ScaffoldMessenger class Null safety

Manages SnackBars and MaterialBanners for descendant Scaffolds.

This class provides APIs for showing snack bars and material banners at the bottom and top of the screen, respectively.

To display one of these notifications, obtain the ScaffoldMessengerState for the current BuildContext via ScaffoldMessenger.of and use the ScaffoldMessengerState.showSnackBar or the ScaffoldMessengerState.showMaterialBanner functions.

When the ScaffoldMessenger has nested Scaffold descendants, the ScaffoldMessenger will only present the notification to the root Scaffold of the subtree of Scaffolds. In order to show notifications for the inner, nested Scaffolds, set a new scope by instantiating a new ScaffoldMessenger in between the levels of nesting.

Here is an example of showing a SnackBar when the user presses a button.

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

Constructors

ScaffoldMessenger({Key? key, required Widget child}): Creates a widget that manages SnackBars for Scaffold descendants.
const

Properties

child → Widget: The widget below this widget in the tree.
final
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

createElement() → StatefulElement: Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() → ScaffoldMessengerState: Creates the mutable state for this widget at a given location in the tree.
override
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
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

Static Methods

maybeOf(BuildContext context) → ScaffoldMessengerState?: The state from the closest instance of this class that encloses the given context, if any.
of(BuildContext context) → ScaffoldMessengerState: The state from the closest instance of this class that encloses the given context.

Flutter
material
ScaffoldMessenger class