For over a decade, building UIs in Android meant one thing: XML layouts. It was a stable, well-understood, but often verbose and rigid system. Then came Jetpack Compose, Google's modern, fully declarative UI toolkit that represents the biggest shift in Android development since the introduction of Kotlin.

The debate is no longer *if* you should learn Compose, but *when* and *how* to adopt it. This article provides a clear, no-nonsense breakdown of the core differences, pros, and cons of each system to help you make informed decisions for your projects.

The Paradigm Shift: Imperative vs. Declarative

This is the fundamental difference that changes everything.

  • XML is Imperative: You create a layout of widgets (TextView, Button, etc.). Then, in your Kotlin/Java code, you find those widgets (findViewById) and manually command them to change (textView.text = "New Text", button.visibility = View.GONE). You are responsible for managing the state of each widget yourself.
  • Compose is Declarative: You describe what your UI *should* look like for a given state. You don't tell it how to change. When the state changes, the Compose framework intelligently redraws only the parts of the UI that are affected.
The Mental Model: With XML, you build a house and then manually renovate it room by room. With Compose, you give the system a blueprint, and whenever you update the blueprint, it automatically rebuilds the necessary parts of the house for you.

The Showdown: A Head-to-Head Comparison

Developer Experience & Speed

Compose wins, big time. Writing UI in pure Kotlin is a game-changer. You get type safety, powerful language features, and the ability to create reusable components with simple functions. The need to switch between XML and Kotlin contexts is gone. The interactive previews in Android Studio allow you to see your UI changes instantly without deploying to a device, which is a massive productivity boost.

A Simple Composable 
@Composable
fun Greeting(name: String) {
    Text(text = "Hello, $name!")
}

@Preview
@Composable
fun GreetingPreview() {
    MyTheme {
        Greeting("Android")
    }
}

Code Size and Boilerplate

Compose is the clear winner. It dramatically reduces the amount of code needed to build a UI. Gone are the days of findViewById, View Binding, Adapters for RecyclerViews, and managing widget states manually. This leads to cleaner, more readable, and more maintainable codebases.

Performance

It's a tie, with nuances. XML inflation can be slow, especially for complex layouts. Compose skips this step, but the initial composition of a complex screen can also be expensive. The real magic of Compose is "smart recomposition." It's incredibly efficient at redrawing only the tiny parts of the UI that have changed, which can lead to better runtime performance than a poorly managed XML view. However, it's also possible to write unperformant Compose code if you don't understand how state and recomposition work.

Learning Curve

XML has a lower initial barrier, but Compose has a higher ceiling. Most Android developers are already familiar with XML. Compose requires learning a new, declarative way of thinking about UI. You have to understand state management (`remember`, `StateFlow`), side effects (`LaunchedEffect`), and the composition/recomposition lifecycle. The initial learning curve is steeper, but once it clicks, it allows you to build more complex UIs faster.

Interoperability

Excellent on both sides. This is the killer feature that makes adoption feasible. You can gradually introduce Compose into an existing XML-based app screen by screen. You can use Compose inside an XML layout with the ComposeView, and you can use traditional XML Views inside a Composable with the AndroidView API. This means you don't have to rewrite your entire app.

The Verdict: Is XML Dead?

No, XML is not dead. It will be supported for many years to come, and there are millions of lines of stable, production XML code out there. However, there is no question that Jetpack Compose is the future of Android UI development. Google is investing all of its resources into Compose, and all new major features and libraries are being built with a Compose-first mindset.

  • For new projects in 2025: You should start with Jetpack Compose.
  • For existing projects: You should create a plan for gradual adoption. Start with new features or simple screens and build your team's confidence.

Learning Compose is no longer optional for an Android developer who wants to stay relevant. It's a powerful, productive, and fun way to build beautiful UIs, and it's here to stay.