Android Java Skill --- Project Structure --- Gradle Configuration App-level build.gradle --- Architecture Patterns MVVM with ViewModel Repository Pattern --- Activity & Fragment Patterns Activity with ViewBinding Fragment with ViewBinding --- Testing Unit Tests with JUnit & Mockito Instrumentation Tests with Espresso --- GitHub Actions --- Lint Configuration lint.xml build.gradle lint options --- Common Patterns Null-Safe Callbacks Safe Context Usage Thread-Safe Singleton --- Android Anti-Patterns - ❌ Context leaks - Never hold Activity/Fragment references in static fields or singletons - ❌ M…