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).

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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

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

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">@protectedinherited
debugDescribeChildren() → List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children.
protected">@protectedinherited
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">@nonVirtualinherited