Jetpack Compose basics

Jetpack Compose simplifies and accelerates Android UI development with less code and intuitive Kotlin APIs, building UI with declarative functions instead of XML layouts. Add the @Composable annotation to make a function composable; composable functions can only be called from other composable functions, and the setContent block defines the activity's layout where they are called. A Kotlin compiler plugin transforms composable functions into the app's UI elements. Compose is built to support Material Design principles; wrap composables in the project's theme (found in the ui.theme subpackage) and Surface to style them. The tutorial uses dynamic theming colors defined by device preferences; set dynamicColor to false in MaterialTheme.kt to change this. Style Text with MaterialTheme.colorScheme.secondary and border Images via Modifier.border with colors and shapes. Scope: Android Kotlin. Reviewed October 4, 2026.