Jetpack Compose: Dive in to Strengths and Weaknesses

Jetpack Compose, developed by Google, represents a modern and declarative approach to building Android UI. Launched as part of Android Jetpack, Compose replaces the traditional XML-based UI system with Kotlin-based code, making UI creation more seamless and intuitive.

What is Jetpack Compose? #

Jetpack Compose is Android's modern toolkit for building native UI. It simplifies and accelerates UI development on Android by using a declarative programming model. Instead of imperatively manipulating UI components, you describe what your UI should look like based on the current state, and Compose takes care of the rest.

Strengths of Jetpack Compose #

1. Declarative UI Paradigm #

Compose adopts a declarative approach where you define your UI as a function of state. This means less boilerplate code and a more straightforward way to build and update UIs dynamically.

Example - Counter UI:

Imperative (XML + Activity):

// XML layout with TextView and Button
// Activity code:
class CounterActivity : AppCompatActivity() {
    private var count = 0
    private lateinit var textView: TextView

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_counter)

        textView = findViewById(R.id.countText)
        val button = findViewById<Button>(R.id.incrementButton)

        button.setOnClickListener {
            count++
            textView.text = "Count: $count" // Manual UI update
        }
    }
}

Declarative (Compose):

@Composable
fun CounterScreen() {
    var count by remember { mutableStateOf(0) }

    Column {
        Text("Count: $count")
        Button(onClick = { count++ }) {
            Text("Increment")
        }
    }
    // UI automatically updates when count changes
}

Notice how Compose automatically re-renders when state changes—no manual UI updates needed.

2. Kotlin-First #

Built entirely in Kotlin, Compose leverages Kotlin's concise syntax and powerful features like coroutines, extension functions, and lambdas, making it more expressive and safer than XML.

3. Less Boilerplate #

Traditional Android UI development involves lots of XML layouts (like ConstraintLayout) and findViewById calls. Compose eliminates much of this boilerplate, allowing developers to build UIs directly in Kotlin.

Example - Simple List:

XML + RecyclerView:

<!-- layout_item.xml -->
<LinearLayout...>
    <TextView android:id="@+id/nameText" />
    <TextView android:id="@+id/emailText" />
</LinearLayout>

// Adapter class
class UserAdapter(private val users: List<User>) :
    RecyclerView.Adapter<UserViewHolder>() {

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): UserViewHolder {
        val view = LayoutInflater.from(parent.context)
            .inflate(R.layout.layout_item, parent, false)
        return UserViewHolder(view)
    }

    override fun onBindViewHolder(holder: UserViewHolder, position: Int) {
        holder.bind(users[position])
    }

    override fun getItemCount() = users.size
}

class UserViewHolder(view: View) : RecyclerView.ViewHolder(view) {
    private val nameText: TextView = view.findViewById(R.id.nameText)
    private val emailText: TextView = view.findViewById(R.id.emailText)

    fun bind(user: User) {
        nameText.text = user.name
        emailText.text = user.email
    }
}

Compose LazyColumn:

@Composable
fun UserList(users: List<User>) {
    LazyColumn {
        items(users) { user ->
            Column {
                Text(user.name)
                Text(user.email)
            }
        }
    }
}

From ~40 lines with XML/Adapter to ~10 lines in Compose!

4. Live Preview and Tooling #

Android Studio provides excellent tooling support for Compose, including live preview, interactive mode, and better debugging capabilities.

5. Composable Functions #

UI components in Compose are just functions (composables), making them easy to test, reuse, and compose together to build complex UIs.

6. Animation Support #

Compose has built-in APIs for animations that are simple yet powerful, enabling smooth and performant animations with minimal code.

Weaknesses of Jetpack Compose #

1. Learning Curve #

For developers used to the imperative XML-based approach, switching to a declarative paradigm requires a mindset shift and time to learn new concepts.

2. Library Maturity #

While stable, Compose is still relatively new compared to the traditional View system. Some third-party libraries and components may not have Compose equivalents yet.

3. Build Times #

In some cases, projects using Compose may experience longer build times, especially as the project grows in size.

4. Backward Compatibility #

Compose requires Android API level 21 (Lollipop) or higher, which may limit its use in apps targeting very old devices.

5. Ecosystem Transition #

Many existing Android libraries and tools are built around XML views. Integrating these with Compose (via interop) can sometimes be cumbersome.

XML vs Compose: Side-by-Side Comparisons #

State Management #

State Management Example:

XML Approach:

// ViewModel
class UserViewModel : ViewModel() {
    private val _username = MutableLiveData<String>()
    val username: LiveData<String> = _username

    fun updateUsername(name: String) {
        _username.value = name
    }
}

// Fragment/Activity
class UserFragment : Fragment() {
    private val viewModel: UserViewModel by viewModels()

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        val textView = view.findViewById<TextView>(R.id.usernameText)

        viewModel.username.observe(viewLifecycleOwner) { name ->
            textView.text = name
        }
    }
}

Compose Approach:

@Composable
fun UserScreen(viewModel: UserViewModel = viewModel()) {
    val username by viewModel.username.collectAsStateWithLifecycle()

    Text(text = username)
}

Navigation Comparison #

Performance Considerations #

Build Time Comparison #

Runtime Performance #

Compose uses smart recomposition - only recomposing parts of the UI that actually changed. This is often more efficient than traditional view invalidation.

Best Practices for Compose Performance:

• Use remember to cache expensive calculations
• Avoid creating new lambdas in composables unnecessarily
• Use derivedStateOf for computed state
• Leverage LaunchedEffect for side effects
• Use key() in LazyColumn for stable item identity

Migration Strategy: When and How? #

Should You Migrate? #

Migrate to Compose if:

• ✅ Starting a new project or feature
• ✅ Team is comfortable with Kotlin and modern Android
• ✅ App targets API 21+ (which most apps do)
• ✅ You want to reduce boilerplate and improve developer velocity
• ✅ Building dynamic, interactive UIs

Stick with XML Views if:

• ⚠️ Large existing codebase with complex custom views
• ⚠️ Team lacks Kotlin experience
• ⚠️ App heavily depends on XML-only libraries
• ⚠️ Tight deadlines with no time for learning curve
• ⚠️ Supporting very old Android versions (< API 21)

Gradual Migration Approach #

You don't need to migrate everything at once. Compose and XML Views can coexist:

1. Compose in XML (ComposeView):

<!-- layout.xml -->
<LinearLayout...>
    <TextView ... />

    <androidx.compose.ui.platform.ComposeView
        android:id="@+id/composeView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
</LinearLayout>

// Activity/Fragment
composeView.setContent {
    MaterialTheme {
        MyComposeContent()
    }
}

2. XML in Compose (AndroidView):

@Composable
fun LegacyWebView() {
    AndroidView(
        factory = { context ->
            WebView(context).apply {
                // Configure WebView
            }
        }
    )
}

Migration Steps #

1. Start with New Screens - Build new features in Compose
2. Migrate Simple Screens - Convert simple XML screens to Compose
3. Shared Components - Create Compose versions of common UI components
4. Complex Screens Last - Migrate complex screens after team gains experience
5. Remove XML Gradually - Clean up XML as Compose coverage increases

When NOT to Use Compose #

1. Complex Custom Views with Canvas #

If you have heavily optimized custom views using Canvas drawing, the migration effort might not be worth it immediately.

2. WebView-Heavy Apps #

Apps that primarily display web content don't benefit much from Compose.

3. Tight Performance Constraints #

For apps with extremely tight performance requirements on low-end devices, stick with the mature XML system until you can thoroughly test Compose performance.

4. Third-Party Library Dependencies #

If your app heavily relies on libraries that provide XML-only UI components with no Compose alternatives.

Best Practices for Compose Development #

1. State Hoisting #

Lift state up to make composables reusable and testable:

// ❌ Bad: State inside composable
@Composable
fun SearchBar() {
    var query by remember { mutableStateOf("") }
    TextField(value = query, onValueChange = { query = it })
}

// ✅ Good: State hoisted
@Composable
fun SearchBar(
    query: String,
    onQueryChange: (String) -> Unit
) {
    TextField(value = query, onValueChange = onQueryChange)
}

2. Use @Stable and @Immutable #

Help Compose optimize recomposition:

@Immutable
data class User(val name: String, val email: String)

@Stable
interface UserRepository {
    fun getUsers(): List<User>
}

3. Avoid Side Effects in Composables #

Use LaunchedEffect, DisposableEffect, or SideEffect for side effects:

@Composable
fun UserProfile(userId: String, viewModel: UserViewModel) {
    LaunchedEffect(userId) {
        viewModel.loadUser(userId)
    }

    val user by viewModel.user.collectAsState()
    // UI code
}

4. Preview Your Composables #

Always add preview functions for faster development:

@Preview(showBackground = true)
@Composable
fun UserCardPreview() {
    MaterialTheme {
        UserCard(User("John Doe", "[email protected]"))
    }
}

Conclusion #

Jetpack Compose represents a significant step forward in Android UI development, offering a modern, efficient, and enjoyable way to build user interfaces. While it comes with a learning curve and some ecosystem challenges, its benefits—such as reduced boilerplate, better tooling, and Kotlin-first design—make it a compelling choice for new Android projects. As the ecosystem matures, Compose is likely to become the standard for Android UI development.

The future of Compose design looks even more exciting with Android 16's Material 3 Expressive, which brings emotion-driven UX and enhanced theming capabilities specifically designed for Compose applications.

Whether you're starting a new project or considering migrating an existing one, Jetpack Compose is definitely worth exploring!