Jetpack Compose in Android: The Modern Way to Build Stunning UIs Faster

If you’re an Android developer looking to modernize your app’s UI, Jetpack Compose is the toolkit you’ve been waiting for. Say goodbye to XML layouts and complex view hierarchies—Compose makes UI development faster, easier, and more intuitive.

In this complete guide, we’ll explore what Jetpack Compose is, why it’s a game-changer for Android development, and how you can start using it today. Whether you’re building new apps or upgrading old ones, Jetpack Compose can drastically improve your workflow and user experience.

What is Jetpack Compose?

Jetpack Compose is Android’s modern UI toolkit built entirely with Kotlin. It allows developers to create beautiful, responsive UIs using declarative code instead of the traditional imperative XML layout system.

Key Highlights of Jetpack Compose:

Fully written in Kotlin
No need for XML
Reactive and declarative approach
Seamless integration with existing Jetpack libraries
Compatible with Material Design

Jetpack Compose helps you focus on what your UI should look like, not how to construct it step-by-step.

Why Use Jetpack Compose?

Here’s why Jetpack Compose has become the preferred way to build Android UIs:

1. Less Code, More Power

You can create complex UIs with significantly less code compared to XML-based layouts.

2. Live Previews

With Compose, you can preview your UI in real-time without deploying the app.

3. Reactive Programming

Compose updates the UI automatically when data changes—no more notifyDataSetChanged() headaches.

4. Easier Theming

Theming and styling are simpler and more consistent using Compose’s built-in support for Material Design.

Setting Up Jetpack Compose in Your Project

To get started with Jetpack Compose, make sure you’re using the latest Android Studio (preferably Giraffe or newer).

Step-by-Step Setup:

Update your build.gradle files:

In build.gradle (Project):

buildscript {
    ext {
        compose_ui_version = '1.5.0'
    }
}

In build.gradle (Module):

dependencies {
    implementation "androidx.compose.ui:ui:$compose_ui_version"
    implementation "androidx.compose.material:material:$compose_ui_version"
    implementation "androidx.compose.ui:ui-tooling-preview:$compose_ui_version"
    implementation "androidx.lifecycle:lifecycle-runtime-ktx:2.6.1"
    implementation "androidx.activity:activity-compose:1.7.2"
}

Enable Jetpack Compose in your module:

android {
    buildFeatures {
        compose true
    }
    composeOptions {
        kotlinCompilerExtensionVersion = compose_ui_version
    }
}

Jetpack Compose Basics: Building Your First UI

Let’s look at a simple Compose UI example.

@Composable
fun Greeting(name: String) {
    Text(text = "Hello, $name!", style = MaterialTheme.typography.h5)
}

@Preview
@Composable
fun PreviewGreeting() {
    Greeting(name = "Android Dev")
}

Key Components:

@Composable: Marks the function as a UI component.
Text: Basic UI element for displaying text.
@Preview: Enables real-time preview inside Android Studio.

Core Jetpack Compose Components

1. Text

Displays text on the screen.

Text("Welcome to Jetpack Compose!")

2. Button

Clickable button with an action.

Button(onClick = { /* Do something */ }) {
    Text("Click Me")
}

3. Column & Row

Layouts that arrange child elements vertically or horizontally.

Column {
    Text("Item 1")
    Text("Item 2")
}

4. Image

Displays images using a drawable or URL.

Image(painter = painterResource(R.drawable.my_image), contentDescription = "My Image")

State Management in Jetpack Compose

Compose is built to handle reactive state. That means UI updates automatically when the underlying state changes.

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

    Column {
        Text("Clicked $count times")
        Button(onClick = { count++ }) {
            Text("Click me")
        }
    }
}

remember stores state across recompositions.

mutableStateOf() holds the data.

Jetpack Compose with ViewModel

Jetpack Compose works seamlessly with ViewModel for clean separation of concerns.

class MainViewModel : ViewModel() {
    private val _text = mutableStateOf("Initial Value")
    val text: State<String> = _text

    fun updateText(newText: String) {
        _text.value = newText
    }
}

In your UI:

@Composable
fun ViewModelExample(viewModel: MainViewModel = viewModel()) {
    val text by viewModel.text

    Column {
        Text(text)
        Button(onClick = { viewModel.updateText("Updated!") }) {
            Text("Update Text")
        }
    }
}

Testing with Jetpack Compose

Testing UI in Compose is much easier and more maintainable.

Example UI Test:

@get:Rule
val composeTestRule = createComposeRule()

@Test
fun testButtonClick() {
    composeTestRule.setContent {
        Counter()
    }

    composeTestRule.onNodeWithText("Click me").performClick()
    composeTestRule.onNodeWithText("Clicked 1 times").assertExists()
}

Pros and Cons of Jetpack Compose

Pros:

Clean and readable code
Fast iteration with live previews
No XML confusion
Built for Kotlin

Cons:

Learning curve for beginners
Not 100% backward-compatible with older Android APIs
Some components still evolving

Best Practices for Using Jetpack Compose

Use rememberSaveable for UI state that survives configuration changes
Keep composables small and reusable
Use Modifier for UI customization
Stick to unidirectional data flow for easier debugging

Jetpack Compose vs XML: Which One Should You Use?

Feature	Jetpack Compose	XML Layouts
Learning Curve	Medium	Easy for Beginners
Code Reusability	High	Medium
Real-time Preview	Yes	Yes
UI Logic Separation	Easy	Tricky
Performance	Fast	Depends

If you’re starting a new project or modernizing an old one, Jetpack Compose is the way to go.