BottomAppBar

Composable Component

A bottom app bar displays navigation and key actions at the bottom of small screens.

Common

@Composable
fun BottomAppBar(
    actions: @Composable RowScope.() -> Unit,
    modifier: Modifier = Modifier,
    floatingActionButton: @Composable (() -> Unit)? = null,
    containerColor: Color = BottomAppBarDefaults.containerColor,
    contentColor: Color = contentColorFor(containerColor),
    tonalElevation: Dp = BottomAppBarDefaults.ContainerElevation,
    contentPadding: PaddingValues = BottomAppBarDefaults.ContentPadding,
    windowInsets: WindowInsets = BottomAppBarDefaults.windowInsets,
) =
    BottomAppBar(
        actions = actions,
        modifier = modifier,
        floatingActionButton = floatingActionButton,
        containerColor = containerColor,
        contentColor = contentColor,
        tonalElevation = tonalElevation,
        contentPadding = contentPadding,
        windowInsets = windowInsets,
        scrollBehavior = null,
    )

Parameters


actions	the icon content of this BottomAppBar. The default layout here is a `Row`, so content inside will be placed horizontally.
modifier	the `Modifier` to be applied to this BottomAppBar
floatingActionButton	optional floating action button at the end of this BottomAppBar
containerColor	the color used for the background of this BottomAppBar. Use `Color.Transparent` to have no color.
contentColor	the preferred color for content inside this BottomAppBar. Defaults to either the matching content color for `containerColor`, or to the current `LocalContentColor` if `containerColor` is not a color from the theme.
tonalElevation	when `containerColor` is `ColorScheme.surface`, a translucent primary color overlay is applied on top of the container. A higher tonal elevation value will result in a darker color in light theme and lighter color in dark theme. See also: `Surface`.
contentPadding	the padding applied to the content of this BottomAppBar
windowInsets	a window insets that app bar will respect.

Common

@ExperimentalMaterial3Api
@Composable
fun BottomAppBar(
    actions: @Composable RowScope.() -> Unit,
    modifier: Modifier = Modifier,
    floatingActionButton: @Composable (() -> Unit)? = null,
    containerColor: Color = BottomAppBarDefaults.containerColor,
    contentColor: Color = contentColorFor(containerColor),
    tonalElevation: Dp = BottomAppBarDefaults.ContainerElevation,
    contentPadding: PaddingValues = BottomAppBarDefaults.ContentPadding,
    windowInsets: WindowInsets = BottomAppBarDefaults.windowInsets,
    scrollBehavior: BottomAppBarScrollBehavior? = null,
) =
    BottomAppBar(
        modifier = modifier,
        containerColor = containerColor,
        contentColor = contentColor,
        tonalElevation = tonalElevation,
        windowInsets = windowInsets,
        contentPadding = contentPadding,
        scrollBehavior = scrollBehavior,
    ) {
        Row(
            modifier = Modifier.weight(1f),
            horizontalArrangement = Arrangement.Start,
            verticalAlignment = Alignment.CenterVertically,
            content = actions,
        )
        if (floatingActionButton != null) {
            Box(
                Modifier.fillMaxHeight()
                    .padding(top = FABVerticalPadding, end = FABHorizontalPadding),
                contentAlignment = Alignment.TopStart,
            ) {
                floatingActionButton()
            }
        }
    }

Parameters


actions	the icon content of this BottomAppBar. The default layout here is a `Row`, so content inside will be placed horizontally.
modifier	the `Modifier` to be applied to this BottomAppBar
floatingActionButton	optional floating action button at the end of this BottomAppBar
containerColor	the color used for the background of this BottomAppBar. Use `Color.Transparent` to have no color.
contentColor	the preferred color for content inside this BottomAppBar. Defaults to either the matching content color for `containerColor`, or to the current `LocalContentColor` if `containerColor` is not a color from the theme.
tonalElevation	when `containerColor` is `ColorScheme.surface`, a translucent primary color overlay is applied on top of the container. A higher tonal elevation value will result in a darker color in light theme and lighter color in dark theme. See also: `Surface`.
contentPadding	the padding applied to the content of this BottomAppBar
windowInsets	a window insets that app bar will respect.
scrollBehavior	a `BottomAppBarScrollBehavior` which holds various offset values that will be applied by this bottom app bar to set up its height. A scroll behavior is designed to work in conjunction with a scrolled content to change the bottom app bar appearance as the content scrolls. Note that the bottom app bar will not react to scrolling in case a touch exploration service (e.g., TalkBack) is active. See `BottomAppBarScrollBehavior.nestedScrollConnection`.

Common

@Composable
fun BottomAppBar(
    modifier: Modifier = Modifier,
    containerColor: Color = BottomAppBarDefaults.containerColor,
    contentColor: Color = contentColorFor(containerColor),
    tonalElevation: Dp = BottomAppBarDefaults.ContainerElevation,
    contentPadding: PaddingValues = BottomAppBarDefaults.ContentPadding,
    windowInsets: WindowInsets = BottomAppBarDefaults.windowInsets,
    content: @Composable RowScope.() -> Unit,
) =
    BottomAppBar(
        modifier = modifier,
        containerColor = containerColor,
        contentColor = contentColor,
        tonalElevation = tonalElevation,
        contentPadding = contentPadding,
        windowInsets = windowInsets,
        scrollBehavior = null,
        content = content,
    )

Parameters


modifier	the `Modifier` to be applied to this BottomAppBar
containerColor	the color used for the background of this BottomAppBar. Use `Color.Transparent` to have no color.
contentColor	the preferred color for content inside this BottomAppBar. Defaults to either the matching content color for `containerColor`, or to the current `LocalContentColor` if `containerColor` is not a color from the theme.
tonalElevation	when `containerColor` is `ColorScheme.surface`, a translucent primary color overlay is applied on top of the container. A higher tonal elevation value will result in a darker color in light theme and lighter color in dark theme. See also: `Surface`.
contentPadding	the padding applied to the content of this BottomAppBar
windowInsets	a window insets that app bar will respect.
content	the content of this BottomAppBar. The default layout here is a `Row`, so content inside will be placed horizontally.

Common

@ExperimentalMaterial3Api
@Composable
fun BottomAppBar(
    modifier: Modifier = Modifier,
    containerColor: Color = BottomAppBarDefaults.containerColor,
    contentColor: Color = contentColorFor(containerColor),
    tonalElevation: Dp = BottomAppBarDefaults.ContainerElevation,
    contentPadding: PaddingValues = BottomAppBarDefaults.ContentPadding,
    windowInsets: WindowInsets = BottomAppBarDefaults.windowInsets,
    scrollBehavior: BottomAppBarScrollBehavior? = null,
    content: @Composable RowScope.() -> Unit,
)

Parameters


modifier	the `Modifier` to be applied to this BottomAppBar
containerColor	the color used for the background of this BottomAppBar. Use `Color.Transparent` to have no color.
contentColor	the preferred color for content inside this BottomAppBar. Defaults to either the matching content color for `containerColor`, or to the current `LocalContentColor` if `containerColor` is not a color from the theme.
tonalElevation	when `containerColor` is `ColorScheme.surface`, a translucent primary color overlay is applied on top of the container. A higher tonal elevation value will result in a darker color in light theme and lighter color in dark theme. See also: `Surface`.
contentPadding	the padding applied to the content of this BottomAppBar
windowInsets	a window insets that app bar will respect.
scrollBehavior	a `BottomAppBarScrollBehavior` which holds various offset values that will be applied by this bottom app bar to set up its height. A scroll behavior is designed to work in conjunction with a scrolled content to change the bottom app bar appearance as the content scrolls. Note that the bottom app bar will not react to scrolling in case a touch exploration service (e.g., TalkBack) is active. See `BottomAppBarScrollBehavior.nestedScrollConnection`.
content	the content of this BottomAppBar. The default layout here is a `Row`, so content inside will be placed horizontally.

Code Examples

SimpleBottomAppBar

@Preview
@Composable
fun SimpleBottomAppBar() {
    BottomAppBar(
        actions = {
            IconButton(onClick = { /* doSomething() */ }) {
                Icon(Icons.Filled.Menu, contentDescription = "Localized description")
            }
        }
    )
}

BottomAppBarWithFAB

@Preview
@Composable
fun BottomAppBarWithFAB() {
    BottomAppBar(
        actions = {
            IconButton(onClick = { /* doSomething() */ }) {
                Icon(Icons.Filled.Check, contentDescription = "Localized description")
            }
            IconButton(onClick = { /* doSomething() */ }) {
                Icon(Icons.Filled.Edit, contentDescription = "Localized description")
            }
        },
        floatingActionButton = {
            FloatingActionButton(
                onClick = { /* do something */ },
                containerColor = BottomAppBarDefaults.bottomAppBarFabColor,
                elevation = FloatingActionButtonDefaults.bottomAppBarFabElevation(),
            ) {
                Icon(Icons.Filled.Add, "Localized description")
            }
        },
    )
}

ExitAlwaysBottomAppBar

/**
 * A sample for a [BottomAppBar] that collapses when the content is scrolled up, and appears when
 * the content scrolled down.
 */
@OptIn(ExperimentalMaterial3Api::class)
@Preview
@Composable
fun ExitAlwaysBottomAppBar() {
    val scrollBehavior = BottomAppBarDefaults.exitAlwaysScrollBehavior()
    Scaffold(
        modifier = Modifier.nestedScroll(scrollBehavior.nestedScrollConnection),
        bottomBar = {
            BottomAppBar(
                actions = {
                    IconButton(onClick = { /* doSomething() */ }) {
                        Icon(Icons.Filled.Check, contentDescription = "Localized description")
                    }
                    IconButton(onClick = { /* doSomething() */ }) {
                        Icon(Icons.Filled.Edit, contentDescription = "Localized description")
                    }
                },
                scrollBehavior = scrollBehavior,
            )
        },
        floatingActionButton = {
            FloatingActionButton(
                modifier = Modifier.offset(y = 4.dp),
                onClick = { /* do something */ },
                containerColor = BottomAppBarDefaults.bottomAppBarFabColor,
                elevation = FloatingActionButtonDefaults.bottomAppBarFabElevation(),
            ) {
                Icon(Icons.Filled.Add, "Localized description")
            }
        },
        floatingActionButtonPosition = FabPosition.EndOverlay,
        content = { innerPadding ->
            LazyColumn(
                contentPadding = innerPadding,
                verticalArrangement = Arrangement.spacedBy(8.dp),
            ) {
                val list = (0..75).map { it.toString() }
                items(count = list.size) {
                    Text(
                        text = list[it],
                        style = MaterialTheme.typography.bodyLarge,
                        modifier = Modifier.fillMaxWidth().padding(horizontal = 16.dp),
                    )
                }
            }
        },
    )
}