Android 修改Project文件夹名称，引起的错误

 FATAL EXCEPTION: main

Process: com.example.q.mydialog, PID: 12677

java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.q.mydialog/com.example.q.mydialog.MainActivity}: java.lang.ClassNotFoundException: Didn't find class "com.example.q.mydialog.MainActivity" on path: DexPathList[[zip file "/data/app/com.example.q.mydialog-1/base.apk"],nativeLibraryDirectories=[/data/app/com.example.q.mydialog-1/lib/x86, /system/lib, /vendor/lib]]

菜单Build ---> clean project

Build ---> rebuild project

再删除app 的 build文件夹，和project的build 文件夹