https://github.com/hmkcode/Android

Auto-increment versionCode using Gradle: https://medium.com/prathanbomb/tips-auto-increment-versioncode-of-android-using-gradle-dba0425af97c

How to Make a Camera App in Android Studio: https://jerrybanfield.com/make-camera-app-android-studio/

Android – Sending Email: https://www.tutorialspoint.com/android/android_sending_email.htm

Examples of Android applications: https://github.com/novoda/android-demos