运行适用于Android的YouTube API演示时未找到类别

最近,我无法运行任何适用于 Android的YouTube API演示版.
在实现与YouTube API类有一定依赖关系的第一个活动时,我得到一个ClassnotFoundException.
任何使用YouTube API的应用都会发生这种情况.

我的YouTube应用已更新至4.5.,我在三星Galaxy s3 mini上运行jellyBean.

我的手机或Eclipse中是否有任何设置可以丢失？

[编辑]
这是logcat副本(这次在Nexus S上运行)：

06-18 09:45:26.796: D/libEGL(15140): loaded /vendor/lib/egl/libEGL_POWERVR_SGX540_120.so
06-18 09:45:26.832: D/libEGL(15140): loaded /vendor/lib/egl/libGLESv1_CM_POWERVR_SGX540_120.so
06-18 09:45:26.836: D/libEGL(15140): loaded /vendor/lib/egl/libGLESv2_POWERVR_SGX540_120.so
06-18 09:45:26.964: D/OpenGLRenderer(15140): Enabling debug mode 0
06-18 09:45:35.796: W/dalvikvm(15140): Unable to resolve superclass of Lcom/examples/youtubeapidemo/YouTubeFailureRecoveryActivity; (109)
06-18 09:45:35.796: W/dalvikvm(15140): Link of class 'Lcom/examples/youtubeapidemo/YouTubeFailureRecoveryActivity;' Failed
06-18 09:45:35.804: W/dalvikvm(15140): Unable to resolve superclass of Lcom/examples/youtubeapidemo/PlayerViewDemoActivity; (102)
06-18 09:45:35.804: W/dalvikvm(15140): Link of class 'Lcom/examples/youtubeapidemo/PlayerViewDemoActivity;' Failed
06-18 09:45:35.820: D/AndroidRuntime(15140): ShutTing down VM
06-18 09:45:35.820: W/dalvikvm(15140): threadid=1: thread exiTing with uncaught exception (group=0x41a1a300)
06-18 09:45:35.855: E/AndroidRuntime(15140): FATAL EXCEPTION: main
06-18 09:45:35.855: E/AndroidRuntime(15140): java.lang.RuntimeException: Unable to instantiate activity ComponenTinfo{Com.examples.youtubeapidemo/com.examples.youtubeapidemo.PlayerViewDemoActivity}: java.lang.ClassnotFoundException: com.examples.youtubeapidemo.PlayerViewDemoActivity
06-18 09:45:35.855: E/AndroidRuntime(15140):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1983)
06-18 09:45:35.855: E/AndroidRuntime(15140):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
06-18 09:45:35.855: E/AndroidRuntime(15140):    at android.app.ActivityThread.access$600(ActivityThread.java:130)
06-18 09:45:35.855: E/AndroidRuntime(15140):    at android.app.ActivityThread$H.handlemessage(ActivityThread.java:1195)
06-18 09:45:35.855: E/AndroidRuntime(15140):    at android.os.Handler.dispatchmessage(Handler.java:99)
06-18 09:45:35.855: E/AndroidRuntime(15140):    at android.os.Looper.loop(Looper.java:137)
06-18 09:45:35.855: E/AndroidRuntime(15140):    at android.app.ActivityThread.main(ActivityThread.java:4745)
06-18 09:45:35.855: E/AndroidRuntime(15140):    at java.lang.reflect.Method.invokeNative(Native Method)
06-18 09:45:35.855: E/AndroidRuntime(15140):    at java.lang.reflect.Method.invoke(Method.java:511)
06-18 09:45:35.855: E/AndroidRuntime(15140):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
06-18 09:45:35.855: E/AndroidRuntime(15140):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
06-18 09:45:35.855: E/AndroidRuntime(15140):    at dalvik.system.NativeStart.main(Native Method)
06-18 09:45:35.855: E/AndroidRuntime(15140): Caused by: java.lang.ClassnotFoundException: com.examples.youtubeapidemo.PlayerViewDemoActivity
06-18 09:45:35.855: E/AndroidRuntime(15140):    at dalvik.system.baseDexClassLoader.findClass(BaseDexClassLoader.java:61)
06-18 09:45:35.855: E/AndroidRuntime(15140):    at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
06-18 09:45:35.855: E/AndroidRuntime(15140):    at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
06-18 09:45:35.855: E/AndroidRuntime(15140):    at android.app.instrumentation.newActivity(instrumentation.java:1053)
06-18 09:45:35.855: E/AndroidRuntime(15140):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1974)
06-18 09:45:35.855: E/AndroidRuntime(15140):    ... 11 more

[解决了！]

很酷我找到了答案.似乎是ADT后期更新中的一个错误.此链接解释了所有内容：https://groups.google.com/d/msg/adt-dev/epOfZbKPFdk/v4a-pTbq1OwJ

或者引用它：

项目右键单击>属性> Java构建路径>订单和出口>检查Android私有库>好

然后项目>清洁…

并重建/运行.