Expanded class Null safety

A widget that expands a child of a Row, Column, or Flex so that the child fills the available space.

Using an Expanded widget makes a child of a Row, Column, or Flex expand to fill the available space along the main axis (e.g., horizontally for a Row or vertically for a Column). If multiple children are expanded, the available space is divided among them according to the flex factor.

An Expanded widget must be a descendant of a Row, Column, or Flex, and the path from the Expanded widget to its enclosing Row, Column, or Flex must contain only StatelessWidgets or StatefulWidgets (not other kinds of widgets, like RenderObjectWidgets).

This example shows how to use an Expanded widget in a Column so that its middle child, a Container here, expands to fill the space.

This results in two thin blue boxes with a larger amber box in between.

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

This example shows how to use an Expanded widget in a Row with multiple children expanded, utilizing the flex factor to prioritize available space.

This results in a wide amber box, followed by a thin blue box, with a medium width amber box at the end.

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

See also:

Inheritance

Constructors

Expanded({Key? key, int flex: 1, required Widget child})
Creates a widget that expands a child of a Row, Column, or Flex so that the child fills the available space along the flex widget's main axis.
const

Properties

child Widget
The widget below this widget in the tree. [...]
final, inherited
debugTypicalAncestorWidgetClass Type
The RenderObjectWidget that is typically used to set up the ParentData that applyParentData will write to. [...]
read-only, inherited
fit FlexFit
How a flexible child is inscribed into the available space. [...]
final, inherited
flex int
The flex factor to use for this child. [...]
final, inherited
hashCode int
The hash code for this object. [...]
@nonVirtual, read-only, inherited
key Key?
Controls how one widget replaces another widget in the tree. [...]
final, inherited
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited

Methods

applyParentData(RenderObject renderObject) → void
Write the data from this widget into the given render object's parent data. [...]
inherited
createElement() ParentDataElement<FlexParentData>
Inflates this configuration to a concrete instance. [...]
inherited
debugCanApplyOutOfTurn() bool
Whether the ParentDataElement.applyWidgetOutOfTurn method is allowed with this widget. [...]
@protected, inherited
debugDescribeChildren() List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children. [...]
@protected, inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node. [...]
inherited
debugIsValidRenderObject(RenderObject renderObject) bool
Checks if this widget can apply its parent data to the provided renderObject. [...]
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed. [...]
inherited
toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) DiagnosticsNode
Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep. [...]
inherited
toString({DiagnosticLevel minLevel: DiagnosticLevel.info}) String
A string representation of this object. [...]
inherited
toStringDeep({String prefixLineOne: '', String? prefixOtherLines, DiagnosticLevel minLevel: DiagnosticLevel.debug}) String
Returns a string representation of this node and its descendants. [...]
inherited
toStringShallow({String joiner: ', ', DiagnosticLevel minLevel: DiagnosticLevel.debug}) String
Returns a one-line detailed description of the object. [...]
inherited
toStringShort() String
A short, textual description of this widget.
inherited

Operators

operator ==(Object other) bool
The equality operator. [...]
@nonVirtual, inherited