Start Building KMP App with Material Design 3 Expressive – 2025

Introduction: Transform Your Cross-Platform Development with Material Design 3

Are you ready to revolutionize your mobile development workflow? Building Kotlin Multiplatform (KMP) apps with Material Design 3 Expressive isn’t just a trend—it’s the future of efficient, beautiful cross-platform development. As an Android developer working with Kotlin, you’re perfectly positioned to leverage this powerful combination that delivers native performance with stunning, adaptive UIs across multiple platforms.

Material Design 3 represents Google’s most sophisticated design system yet, introducing expressive components, dynamic theming, and emotionally intelligent interfaces. When paired with KMP’s code-sharing capabilities, you can create applications that not only look exceptional but also maintain consistency across Android, iOS, and beyond while dramatically reducing development time.

Why Material Design 3 with KMP Matters for Android Developers Now

The mobile development landscape has shifted dramatically in 2024. Users expect seamless experiences across devices, while businesses demand faster delivery cycles and reduced development costs. Material Design 3 addresses these challenges by providing:

Revolutionary Design Capabilities

• Dynamic Color Systems: Automatically adapt to user wallpapers and preferences
• Expressive Typography: Variable fonts that scale beautifully across devices
• Emotionally Aware Components: UI elements that respond with natural motion and feedback
• Adaptive Layouts: Seamless transitions between phone, tablet, and foldable form factors

KMP Integration Benefits

• 70% Code Reusability: Share business logic, networking, and data layers
• Native Performance: Compile to platform-specific code for optimal speed
• Unified Development Experience: Single codebase for multiple platforms
• Reduced Time-to-Market: Deploy features simultaneously across platforms

Core Material Design 3 Principles for KMP Development

Successful KMP apps with Material Design 3 follow specific architectural and design principles that ensure maintainability, scalability, and visual excellence.

Principle 1: Shared Logic, Expressive UI Architecture

The foundation of effective KMP development lies in strategic code separation. Your shared module should contain:

<em>// Shared module structure</em>
commonMain/
├── data/
│   ├── models/
│   ├── repositories/
│   └── network/
├── domain/
│   ├── usecases/
│   └── entities/
└── presentation/
    ├── viewmodels/
    └── state/

Real-World Example: Consider a fitness tracking app. The WorkoutSession data class, FitnessRepository, and WorkoutAnalytics business logic reside in the shared module. The Android UI uses Jetpack Compose with Material Design 3 components, while iOS implements SwiftUI equivalents, both consuming the same shared logic.

Principle 2: Dynamic Theming and Adaptive Components

Material Design 3’s dynamic color system creates personalized experiences that adapt to user preferences and device capabilities. Implementation involves:

<em>// Android implementation with dynamic colors</em>
@Composable
fun AppTheme(
    darkTheme: Boolean = isSystemInDarkTheme(),
    dynamicColor: Boolean = true,
    content: @Composable () -> Unit
) {
    val colorScheme = when {
        dynamicColor && Build.VERSION.SDK_INT >= Build.VERSION_CODES.S -> {
            val context = LocalContext.current
            if (darkTheme) dynamicDarkColorScheme(context) 
            else dynamicLightColorScheme(context)
        }
        darkTheme -> DarkColorScheme
        else -> LightColorScheme
    }
    
    MaterialTheme(
        colorScheme = colorScheme,
        typography = AppTypography,
        content = content
    )
}

Principle 3: Emotionally Aware Design Implementation

Material Design 3 Expressive emphasizes emotional connection through:

• Natural Motion Patterns: Springy animations that feel organic
• Responsive Feedback: Components that react intuitively to user interaction
• Contextual Adaptations: UI elements that change based on user behavior and preferences

Case Study: A meditation app implemented Material Design 3’s emotional design principles by using soft, breathing animations for the main interface, bold confidence-building typography for achievement screens, and curious motion reveals for discovering new content. User engagement increased by 40% after implementation.

Principle 4: Cross-Platform Component Consistency

Maintaining design consistency across platforms while respecting platform conventions:

<em>// Shared component interface</em>
expect class PlatformButton {
    fun create(
        text: String,
        onClick: () -> Unit,
        style: ButtonStyle
    ): @Composable () -> Unit
}

<em>// Android implementation</em>
actual class PlatformButton {
    actual fun create(
        text: String,
        onClick: () -> Unit,
        style: ButtonStyle
    ): @Composable () -> Unit = {
        Button(
            onClick = onClick,
            colors = ButtonDefaults.buttonColors(
                containerColor = MaterialTheme.colorScheme.primary
            )
        ) {
            Text(text)
        }
    }
}

Comparison Table: Traditional vs Material Design 3 KMP Approach

Step-by-Step Implementation Guide

Let’s build a complete KMP app with Material Design 3 Expressive from scratch.

Step 1: Project Setup and Dependencies

<em>// build.gradle.kts (shared module)</em>
kotlin {
    androidTarget {
        compilations.all {
            kotlinOptions {
                jvmTarget = "1.8"
            }
        }
    }
    
    listOf(
        iosX64(),
        iosArm64(),
        iosSimulatorArm64()
    ).forEach {
        it.binaries.framework {
            baseName = "shared"
            isStatic = true
        }
    }

    sourceSets {
        commonMain.dependencies {
            implementation(compose.runtime)
            implementation(compose.foundation)
            implementation(compose.material3)
            implementation(compose.ui)
            implementation(compose.components.resources)
            implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.7.3")
            implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.6.0")
        }
        
        androidMain.dependencies {
            implementation("androidx.compose.ui:ui-tooling-preview:1.5.4")
            implementation("androidx.activity:activity-compose:1.8.1")
        }
    }
}

Step 2: Material Design 3 Theme Configuration

<em>// theme/Color.kt</em>
val md_theme_light_primary = Color(0xFF6750A4)
val md_theme_light_onPrimary = Color(0xFFFFFFFF)
val md_theme_light_primaryContainer = Color(0xFFEADDFF)
val md_theme_light_onPrimaryContainer = Color(0xFF21005D)

val md_theme_dark_primary = Color(0xFFD0BCFF)
val md_theme_dark_onPrimary = Color(0xFF381E72)
val md_theme_dark_primaryContainer = Color(0xFF4F378B)
val md_theme_dark_onPrimaryContainer = Color(0xFFEADDFF)

val LightColors = lightColorScheme(
    primary = md_theme_light_primary,
    onPrimary = md_theme_light_onPrimary,
    primaryContainer = md_theme_light_primaryContainer,
    onPrimaryContainer = md_theme_light_onPrimaryContainer,
    <em>// ... additional colors</em>
)

val DarkColors = darkColorScheme(
    primary = md_theme_dark_primary,
    onPrimary = md_theme_dark_onPrimary,
    primaryContainer = md_theme_dark_primaryContainer,
    onPrimaryContainer = md_theme_dark_onPrimaryContainer,
    <em>// ... additional colors</em>
)

Step 3: Expressive Typography Implementation

<em>// theme/Typography.kt</em>
val AppTypography = Typography(
    displayLarge = TextStyle(
        fontFamily = FontFamily.Default,
        fontWeight = FontWeight.Normal,
        fontSize = 57.sp,
        lineHeight = 64.sp,
        letterSpacing = (-0.25).sp,
    ),
    headlineLarge = TextStyle(
        fontFamily = FontFamily.Default,
        fontWeight = FontWeight.Bold,
        fontSize = 32.sp,
        lineHeight = 40.sp,
        letterSpacing = 0.sp,
    ),
    bodyLarge = TextStyle(
        fontFamily = FontFamily.Default,
        fontWeight = FontWeight.Normal,
        fontSize = 16.sp,
        lineHeight = 24.sp,
        letterSpacing = 0.5.sp,
    )
)

Step 4: Shared Business Logic

<em>// shared/domain/TaskRepository.kt</em>
class TaskRepository {
    private val tasks = mutableListOf<Task>()
    
    suspend fun getTasks(): List<Task> {
        delay(500) <em>// Simulate network call</em>
        return tasks.toList()
    }
    
    suspend fun addTask(task: Task) {
        tasks.add(task)
    }
    
    suspend fun updateTask(task: Task) {
        val index = tasks.indexOfFirst { it.id == task.id }
        if (index != -1) {
            tasks[index] = task
        }
    }
}

<em>// shared/presentation/TaskViewModel.kt</em>
class TaskViewModel {
    private val repository = TaskRepository()
    private val _uiState = MutableStateFlow(TaskUiState())
    val uiState: StateFlow<TaskUiState> = _uiState.asStateFlow()
    
    fun loadTasks() {
        viewModelScope.launch {
            _uiState.value = _uiState.value.copy(isLoading = true)
            try {
                val tasks = repository.getTasks()
                _uiState.value = _uiState.value.copy(
                    tasks = tasks,
                    isLoading = false
                )
            } catch (e: Exception) {
                _uiState.value = _uiState.value.copy(
                    error = e.message,
                    isLoading = false
                )
            }
        }
    }
}

Step 5: Android UI with Material Design 3

<em>// androidApp/MainActivity.kt</em>
@Composable
fun TaskScreen(viewModel: TaskViewModel) {
    val uiState by viewModel.uiState.collectAsState()
    
    LazyColumn(
        modifier = Modifier
            .fillMaxSize()
            .padding(16.dp),
        verticalArrangement = Arrangement.spacedBy(8.dp)
    ) {
        items(uiState.tasks) { task ->
            TaskCard(
                task = task,
                onTaskClick = { <em>/* Handle click */</em> },
                modifier = Modifier.animateItemPlacement()
            )
        }
    }
}

@Composable
fun TaskCard(
    task: Task,
    onTaskClick: () -> Unit,
    modifier: Modifier = Modifier
) {
    Card(
        modifier = modifier
            .fillMaxWidth()
            .clickable { onTaskClick() },
        elevation = CardDefaults.cardElevation(defaultElevation = 4.dp),
        colors = CardDefaults.cardColors(
            containerColor = MaterialTheme.colorScheme.surfaceVariant
        )
    ) {
        Column(
            modifier = Modifier.padding(16.dp)
        ) {
            Text(
                text = task.title,
                style = MaterialTheme.typography.headlineSmall,
                color = MaterialTheme.colorScheme.onSurfaceVariant
            )
            Spacer(modifier = Modifier.height(4.dp))
            Text(
                text = task.description,
                style = MaterialTheme.typography.bodyMedium,
                color = MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = 0.7f)
            )
        }
    }
}

Advanced Material Design 3 Features

Dynamic Color Implementation

@Composable
fun DynamicThemeExample() {
    val context = LocalContext.current
    val dynamicColorScheme = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
        dynamicLightColorScheme(context)
    } else {
        LightColors
    }
    
    MaterialTheme(
        colorScheme = dynamicColorScheme,
        typography = AppTypography
    ) {
        <em>// Your app content</em>
    }
}

Expressive Motion and Animation

@Composable
fun ExpressiveButton(
    text: String,
    onClick: () -> Unit,
    modifier: Modifier = Modifier
) {
    var isPressed by remember { mutableStateOf(false) }
    val scale by animateFloatAsState(
        targetValue = if (isPressed) 0.95f else 1f,
        animationSpec = spring(
            dampingRatio = Spring.DampingRatioMediumBouncy,
            stiffness = Spring.StiffnessLow
        )
    )
    
    Button(
        onClick = {
            onClick()
        },
        modifier = modifier
            .scale(scale)
            .pointerInput(Unit) {
                detectTapGestures(
                    onPress = {
                        isPressed = true
                        tryAwaitRelease()
                        isPressed = false
                    }
                )
            },
        colors = ButtonDefaults.buttonColors(
            containerColor = MaterialTheme.colorScheme.primary
        )
    ) {
        Text(
            text = text,
            style = MaterialTheme.typography.labelLarge
        )
    }
}

Testing and Quality Assurance

Unit Testing Shared Logic

<em>// shared/test/TaskRepositoryTest.kt</em>
class TaskRepositoryTest {
    private lateinit var repository: TaskRepository
    
    @BeforeTest
    fun setup() {
        repository = TaskRepository()
    }
    
    @Test
    fun `addTask should increase task count`() = runTest {
        val initialCount = repository.getTasks().size
        val newTask = Task("1", "Test Task", "Description")
        
        repository.addTask(newTask)
        
        val finalCount = repository.getTasks().size
        assertEquals(initialCount + 1, finalCount)
    }
}

UI Testing with Compose

<em>// androidApp/test/TaskScreenTest.kt</em>
@RunWith(AndroidJUnit4::class)
class TaskScreenTest {
    @get:Rule
    val composeTestRule = createComposeRule()
    
    @Test
    fun taskScreen_displaysTaskList() {
        val mockTasks = listOf(
            Task("1", "Task 1", "Description 1"),
            Task("2", "Task 2", "Description 2")
        )
        
        composeTestRule.setContent {
            AppTheme {
                TaskList(tasks = mockTasks)
            }
        }
        
        composeTestRule.onNodeWithText("Task 1").assertIsDisplayed()
        composeTestRule.onNodeWithText("Task 2").assertIsDisplayed()
    }
}

Performance Optimization Strategies

Lazy Loading and State Management

@Composable
fun OptimizedTaskList(
    tasks: List<Task>,
    modifier: Modifier = Modifier
) {
    LazyColumn(
        modifier = modifier,
        contentPadding = PaddingValues(16.dp),
        verticalArrangement = Arrangement.spacedBy(8.dp)
    ) {
        items(
            items = tasks,
            key = { task -> task.id }
        ) { task ->
            TaskCard(
                task = task,
                modifier = Modifier.animateItemPlacement(
                    animationSpec = tween(300)
                )
            )
        }
    }
}

Memory Management

class TaskViewModel : ViewModel() {
    private val _tasks = MutableStateFlow<List<Task>>(emptyList())
    val tasks: StateFlow<List<Task>> = _tasks.asStateFlow()
    
    override fun onCleared() {
        super.onCleared()
        <em>// Clean up resources</em>
    }
}

Future Trends and Predictions

The convergence of KMP and Material Design 3 is accelerating several key trends:

1. AI-Powered Adaptive Interfaces

Expect Material Design 3 to integrate machine learning capabilities that automatically adjust UI elements based on user behavior patterns and preferences.

2. Enhanced Cross-Platform Consistency

Compose Multiplatform will mature to provide near-identical UI experiences across all platforms while maintaining native performance.

3. WebAssembly Integration

KMP’s WebAssembly target will enable sharing business logic between mobile apps and high-performance web applications.

4. Extended Platform Support

KMP will expand to support emerging platforms including AR/VR devices, automotive systems, and IoT devices.

5. Advanced Motion Design

Material Design 3 will incorporate more sophisticated physics-based animations and haptic feedback integration.

Common Pitfalls and How to Avoid Them

1. Over-Sharing UI Code

Problem: Attempting to share too much UI logic across platforms.
Solution: Focus on sharing business logic, data models, and networking. Keep UI platform-specific for optimal user experience.

2. Ignoring Platform Conventions

Problem: Creating identical UIs that don’t feel native to each platform.
Solution: Adapt Material Design 3 principles to respect platform-specific navigation patterns and interaction models.

3. Performance Bottlenecks

Problem: Not optimizing shared code for mobile constraints.
Solution: Profile regularly, use appropriate data structures, and implement lazy loading where necessary.

Conclusion: Your Path to Expressive Cross-Platform Excellence

Building KMP apps with Material Design 3 Expressive represents the pinnacle of modern mobile development. By combining Kotlin’s powerful multiplatform capabilities with Google’s most advanced design system, you can create applications that are not only functionally superior but also emotionally engaging and visually stunning.

The implementation strategies, code examples, and best practices outlined in this guide provide you with a solid foundation to start building your own expressive multiplatform applications. Remember that successful KMP development is about finding the right balance between code sharing and platform-specific optimization.

As Material Design 3 continues to evolve and KMP matures, early adopters will have a significant competitive advantage. Start experimenting with these technologies today, and you’ll be well-positioned to deliver the next generation of mobile applications that users love and businesses depend on.

The future of mobile development is expressive, efficient, and truly multiplatform. Your journey starts now.

About the Author: A senior Android developer with 10+ years of experience in Kotlin and cross-platform development. Specializes in Material Design implementation, KMP architecture, and performance optimization. Passionate about creating beautiful, functional applications that push the boundaries of mobile technology.

Resources and Tools:

• Material Design 3 Guidelines
• Kotlin Multiplatform Documentation
• Jetpack Compose Material 3
• Material Theme Builder
• KMP Project Templates