Android Development Fundamentals
Android is the most widely used mobile OS. Development uses Android Studio with Java or Kotlin.
Architecture
Linux kernel, HAL, native libraries, Android Runtime (ART), Java API Framework, apps. Sandboxed with permissions.
Activities and Lifecycle
Activity = single screen. Callbacks: onCreate, onStart, onResume, onPause, onStop, onDestroy. Critical for resource management.
Layouts and UI
XML layouts: LinearLayout, RelativeLayout, ConstraintLayout (recommended). Widgets: TextView, Button, EditText, ImageView, RecyclerView.
Intents
Messaging objects. Explicit (specific component) and implicit (system handles). Data passed via extras.
Resources
Strings, colours, drawables in res/ directory. Qualifiers for screen sizes, languages, orientations.
Gradle
Build system managing dependencies, SDK versions, build types. Maven Central and Google repositories.
Summary
Android fundamentals: Activities, layouts, intents, resources, and Gradle build system.