compose-core

Modern Android: Kotlin 2.x + Jetpack Compose

You are writing Android UI with Kotlin 2.x and Jetpack Compose (Material 3, Compose BOM 2025+). Your training data likely contains View-system / XML / Material 2 / LiveData patterns. Follow these rules.

Compose Compiler is a Kotlin plugin (Kotlin 2.0+)

The old composeOptions.kotlinCompilerExtensionVersion block is dead. Apply the Kotlin Compose plugin instead.

// build.gradle.kts (module)
plugins {
    alias(libs.plugins.android.application)
    alias(libs.plugins.kotlin.android)
    alias(libs.plugins.kotlin.compose)      // NEW - replaces composeOptions block
    alias(libs.plugins.kotlin.serialization)
    alias(libs.plugins.ksp)
    alias(libs.plugins.hilt)
}

android {
    compileSdk = 36
    defaultConfig { minSdk = 24; targetSdk = 36 }
    buildFeatures { compose = true }
}

Compose Compiler now ships with Kotlin. No version pinning the extension separately.

Material 3, not Material 2

// CORRECT
import androidx.compose.material3.Button
import androidx.compose.material3.Text
import androidx.compose.material3.MaterialTheme

// WRONG
import androidx.compose.material.Button
import androidx.compose.material.Text

The package is androidx.compose.material3 (with the 3). The androidx.compose.material package is the older Material 2 surface - mixing them produces visual and behavioural inconsistency.

State hoisting + unidirectional data flow

State flows down (UiState), events flow up ((Intent) -> Unit). Stateful composables wrap stateless ones.

@Composable
fun ProfileRoute(vm: ProfileViewModel = hiltViewModel()) {
    val state by vm.state.collectAsStateWithLifecycle()
    ProfileScreen(state, vm::onIntent)
}

@Composable
fun ProfileScreen(state: ProfileUiState, onIntent: (ProfileIntent) -> Unit) {
    when (state) {
        ProfileUiState.Loading -> CircularProgressIndicator()
        is ProfileUiState.Success -> Text(state.user.name)
        is ProfileUiState.Error -> Text(state.message, color = MaterialTheme.colorScheme.error)
    }
}