android – java.lang.RuntimeException：无法实例化活动ComponentInfo / java.lang.ClassNotFoundException

我在设备上运行时遇到此错误.我一直在浏览这个问题,我很确定我没有提到的问题.我的两个活动都在 AndroidManifest中声明,而intent过滤器就在那里.我没有任何库(除了v4支持库,但声明它不会改变问题).我尝试用.MainActivity替换我的Manifest carpedujourproductions.quickpronote.MainActivity,但仍然没有运气.我正在运行Android Studio 0.2.5,所以我找不到如何解决与Java Build Path / Order and Export相关的潜在问题

我忍不住注意到我的MainActivity图标在树的左上角有一个灰色的十字架.

logcat的：

E/AndroidRuntime: FATAL EXCEPTION: main
        java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{carpedujourproductions.quickpronote/carpedujourproductions.quickpronote.MainActivity}: java.lang.classNotFoundException: Didn't find class "carpedujourproductions.quickpronote.MainActivity" on path: DexPathList[[zip file "/data/app/carpedujourproductions.quickpronote-2.apk"],nativeLibraryDirectories=[/data/app-lib/carpedujourproductions.quickpronote-2,/vendor/lib,/system/lib]]
        at android.app.ActivityThread.performlaunchActivity(ActivityThread.java:2157)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2281)
        at android.app.ActivityThread.access$600(ActivityThread.java:148)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1263)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:5124)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:525)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
        at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:110)
        at dalvik.system.NativeStart.main(Native Method)
        Caused by: java.lang.classNotFoundException: Didn't find class "carpedujourproductions.quickpronote.MainActivity" on path: DexPathList[[zip file "/data/app/carpedujourproductions.quickpronote-2.apk"],/system/lib]]
        at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:53)
        at java.lang.classLoader.loadClass(ClassLoader.java:501)
        at java.lang.classLoader.loadClass(ClassLoader.java:461)
        at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
        at android.app.ActivityThread.performlaunchActivity(ActivityThread.java:2148)
        ... 12 more

随意浏览AndroidManifest,MainActivity.java,FirstRun.java等代码here.

解决方法

您的MainActivity.java被排除在编译之外,因此该类不包含在.apk中.删除行：

<file url="file://$PROJECT_DIR$/src/carpedujourproductions/quickpronote/MainActivity.java" />

来自.idea / compiler.xml文件的excludeFromCompile部分(或者您可以从IDE设置执行此操作).