Android Development Terms for Beginners

Core Android Terms:
Activity
- A single screen with UI.
- Has a lifecycle: onCreate, onStart, onResume.
- Declared in AndroidManifest.xml.

Fragment
- A reusable piece of UI inside an Activity.
- Has its own lifecycle.
- Ideal for tablets and modular screens.

Intent
- Explicit: targets a specific component (e.g., open DetailActivity).
- Implicit: describes an action (e.g., open a URL).

Context
- Gives access to resources, databases, and system services.
- Activity, Service, and Application all extend Context.

Activity Lifecycle Quick Notes:
onCreate()   — UI initialized once.
onStart()    — Activity becomes visible.
onResume()   — Activity is in the foreground.
onPause()    — Another activity comes in front.
onStop()     — Activity no longer visible.
onDestroy()  — Activity is destroyed.

Remember:
- Avoid heavy work in onCreate.
- Release resources in onStop/onDestroy.
- Use ViewModel to survive configuration changes.

UI & Layout Terms:
View
- The base class for all UI widgets.
- Examples: TextView, Button, ImageView.

ViewGroup
- Extends View and contains other Views.
- Examples: LinearLayout, ConstraintLayout, FrameLayout.

XML Layout
- Describes the UI in res/layout/*.xml.
- Easily previewed in Android Studio.

RecyclerView
- Reuses views as you scroll.
- Uses an Adapter to bind data.

Layout Choice Notes:
LinearLayout
- Stacks children horizontally or vertically.
- Simple and predictable.

ConstraintLayout
- Positions views relative to each other.
- Best for complex, flat hierarchies.

FrameLayout
- Stacks children on top of each other.
- Useful for overlays.

Guidelines:
- Keep layouts shallow.
- Avoid deep nesting for performance.
- Use ConstraintLayout for complex screens.

Advanced Android Terms:
ViewModel
- Holds UI-related data.
- Survives configuration changes.
- Part of Android Jetpack.

LiveData
- Lifecycle-aware observable.
- Automatically updates active observers.
- Prevents memory leaks.

Coroutines
- Suspend functions run without blocking threads.
- Use viewModelScope for UI work.
- Simplifies async code.

Gradle
- Declares dependencies in build.gradle.
- Runs tasks: build, install, test.
- Supports flavors and build types.

Gradle Quick Notes:
dependencies {
  implementation "androidx.core:core-ktx:..."
  implementation "androidx.appcompat:appcompat:..."
  implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:..."
}

Tasks:
./gradlew assembleDebug
./gradlew installDebug
./gradlew test

Tips:
- Keep dependency versions aligned.
- Use Gradle version catalogs.
- Sync often in Android Studio.

Core Glossary:
Activity      — A single screen with UI.
Fragment      — Reusable UI inside an Activity.
Intent        — Message to trigger an action.
Context       — Access to app environment.
Manifest      — Declares components and permissions.
APK           — Installable Android package.
AVD           — Android Virtual Device (emulator).

UI Glossary:
View          — Basic UI element.
ViewGroup     — Container of Views.
XML Layout    — Declarative UI file.
RecyclerView  — Efficient scrollable list.
ConstraintLayout — Flexible positioning layout.
Adapter       — Binds data to list items.
Drawable      — Image or shape resource.

Advanced Glossary:
ViewModel     — UI data across config changes.
LiveData      — Observable, lifecycle-aware data.
Coroutines    — Kotlin async tool.
Gradle        — Build system.
Room          — Local database library.
Retrofit      — HTTP client library.
Compose       — Declarative UI toolkit.