Kotlin·Kotlin from syntax to a coroutine app

Android with Compose

Build a small screen with composable functions and state.

Beginner 14 min read Lesson 7 of 300 Challenge included

What you will be able to do

Use @Composable functions for UI.
Use remember { mutableStateOf(...) } for state.
Hoist state to the caller for reuse.
Preview components in Android Studio.

In plain English

Jetpack Compose describes UI with functions. State drives recomposition: remember and mutableStateOf hold local state, and state hoisting keeps components reusable.

Counter.ktKotlin

@Composable
fun Counter() {
    var count by remember { mutableStateOf(0) }
    Column(modifier = Modifier.padding(16.dp)) {
        Text("Clicked $count times")
        Button(onClick = { count += 1 }) {
            Text("Increment")
        }
    }
}

Your turn

Hold local state

Easy

Create a remembered mutable state for a counter.

KOTLIN · starter

var count =

Check your understanding before moving on.

Knowledge checkQuestion 1

What triggers recomposition in Compose?

Select an answer to continue

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Next: Testing

Lesson 7 of 300 · 0% of course