NoClassDefFoundError: com.google.zxing.ResultMetadataType用于zxing

Question

我正在开发一个应用程序，通过ZXing扫描安卓上的条形码。我跟着这个教程。

但是当我运行我的应用程序时，NoClassDefFoundError得到并完成了应用程序。

08-06 10:42:43.401: E/AndroidRuntime(10391): FATAL EXCEPTION: main
08-06 10:42:43.401: E/AndroidRuntime(10391): Process: com.foxconn.cnsbg.it.barcodescanner, PID: 10391
08-06 10:42:43.401: E/AndroidRuntime(10391): java.lang.NoClassDefFoundError: Failed resolution of: Lcom/google/zxing/ResultMetadataType;
08-06 10:42:43.401: E/AndroidRuntime(10391):    at com.google.zxing.client.android.CaptureActivity.<clinit>(CaptureActivity.java:93)
08-06 10:42:43.401: E/AndroidRuntime(10391):    at java.lang.reflect.Constructor.newInstance(Native Method)
08-06 10:42:43.401: E/AndroidRuntime(10391):    at java.lang.Class.newInstance(Class.java:1572)
08-06 10:42:43.401: E/AndroidRuntime(10391):    at android.app.Instrumentation.newActivity(Instrumentation.java:1065)
08-06 10:42:43.401: E/AndroidRuntime(10391):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2246)
08-06 10:42:43.401: E/AndroidRuntime(10391):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2405)
08-06 10:42:43.401: E/AndroidRuntime(10391):    at android.app.ActivityThread.access$800(ActivityThread.java:149)
08-06 10:42:43.401: E/AndroidRuntime(10391):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1324)
08-06 10:42:43.401: E/AndroidRuntime(10391):    at android.os.Handler.dispatchMessage(Handler.java:102)
08-06 10:42:43.401: E/AndroidRuntime(10391):    at android.os.Looper.loop(Looper.java:211)
08-06 10:42:43.401: E/AndroidRuntime(10391):    at android.app.ActivityThread.main(ActivityThread.java:5333)
08-06 10:42:43.401: E/AndroidRuntime(10391):    at java.lang.reflect.Method.invoke(Native Method)
08-06 10:42:43.401: E/AndroidRuntime(10391):    at java.lang.reflect.Method.invoke(Method.java:372)
08-06 10:42:43.401: E/AndroidRuntime(10391):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1016)
08-06 10:42:43.401: E/AndroidRuntime(10391):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:811)
08-06 10:42:43.401: E/AndroidRuntime(10391): Caused by: java.lang.ClassNotFoundException: Didn't find class "com.google.zxing.ResultMetadataType" on path: DexPathList[[zip file "/data/app/com.foxconn.cnsbg.it.barcodescanner-2/base.apk"],nativeLibraryDirectories=[/vendor/lib, /system/lib]]
08-06 10:42:43.401: E/AndroidRuntime(10391):    at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
08-06 10:42:43.401: E/AndroidRuntime(10391):    at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
08-06 10:42:43.401: E/AndroidRuntime(10391):    at java.lang.ClassLoader.loadClass(ClassLoader.java:469)
08-06 10:42:43.401: E/AndroidRuntime(10391):    ... 15 more
08-06 10:42:43.401: E/AndroidRuntime(10391):    Suppressed: java.lang.ClassNotFoundException: com.google.zxing.ResultMetadataType
08-06 10:42:43.401: E/AndroidRuntime(10391):        at java.lang.Class.classForName(Native Method)
08-06 10:42:43.401: E/AndroidRuntime(10391):        at java.lang.BootClassLoader.findClass(ClassLoader.java:781)
08-06 10:42:43.401: E/AndroidRuntime(10391):        at java.lang.BootClassLoader.loadClass(ClassLoader.java:841)
08-06 10:42:43.401: E/AndroidRuntime(10391):        at java.lang.ClassLoader.loadClass(ClassLoader.java:504)
08-06 10:42:43.401: E/AndroidRuntime(10391):        ... 16 more
08-06 10:42:43.401: E/AndroidRuntime(10391):    Caused by: java.lang.NoClassDefFoundError: Class not found using the boot class loader; no stack available

我搜索了Google并在CaptureActivity项目中修复了构建路径，比如：

​

还将core-2.2.jar添加到库文件夹中，这两个文件夹都是CaptureActivity项目和my项目。我该如何解决这个问题？

Answer 1

看看这篇文章：升级sdk获得了NoClassDefFoundError

引用Till

“我不必将jar库放在资产或lib中，而只需在Properties -> Java构建路径-> "Order and Export”(以前列出，但未选中)中为该jar勾选

您可能需要做一个项目>清理之后，才能生效！“

这对我有用！

Answer 2

当您的代码所依赖的类文件在编译时存在，但在运行时没有找到时，NoClassDefFoundError就会发生。

由于core-2.2.jar中存在的类是应用程序的基础，为了保持一致性，您希望将此依赖项添加到lib文件夹中，而不是将其外部提供给构建路径。

还检查构建时间和运行时classpath的差异。对此进行快速检查可以解决你的问题。