remember
- Kotlin course
- Expert
- Lesson 33/47
- 5 min
Learn state retention with remember.
What is remember?
remember is a function that keeps a value across recompositions inside a composable. Compose does not reset variables on every redraw; remember stores them.
Example: val count = remember { mutableStateOf(0) }. This line creates the counter on the first draw and returns the same instance on later draws. Without remember, it would reset on every recomposition. This is the core way to keep UI state. The rememberInfo model in this lesson shows the concept.
A remember example
A counter composable holds state with remember. When the button is pressed, the counter increases and Compose redraws the related composable.
Example: val count = remember { mutableStateOf(0) }, then Button(onClick = { count.value++ }) { Text("${'$'}{count.value}") }. Each press increases count.value; Compose observes it and redraws the Text. remember keeps the counter without reset. This is the basis of reactive UI.
Practice Write rememberInfo
Define fun rememberInfo(): String. It should return "remember". In main, write println(rememberInfo()).
Starter code
// add the rememberInfo function
fun main() {
// print the remember info
}Sample solution
fun rememberInfo(): String = "remember"
fun main() {
println(rememberInfo())
}Expected output
remember
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Match the remember parts
| Term | Meaning |
|---|---|
remember |
State retention |
recomposition |
Redraw |
mutableStateOf |
Reactive state |
Composable |
UI function |
2 When does remember reset?
remember lasts the composable lifetime.- On every recomposition
- Until the app closes
- Until the component leaves the tree Correct answer
- Never
Explanation: remember keeps the value until the composable leaves the tree.
3 Complete the remember call
val count = remember { ____ }val count = remember { mutableStateOf(0) }Explanation: remember { mutableStateOf(0) } stores the reactive counter.