java.lang.ClassNotFoundException

[locht710]

I did the tutorial to perform silent update app. But I get an error:
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.vivekpanyam.TestApp/com.example.MainActivity}: java.lang.ClassNotFoundException: Didn't find class "com.example.MainActivity" on path: DexPathList[[zip file "/data/app/com.vivekpanyam.TestApp-1/base.apk"],nativeLibraryDirectories=[/vendor/lib, /system/lib]]

I cannot find "base.apk" anywhere in source code. How can I fix this? You can provide me a more detail instruction to use this library? Thank you so much.