31:52.930: E/AndroidRuntime(15684): at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
06-13 13:31:52.930: E/AndroidRuntime(15684): at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
06-13 13:31:52.930: E/AndroidRuntime(15684): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2025)
06-13 13:31:52.930: E/AndroidRuntime(15684): ... 11 more

http://stackoverflow.com/questions/16610190/classnotfoundexception-after-adt-update

http://stackoverflow.com/questions/16610296/android-unable-to-instantiate-activity-class-not-found-exception-after-upgra