Question

我试图用媒体播放器运行程序为什么我得到这个例外？请帮忙。

java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.android.myplayer/com.andr
oid.myplayer.MediaPlayerDemo_video}: java.lang.ClassNotFoundException: com.android.myplayer.MediaPlayerDemo_video in loader dal
vik.system.PathClassLoader@349c48d8
E/AndroidRuntime( 4102):        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2417)
E/AndroidRuntime( 4102):        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512)
E/AndroidRuntime( 4102):        at android.app.ActivityThread.access$2200(ActivityThread.java:119)
E/AndroidRuntime( 4102):        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863)
E/AndroidRuntime( 4102):        at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime( 4102):        at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime( 4102):        at android.app.ActivityThread.main(ActivityThread.java:4363)
E/AndroidRuntime( 4102):        at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime( 4102):        at java.lang.reflect.Method.invoke(Method.java:521)
E/AndroidRuntime( 4102):        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
E/AndroidRuntime( 4102):        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
E/AndroidRuntime( 4102):        at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime( 4102): Caused by: java.lang.ClassNotFoundException: com.android.myplayer.MediaPlayerDemo_video in loader dalv
ik.system.PathClassLoader@349c48d8
E/AndroidRuntime( 4102):        at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:243)
E/AndroidRuntime( 4102):        at java.lang.ClassLoader.loadClass(ClassLoader.java:573)
E/AndroidRuntime( 4102):        at java.lang.ClassLoader.loadClass(ClassLoader.java:532)
E/AndroidRuntime( 4102):        at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
E/AndroidRuntime( 4102):        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2409)
E/AndroidRuntime( 4102):        ... 11 more

Answer 1

该异常通常意味着CLASSPATH问题：当JVM需要加载它时，类加载器还没有被告知在哪里找到该类。因此，您需要确定哪个JAR包含该类并将其添加到CLASSPATH。

为什么尝试使用mediaplayer时会出现java.lang.ClassNotFoundException？

1 个答案: