Android does not work after modifying the app code

Today, a problem has been encountered in the virtual machine to modify the code of an application, the compilation also passed. But it doesn't work on push-to-phone.

I later found that each app in the/system/app directory of my test machine corresponds to a xxx.odex file. It's just that you didn't have it.

Deleting the Xxx.odex file, causing itself to push the APK into the/system/app directory just replaced the original apk and did not execute, the system

The app's Xxx.odex file is also executed.

Remove Xxx.odex and push the apk on it.

Android does not work after modifying the app code