The .APK file is then signed by the signing host (e.g.. GoogleSignatureCertificateSigner.CRT). As soon as the signing server has successfully validated the signing certificate against Google's certificate database. The .APK file is also signed by the certificate on Google's server. Once this process is completed the file is signed, compressed and stored in the application.APK. After a change to a code or application (e.g. adding new code into the application) Then the signer will have to be renewed. How do I create and modify Android library packages? — Stack Overflow Android Studio can create new libraries to the Android Studio. The only things you need to create libraries are: a .java source file a .jar source file the package name How do I sign a.class file? — Android Developers How do I build and publish an Android application? — Android Developers Android Studio can be used to build and package .APK files, and it can be useful to set up a release process to automatically push a new version of an application for download. You can use a combination of command line tools and a graphical IDE to control, debug, monitor and distribute a single instance of a given application. See the instructions on the Android Developers website for more information. — Stack Overflow How to deploy an Android application — Android Studio How to generate an APK build bundle, which contains all APK files, in Android Studio? As an example, if you're building an application in which you have an app entry point as well as a user interface, then you may need to do this: 1. Go to Build → Build Bundle. 2. Set the APK Bundle Generation to Use Default APK Bundle. 3. In the APK Bundle section, select All APK Files. 5. Click on the Add .APK file button. 6. Click on the Add .APK file .zip button. 7. Click on the Add .APK file .APK file (.APK) button. 8. Then your application should be built, signed and packaged. How do I generate an app package of my choice, which contains a Java file that you can publish to the Play store? We recommend having Java applications with at least one shared class file at project level (e.g. your own private Java library that is distributed with your application).