java.lang.RuntimeException: Unable to instantiate activity ComponentInfo / java.lang.ClassNotFoundException

Question

I'm having this error while running on my device. I've been browsing the issue and I'm pretty sure I'm not having the same issues as mentioned. Both of my activities are declared in the AndroidManifest and the intent filter is there. I have no libraries whatsoever (except v4 support library, but declaring it doesn't change the problem). I tried replacing in my Manifest carpedujourproductions.quickpronote.MainActivity by .MainActivity but still no luck. I'm running Android Studio 0.2.5 so I couldn't find how to resolve potential issues related to Java Build Path/Order and Export

I couldn't help but noticing my MainActivity's icon in the tree had a grey cross on the upper-left corner.

Logcat:

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"],nativeLibraryDirectories=[/data/app-lib/carpedujourproductions.quickpronote-2, /vendor/lib, /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

Feel free to browse through the code here for AndroidManifest, MainActivity.java, FirstRun.java, etc.

Answer 1

Your MainActivity.java is excluded from compile, so this class isn't included in .apk. Remove line:

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

from the excludeFromCompile section of the .idea/compiler.xml file (or you can do this from IDE settings).