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.

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



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


action Action<Intent>
The Action that the callback will be registered with. [...]
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.
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
listener ActionListenerCallback
The ActionListenerCallback callback to register with the action. [...]
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited


createElement() StatefulElement
Creates a StatefulElement to manage this widget's location in the tree. [...]
createState() → _ActionListenerState
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. [...]
@protected, inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node. [...]
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent 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:}) 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. [...]
@nonVirtual, inherited