Jetpack Compose vs XML: 10 Benefits of Modern Android UI Development with Kotlin

Introduction

Jetpack Compose offers several benefits over traditional XML-based UI development. It provides a modern way to build Android user interfaces using Kotlin and a declarative programming model.

Instead of defining a layout in an XML file and then finding and updating individual views from Kotlin code, Compose allows developers to describe the UI directly in Kotlin. When the application's state changes, Compose can automatically update the relevant parts of the UI.

In this article, we will look at the main benefits of Jetpack Compose and understand them through practical examples.

What Is Jetpack Compose?

Jetpack Compose is Android's modern toolkit for building native user interfaces with Kotlin. It uses composable functions to describe UI components.

For example, a simple text component can be created with:

@Composable
fun WelcomeMessage() {
    Text(text = "Welcome to my app")
}

A composable function describes what should appear on the screen. You can combine multiple composable functions to build a complete screen.

Jetpack Compose vs XML-Based UI

In the traditional Android View system, a UI is commonly defined using XML.

For example:

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Welcome to my app" />

The corresponding Compose implementation can be much more direct:

Text(text = "Welcome to my app")

With XML-based development, developers typically work between XML layout files and Kotlin or Java files. Compose allows UI definitions to live directly in Kotlin.

This does not mean XML-based development is no longer useful. Existing applications can continue using Views and XML, and Compose can also be introduced incrementally into an existing project.

Build a Simple UI with Jetpack Compose

Let's consider a simple user profile screen. The screen contains a user's name, email address, and a button.

@Composable
fun UserProfile() {
    Column(
        modifier = Modifier.padding(16.dp)
    ) {
        Text(
            text = "Vijay Kumari",
            style = MaterialTheme.typography.headlineSmall
        )

        Text(
            text = "[email protected]"
        )

        Button(
            onClick = {
                // Handle button click
            }
        ) {
            Text("Update Profile")
        }
    }
}

The UI is composed from smaller building blocks such as Column, Text, and Button.

This example demonstrates one of the important ideas behind Compose: instead of describing how individual views should be manipulated, the developer describes what the UI should contain.

1. Declarative UI Development

Jetpack Compose follows a declarative approach.

In an imperative UI system, developers commonly perform operations such as finding a view and changing its properties:

val textView = findViewById<TextView>(R.id.userName)
textView.text = "Vijay Kumari"

With Compose, the UI can be based directly on the current value:

@Composable
fun UserName(name: String) {
    Text(text = name)
}

If the value passed to name changes, Compose can recompose the affected UI.

Practical Example

Consider a counter:

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

    Column {
        Text(text = "Count: $count")

        Button(
            onClick = {
                count++
            }
        ) {
            Text("Increase")
        }
    }
}

The developer does not manually find the Text component and update its value. The UI reads the current state, and Compose handles the UI update when that state changes.

Benefit: This results in a more predictable UI structure and reduces the amount of manual view-update code.

2. Faster Development

With Compose, UI code is written directly in Kotlin. Developers do not need to switch between XML layout files and Kotlin files for every UI change.

For example:

@Composable
fun LoginButton() {
    Button(
        onClick = {
            // Login action
        }
    ) {
        Text("Login")
    }
}

The button, its text, and its click behavior can be defined together.

Compose also works with Android Studio's preview capabilities, allowing developers to inspect composables during development.

Benefit: Less boilerplate can make UI development and iteration faster, particularly for new screens.

3. Built-in State Management

State is an important part of modern application development. A UI often needs to react to changes such as text input, selections, loading states, or user actions.

Compose provides APIs such as remember and mutableStateOf for managing local UI state.

For example:

@Composable
fun Greeting() {
    var name by remember { mutableStateOf("") }

    Column(
        modifier = Modifier.padding(16.dp)
    ) {
        TextField(
            value = name,
            onValueChange = {
                name = it
            },
            label = {
                Text("Enter your name")
            }
        )

        Text(
            text = "Hello, $name"
        )
    }
}

When the user types into the text field, the name state changes. Compose then recomposes the parts of the UI that depend on that state.

Benefit: State-driven UI reduces the need for manual synchronization between UI controls and application state.

4. No Need for XML Layouts

A Compose screen can be defined completely using Kotlin.

For example:

@Composable
fun ProductCard() {
    Card(
        modifier = Modifier.padding(16.dp)
    ) {
        Column(
            modifier = Modifier.padding(16.dp)
        ) {
            Text("Laptop")
            Text("₹50,000")

            Button(
                onClick = {
                    // Add product to cart
                }
            ) {
                Text("Add to Cart")
            }
        }
    }
}

The layout hierarchy, styling, and interactions are all expressed through Kotlin code.

Benefit: Keeping UI code in Kotlin can reduce the number of files involved in implementing and maintaining a screen.

5. Reusability and Composition

One of the major strengths of Compose is the ability to create reusable composable functions.

Suppose an application displays product cards in several places. Instead of repeatedly defining the same UI, you can create a reusable component:

@Composable
fun ProductCard(
    productName: String,
    price: String
) {
    Card(
        modifier = Modifier.padding(8.dp)
    ) {
        Column(
            modifier = Modifier.padding(16.dp)
        ) {
            Text(text = productName)
            Text(text = price)
        }
    }
}

The same component can then be reused:

ProductCard(
    productName = "Laptop",
    price = "₹50,000"
)

ProductCard(
    productName = "Mobile Phone",
    price = "₹25,000"
)

Small composables can be combined to create larger screens.

Benefit: Composition encourages reusable components and helps keep larger UI implementations organized.

6. Better Integration with Kotlin Features

Jetpack Compose is built specifically for Kotlin, so developers can naturally use Kotlin features such as lambdas, higher-order functions, extension functions, and coroutines.

For example, a click action can be passed as a lambda:

@Composable
fun ActionButton(
    title: String,
    onClick: () -> Unit
) {
    Button(
        onClick = onClick
    ) {
        Text(title)
    }
}

The component does not need to know what should happen after the button is clicked.

The calling code can decide the behavior:

ActionButton(
    title = "Save",
    onClick = {
        // Save data
    }
)

Benefit: Kotlin's language features work naturally with composable functions, resulting in concise and flexible UI code.

7. Live Preview and Faster UI Iteration

Android Studio provides Preview support for composable functions.

For example:

@Preview(showBackground = true)
@Composable
fun UserProfilePreview() {
    UserProfile()
}

The preview allows developers to inspect the UI without navigating through the application every time they want to check a particular component.

This is especially useful while adjusting layouts, typography, spacing, and Material components.

Benefit: Preview support provides faster feedback during UI development and makes experimenting with individual components easier.

8. Integration with Material Design

Jetpack Compose provides Material components that can be customized according to an application's requirements.

For example:

@Composable
fun LoginScreen() {
    Column(
        modifier = Modifier.padding(16.dp)
    ) {
        TextField(
            value = "",
            onValueChange = {},
            label = {
                Text("Email")
            }
        )

        Button(
            onClick = {}
        ) {
            Text("Login")
        }
    }
}

Applications can also define a consistent theme for colors, typography, and shapes.

Benefit: Developers can build consistent interfaces using ready-to-use UI components rather than implementing common controls from scratch.

9. Access to Jetpack Libraries

Compose does not exist separately from the rest of the Android development ecosystem.

It can work with other Android and Jetpack components such as ViewModel, Navigation, Paging, and lifecycle-aware APIs.

For example, a ViewModel can expose UI state:

data class ProfileUiState(
    val name: String = "",
    val email: String = ""
)

A composable can receive that state:

@Composable
fun ProfileScreen(
    uiState: ProfileUiState
) {
    Column {
        Text(text = uiState.name)
        Text(text = uiState.email)
    }
}

This approach helps separate application state and business logic from the UI layer.

Benefit: Compose can be integrated into applications that already use the broader Android Jetpack ecosystem.

10. Better Performance Through Recomposition

Compose uses a recomposition model to update the UI when relevant state changes.

Consider this example:

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

    Column {
        Text(text = "Count: $count")

        Button(
            onClick = {
                count++
            }
        ) {
            Text("Increase")
        }
    }
}

When count changes, Compose determines which parts of the composition need to be recomposed.

This differs from manually updating multiple views after every state change.

However, performance still depends on how the application is designed. Poor state management, unnecessary recompositions, expensive work inside composables, and inefficient lists can still cause performance problems.

Benefit: Compose's declarative and state-driven model can make UI updates efficient when the UI is structured correctly.

Practical Comparison: Compose vs XML

The following table summarizes some common differences:

Area	XML + Views	Jetpack Compose
UI definition	XML layouts	Kotlin composables
UI updates	Usually handled through View APIs	Driven by state
Reusable UI	Custom Views/layouts	Composable functions
State handling	Separate state and View updates	Integrated with Compose state APIs
Kotlin integration	UI and XML are separate	UI is written directly in Kotlin
Preview	Layout preview	Compose Preview
Boilerplate	Generally higher for simple state-driven UI	Generally lower
Existing applications	Common and mature	Can be introduced incrementally

The choice depends on the application. Existing applications with large XML-based codebases may continue using Views, while new applications can consider Compose for new UI development.

When Should You Use Jetpack Compose?

Jetpack Compose can be a good choice when:

You are starting a new Android application.
You want to build UI directly with Kotlin.
Your application has state-driven interfaces.
You want reusable composable components.
You want to use Compose Preview during development.
You are comfortable with Kotlin.
You want to gradually modernize an existing Android application.

For an existing application, migration does not necessarily have to happen all at once. Compose and the traditional View system can coexist, allowing teams to migrate individual screens or components over time.

Common Mistakes to Avoid

Although Compose simplifies UI development, developers should still follow good architectural practices.

Avoid putting expensive operations directly inside composable functions:

@Composable
fun ProductScreen() {
    // Avoid performing expensive database or network operations here.
}

Instead, application logic and data operations should generally be handled through appropriate layers such as repositories and ViewModels.

It is also important to understand state ownership and recomposition. Not every value needs to be stored using remember, and application-level state should not automatically be treated as local UI state.

Conclusion

Jetpack Compose changes the way Android user interfaces are built by using a declarative, Kotlin-first approach.

Its major benefits include reduced boilerplate, state-driven UI, reusable composable functions, Kotlin integration, Material components, Preview support, Jetpack integration, and a recomposition-based UI model.

The biggest practical difference is that developers describe the UI based on the current state instead of manually updating individual views whenever something changes.

For new Android applications, Compose provides a modern approach to UI development. For existing XML-based applications, it can also be adopted gradually rather than requiring an immediate complete migration.