Listenable class Null safety

An object that maintains a list of listeners.

The listeners are typically used to notify clients that the object has been updated.

There are two variants of this interface:

Many classes in the Flutter API use or implement these interfaces. The following subclasses are especially relevant:

The terms "notify clients", "send notifications", "trigger notifications", and "fire notifications" are used interchangeably.

See also:

Implementers

Constructors

Listenable()
Abstract const constructor. This constructor enables subclasses to provide const constructors so that they can be used in const expressions.
const
Listenable.merge(List<Listenable?> listenables)
Return a Listenable that triggers when any of the given Listenables themselves trigger. [...]
factory

Properties

hashCode int
The hash code for this object. [...]
read-only, inherited
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited

Methods

addListener(VoidCallback listener) → void
Register a closure to be called when the object notifies its listeners.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed. [...]
inherited
removeListener(VoidCallback listener) → void
Remove a previously registered closure from the list of closures that the object notifies.
toString() String
Returns a string representation of this object.
inherited

Operators

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