DropdownButton<T> class

A Material Design button for selecting from a list of items.

A dropdown button lets the user select from a number of items. The button shows the currently selected item as well as an arrow that opens a menu for selecting another item.

Updating to DropdownMenu

There is a Material 3 version of this component, DropdownMenu that is preferred for applications that are configured for Material 3 (see ThemeData.useMaterial3). The DropdownMenu widget's visuals are a little bit different, see the Material 3 spec at m3.material.io/components/menus/guidelines for more details.

The DropdownMenu widget's API is also slightly different. To update from DropdownButton to DropdownMenu, you will need to make the following changes:

  1. Instead of using DropdownButton.items, which takes a list of DropdownMenuItems, use DropdownMenu.dropdownMenuEntries, which takes a list of DropdownMenuEntry's.

  2. Instead of using DropdownButton.onChanged, use DropdownMenu.onSelected, which is also a callback that is called when the user selects an entry.

  3. In DropdownMenu it is not required to track the current selection in your app's state. So, instead of tracking the current selection in the DropdownButton.value property, you can set the DropdownMenu.initialSelection property to the item that should be selected before there is any user action.

  4. You may also need to make changes to the styling of the DropdownMenu, see the properties in the DropdownMenu constructor for more details.

See the sample below for an example of migrating from DropdownButton to DropdownMenu.

Using DropdownButton

One ancestor must be a Material widget and typically this is provided by the app's Scaffold.

The type T is the type of the value that each dropdown item represents. All the entries in a given menu must represent values with consistent types. Typically, an enum is used. Each DropdownMenuItem in items must be specialized with that same type argument.

The onChanged callback should update a state variable that defines the dropdown's value. It should also call State.setState to rebuild the dropdown with the new value.

This sample shows a DropdownButton with a large arrow icon, purple text style, and bold purple underline, whose value is one of "One", "Two", "Three", or "Four".


To create a local project with this code sample, run:
flutter create --sample=material.DropdownButton.1 mysample

If the onChanged callback is null or the list of items is null then the dropdown button will be disabled, i.e. its arrow will be displayed in grey and it will not respond to input. A disabled button will display the disabledHint widget if it is non-null. However, if disabledHint is null and hint is non-null, the hint widget will instead be displayed.

This sample shows how you would rewrite the above DropdownButton to use the DropdownMenu.

To create a local project with this code sample, run:
flutter create --sample=material.DropdownButton.2 mysample

See also:



Creates a dropdown button.


alignment AlignmentGeometry
Defines how the hint or the selected item is positioned within the button.
autofocus bool
True if this widget will be selected as the initial focus when no other node in its scope is currently focused.
borderRadius BorderRadius?
Defines the corner radii of the menu's rounded rectangle shape.
disabledHint Widget?
A preferred placeholder widget that is displayed when the dropdown is disabled.
The background color of the dropdown.
elevation int
The z-coordinate at which to place the menu when open.
enableFeedback bool?
Whether detected gestures should provide acoustic and/or haptic feedback.
focusColor Color?
The color for the button's Material when it has the input focus.
focusNode FocusNode?
An optional focus node to use as the focus node for this widget.
hashCode int
The hash code for this object.
no setterinherited
hint Widget?
A placeholder widget that is displayed by the dropdown button.
icon Widget?
The widget to use for the drop-down button's icon.
iconDisabledColor Color?
The color of any Icon descendant of icon if this button is disabled, i.e. if onChanged is null.
iconEnabledColor Color?
The color of any Icon descendant of icon if this button is enabled, i.e. if onChanged is defined.
iconSize double
The size to use for the drop-down button's down arrow icon button.
isDense bool
Reduce the button's height.
isExpanded bool
Set the dropdown's inner contents to horizontally fill its parent.
itemHeight double?
If null, then the menu item heights will vary according to each menu item's intrinsic height.
items List<DropdownMenuItem<T>>?
The list of items the user can select.
key Key?
Controls how one widget replaces another widget in the tree.
The maximum height of the menu.
onChanged ValueChanged<T?>?
Called when the user selects an item.
onTap VoidCallback?
Called when the dropdown button is tapped.
padding EdgeInsetsGeometry?
Padding around the visible portion of the dropdown widget.
runtimeType Type
A representation of the runtime type of the object.
no setterinherited
selectedItemBuilder DropdownButtonBuilder?
A builder to customize the dropdown buttons corresponding to the DropdownMenuItems in items.
style TextStyle?
The text style to use for text in the dropdown button and the dropdown menu that appears when you tap the button.
underline Widget?
The widget to use for drawing the drop-down button's underline.
value → T?
The value of the currently selected DropdownMenuItem.


createElement() StatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
createState() State<DropdownButton<T>>
Creates the mutable state for this widget at a given location in the tree.
debugDescribeChildren() List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children.
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) DiagnosticsNode
Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.
toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) String
A string representation of this object.
toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug}) String
Returns a string representation of this node and its descendants.
toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) String
Returns a one-line detailed description of the object.
toStringShort() String
A short, textual description of this widget.


operator ==(Object other) bool
The equality operator.