ActionListener class Null safety

A helper widget for making sure that listeners on an action are removed properly.

Listeners on the Action class must have their listener callbacks removed with Action.removeActionListener when the listener is disposed of. This widget helps with that, by providing a lifetime for the connection between the listener and the Action, and by handling the adding and removing of the listener at the right points in the widget lifecycle.

If you listen to an Action widget in a widget hierarchy, you should use this widget. If you are using an Action outside of a widget context, then you must call removeListener yourself.

link
This example shows how ActionListener handles adding and removing of the listener in the widget lifecycle.
To create a local project with this code sample, run:
flutter create --sample=widgets.ActionListener.1 mysample

Inheritance
Annotations

Constructors

ActionListener({Key? key, required ActionListenerCallback listener, required Action<Intent> action, required Widget child})
Create a const ActionListener.
const

Properties

action → Action<Intent>
The Action that the callback will be registered with.
final
child → Widget
This widget can only have one child. To lay out multiple children, let this widget's child be a widget such as Row, Column, or Stack, which have a children property, and then provide the children to that widget.
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
listener → ActionListenerCallback
The ActionListenerCallback callback to register with the action.
final
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() → State<ActionListener>
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