material-components_material-components-android/docs/components/BottomAppBar.md

Bottom app bars

Note: The bottom app bar is being deprecated and should be replaced with the docked toolbar, which functions similarly, but is shorter and has more flexibility.

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

Note: Images use various dynamic color schemes.

Bottom app bars provide access to up to four actions, including the floating action button (FAB).

Design & API documentation

• Material 2 (M2) spec
• API reference

Anatomy

1. Container
2. Floating action button (FAB) (optional)
3. Action item(s) (optional)
4. Navigation icon (optional)
5. Overflow menu (optional)

Note: This doc reflects the Bottom App Bar after the changes in 1.7 to reflect the current M3 style. Use Widget.Material3.BottomAppBar.Legacy to revert back to the previous style.

M3 Expressive update

Before you can use Material3Expressive component styles, follow the Material3Expressive themes setup instructions.

The bottom app bar is being deprecated and should be replaced with the docked toolbar, which functions similarly, but is shorter and has more flexibility.

Types and naming:

• Added docked toolbar to replace bottom app bar

  • Size: Shorter height
  • Color: Standard or vibrant
  • Flexibility: More layout and element options

• Bottom app bar is still available, but not recommended

Key properties

Container attributes

Element	Attribute	Related method(s)	Default value
Color	app:backgroundTint	setBackgroundTint getBackgroundTint	?attr/colorSurfaceContainer
Elevation	app:elevation	setElevation	3dp
Height	android:minHeight	setMinimumHeight getMinimumHeight	80dp
Shadows	app:addElevationShadow	N/A	false

Navigation icon attributes

Element	Attribute	Related method(s)	Default value
Icon	app:navigationIcon	setNavigationIcon getNavigationIcon	null
Color	app:navigationIconTint	setNavigationIconTint	?attr/colorOnSurfaceVariant (as Drawable tint)

FAB attributes

Element	Attribute	Related method(s)	Default value
Alignment mode	app:fabAlignmentMode	setFabAlignmentMode getFabAlignmentMode	end
Animation mode	app:fabAnimationMode	setFabAnimationMode getFabAnimationMode	slide
Anchor mode	app:fabAnchorMode	setFabAnchorMode getFabAnchorMode	embed
Cradle margin	app:fabCradleMargin	setFabCradleMargin getFabCradleMargin	6dp
Cradle rounded corner radius	app:fabCradleRoundedCornerRadius	setFabCradleRoundedCornerRadius getFabCradleRoundedCornerRadius	4dp
Cradle vertical offset	app:fabCradleVerticalOffset	setCradleVerticalOffset getCradleVerticalOffset	12dp
End margin	app:fabAlignmentModeEndMargin	setFabAlignmentModeEndMargin getFabAlignmentModeEndMargin	16dp
Embedded elevation	app:removeEmbeddedFabElevation	N/A	true

See the FAB documentation for more attributes.

Action item(s) attributes

Element	Attribute	Related method(s)	Default value
Menu	app:menu	replaceMenu getMenu	null
Icon color	N/A	N/A	?attr/colorControlNormal (as Drawable tint)
Alignment mode	app:menuAlignmentMode	setMenuAlignmentMode getMenuAlignmentMode	start

Overflow menu attributes

Element	Attribute	Related method(s)	Default value
Icon	android:src and app:srcCompat in actionOverflowButtonStyle (in app theme)	setOverflowIcon getOverflowIcon	@drawable/abc_ic_menu_overflow_material (before API 23) or @drawable/ic_menu_moreoverflow_material (after API 23)
Theme	app:popupTheme	setPopupTheme getPopupTheme	@style/ThemeOverlay.Material3.*
Item typography	textAppearanceSmallPopupMenu and textAppearanceLargePopupMenu in app:popupTheme or app theme	N/A	?attr/textAppearanceTitleMedium

Styles

Element	Style	Theme attribute
Default style	Widget.Material3.BottomAppBar	bottomAppBarStyle

See the full list of styles and attrs.

Code implementation

Before you can use Material bottom app bars, you need to add a dependency to the Material Components for Android library. For more information, go to the Getting started page.

Bottom app bar examples

The following example shows a bottom app bar with a navigation icon, 3 action icons, and an embedded FAB.

In the layout:

<androidx.coordinatorlayout.widget.CoordinatorLayout
    ...
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <!-- Note: A RecyclerView can also be used -->
    <androidx.core.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:paddingBottom="100dp"
        android:clipToPadding="false">

        <!-- Scrollable content -->

    </androidx.core.widget.NestedScrollView>

    <com.google.android.material.bottomappbar.BottomAppBar
        android:id="@+id/bottomAppBar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        app:navigationIcon="@drawable/ic_drawer_menu_24px"
        app:menu="@menu/bottom_app_bar"
        />

    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:srcCompat="@drawable/ic_add_24dp"
        app:layout_anchor="@id/bottomAppBar"
        />

</androidx.coordinatorlayout.widget.CoordinatorLayout>

In menu/bottom_app_bar.xml:

<menu
      ...>
    <item
      android:id="@+id/accelerator"
      android:icon="@drawable/ic_accelerator_24px"
      android:title="@string/accelerator"
      android:contentDescription="@string/content_description_accelerator"
      app:showAsAction="ifRoom"/>

    <item
      android:id="@+id/rotation"
      android:icon="@drawable/ic_3d_rotation_24px"
      android:title="@string/rotation"
      android:contentDescription="@string/content_description_rotation"
      app:showAsAction="ifRoom"/>

    <item
      android:id="@+id/dashboard"
      android:icon="@drawable/ic_dashboard_24px"
      android:title="@string/dashboard"
      android:contentDescription="@string/content_description_dashboard"
      app:showAsAction="ifRoom"/>

</menu>

In menu/navigation icon drawables:

<vector
    ...
    android:tint="?attr/colorControlNormal">
    ...
</vector>

In code:

bottomAppBar.setNavigationOnClickListener {
    // Handle navigation icon press
}

bottomAppBar.setOnMenuItemClickListener { menuItem ->
    when (menuItem.itemId) {
        R.id.accelerator -> {
            // Handle accelerator icon press
            true
        }
        R.id.rotation -> {
            // Handle rotation icon press
            true
        }
        R.id.dashboard -> {
            // Handle dashboard icon press
            true
        }
        else -> false
    }
}

Making bottom app bars accessible

Android's bottom app bar component APIs provide support for the navigation icon, action items, overflow menu and more to tell the user what each action performs. While optional, their use is strongly encouraged.

Content descriptions

When using navigation icons, action items and other elements of bottom app bars, you should set a content description for them so that screen readers like TalkBack are able to announce their purpose or action.

For an overall content description of the bottom app bar, set an android:contentDescription or use the setContentDescription method on the BottomAppBar.

For the navigation icon, use the app:navigationContentDescription attribute or setNavigationContentDescription method.

For action items and items within the overflow menu, set the content description in the menu:

<menu ...>
    ...
    <item
          ...
          android:contentDescription="@string/content_description_one" />
    <item
          ...
          android:contentDescription="@string/content_description_two" />
</menu>

Talkback

Bottom app bar can optionally hide on scroll with the app:hideOnScroll attribute. When this attribute is set to true, scrolling will hide the bottom app bar and prevent it from being seen by any screen readers which may be confusing for users. To prevent this, the hide behavior is automatically disabled when Talkback is enabled. Although discouraged for accessibility, you can optionally force the hide behavior by calling bottomAppBar.disableHideOnTouchExploration(false).

Depending on your layout, disabling the hide behavior may potentially cause content to be obscured behind the bar. Make sure to add the appropriate bottom padding of the height of the bottom app bar to the content. See below for an example:

val am = context.getSystemService(AccessibilityManager::class.java)
if (am != null && am.isTouchExplorationEnabled) {
    bar.setHideOnScroll(false)
    bar.post {
        content.setPadding(
            content.paddingLeft,
            content.paddingTop,
            content.paddingRight,
            content.paddingBottom + bar.measuredHeight
        )
    }
}

Applying scrolling behavior to bottom app bars

The following example shows the bottom app bar hiding when scrolling the scrollable content down, and appearing when scrolling up.

<androidx.coordinatorlayout.widget.CoordinatorLayout
    ...>

    ...

    <com.google.android.material.bottomappbar.BottomAppBar
        ...
        app:hideOnScroll="true"
        />

    ...

</androidx.coordinatorlayout.widget.CoordinatorLayout>

Customizing bottom app bars

Theming bottom app bars

Bottom app bars support the customization of color, typography, and shape.

Bottom app bar theming example

API and source code:

• CoordinatorLayout
  • Class definition
• BottomAppBar
  • Class definition
  • Class source
• FloatingActionButton
  • Class definition
  • Class source
• BottomAppBarCutCornersTopEdge:
  • Class source

The following example shows a bottom app bar with Material theming.

Implementing bottom app bar theming

Use theme attributes in res/values/styles.xml, which applies the theme to all bottom app bars and FABs and affects other components:

<style name="Theme.App" parent="Theme.Material3.*">
    ...
    <item name="colorSurfaceContainer">@color/shrine_pink_100</item>
    <item name="colorOnSurface">@color/shrine_pink_900</item>
    <item name="colorPrimaryContainer">@color/shrine_pink_50</item>
    <item name="colorOnPrimaryContainer">@color/shrine_pink_900</item>
    <item name="textAppearanceTitleMedium">@style/TextAppearance.App.Medium</item>
    <item name="shapeAppearanceCornerLarge">@style/ShapeAppearance.App.Corner.Large</item>
</style>

<style name="TextAppearance.App.Medium" parent="TextAppearance.Material3.TitleMedium">
    <item name="fontFamily">@font/rubik</item>
    <item name="android:fontFamily">@font/rubik</item>
</style>

<style name="ShapeAppearance.App.Corner.Large" parent="ShapeAppearance.Material3.Corner.Large">
    <item name="cornerFamily">cut</item>
    <item name="cornerSize">50%</item>
</style>

Use default style theme attributes, styles and theme overlays, which applies the theme to all bottom app bars and FABs but does not affect other components:

<style name="Theme.App" parent="Theme.Material3.*">
    ...
    <item name="bottomAppBarStyle">@style/Widget.App.BottomAppBar</item>
    <item name="floatingActionButtonStyle">@style/Widget.App.FloatingActionButton</item>
</style>

<style name="Widget.App.BottomAppBar" parent="Widget.Material3.BottomAppBar">
    <item name="materialThemeOverlay">@style/ThemeOverlay.App.BottomAppBar</item>
</style>

<style name="Widget.App.FloatingActionButton" parent="Widget.Material3.FloatingActionButton.Primary">
    <item name="materialThemeOverlay">@style/ThemeOverlay.App.FloatingActionButton</item>
</style>

<style name="ThemeOverlay.App.BottomAppBar" parent="ThemeOverlay.Material3.BottomAppBar">
    <item name="colorSurfaceContainer">@color/shrine_pink_100</item>
    <item name="colorOnSurface">@color/shrine_pink_900</item>
    <item name="textAppearanceTitleMedium">@style/TextAppearance.App.TitleMedium</item>
</style>

<style name="ThemeOverlay.App.FloatingActionButton" parent="ThemeOverlay.Material3.FloatingActionButton.Primary">
    <item name="colorPrimaryContainer">@color/shrine_pink_50</item>
    <item name="colorOnPrimaryContainer">@color/shrine_pink_900</item>
    <item name="shapeAppearanceCornerLarge">@style/ShapeAppearance.App.Corner.Large</item>
</style>

Use the styles in the layout, which affects only this bottom app bar and FAB:

<com.google.android.material.bottomappbar.BottomAppBar
    ...
    style="@style/Widget.App.BottomAppBar"
    />

<com.google.android.material.floatingactionbutton.FloatingActionButton
    ...
    style="@style/Widget.App.FloatingActionButton"
    />