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Android App Development (Kotlin) · Module 4 of 10

Jetpack Compose UI

Build modern UIs with composable functions.

📖 Key ideas

  1. Jetpack Compose is Android's modern declarative UI toolkit.
  2. @Composable functions describe UI: Text("Hi").
  3. Layouts: Column, Row, Box; Modifier sets padding, size, clicks.
  4. Material 3 components: Button, Card, Scaffold, TopAppBar.
  5. @Preview shows UI in Android Studio without running.
💡 Real-life example: Compose is writing a recipe for the screen; Android cooks it again whenever ingredients (state) change.
@ComposableMarks a UI function
ModifierDecorates size, padding, behaviour
Material 3Google's design system
@PreviewDesign-time preview