In Jetpack Compose, how can I display a large list of data while laying out only the visible items, instead of composing and laying out every item on the initial layout pass? This would be similar to RecyclerView
and ListView
in the View
toolkit.
One could use a for
loop to place all of the components inside of a Column
in a VerticalScroller
, but this would result in dropped frames and poor performance on larger numbers of items.
Note: this is intended as a canonical self-answered question to pre-empt/handle similar questions
Directly in jetpack compose does not support recycler view like the android app.
Jetpack Compose is designed to work with the established View-based UI approach. If you're building a new app, the best option might be to implement your entire UI with Compose.
Jetpack Compose is Android's modern toolkit for building native UI. It simplifies and accelerates UI development on Android. Quickly bring your app to life with less code, powerful tools, and intuitive Kotlin APIs.
A LazyRow is a horizontal scrolling list that only composes and lays out the currently visible items. It's similar to a horizontal Recyclerview in the classic Android View system.
The equivalent component to RecyclerView
or ListView
in Jetpack Compose is LazyColumn
for a vertical list and LazyRow
for a horizontal list. These compose and lay out only the currently visible items.
You can use it by formatting your data as a list and passing it with a @Composable
callback that emits the UI for a given item in the list. For example:
val myData = listOf("Hello,", "world!")
LazyColumn {
items(myData) { item ->
Text(text = item)
}
}
val myData = listOf("Hello,", "world!")
LazyRow {
items(myData) { item ->
Text(text = item)
}
}
You can also specify individual items one at a time:
LazyColumn {
item {
Text("Hello,")
}
item {
Text("world!")
}
}
LazyRow {
item {
Text("Hello,")
}
item {
Text("world!")
}
}
There are also indexed variants, which provide the index in the collection in addition to the item itself:
val myData = listOf("Hello,", "world!")
LazyColumn {
itemsIndexed(myData) { index, item ->
Text(text = "Item #$index is $item")
}
}
val myData = listOf("Hello,", "world!")
LazyRow {
itemsIndexed(myData) { index, item ->
Text(text = "Item #$index is $item")
}
}
These APIs were, in previous releases, known as AdapterList
, LazyColumnItems
/LazyRowItems
, and LazyColumnFor
/LazyRowFor
.
Update in dev.16
Check it's implementation from ListCardViewTemplate
You can get the same essence of RecyclerView
or ListView
in JetpackCompose using AdapterList
that's renamed in dev.14 preview version.
[LazyColumnItems]
for vertically scrolling list[LazyRowItems]
for horizontally scrolling listCheck what's documentation says:
It was also moved into a
lazy
sub-package and split into two files. Plus I renamed params:
- data -> items. this seems to be more meaningful then just raw
data
- itemCallback -> itemContent. this is more meaningful and we generally don't use word callback in the lambda names, especially for composable lambdas
Check how to use it:
@Composable
fun <T> LazyColumnItems(
items: List<T>,
modifier: Modifier = Modifier,
itemContent: @Composable (T) -> Unit
) {
LazyItems(items, modifier, itemContent, isVertical = true)
}
In .KT
LazyColumnItems(items = (0..50).toList()) { item ->
cardViewImplementer(item)
}
From my perspective
LazyColumnItem
orLazyRowItem
is not working properly if your item layout is complex because it's stuck the list as a comparison toVerticalScroller
working fine in this scenario.
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