BlocListener<B extends Bloc<dynamic, S>, S> class

Takes a BlocWidgetListener and an optional bloc and invokes the listener in response to state changes in the bloc. It should be used for functionality that needs to occur only in response to a state change such as navigation, showing a SnackBar, showing a Dialog, etc... The listener is guaranteed to only be called once for each state change unlike the builder in BlocBuilder.

If the bloc parameter is omitted, BlocListener will automatically perform a lookup using BlocProvider and the current BuildContext.

BlocListener<BlocA, BlocAState>(
  listener: (context, state) {
    // do stuff here based on BlocA's state
  },
  child: Container(),
)

Only specify the bloc if you wish to provide a bloc that is otherwise not accessible via BlocProvider and the current BuildContext.

BlocListener<BlocA, BlocAState>(
  bloc: blocA,
  listener: (context, state) {
    // do stuff here based on BlocA's state
  },
  child: Container(),
)

An optional listenWhen can be implemented for more granular control over when listener is called. listenWhen will be invoked on each bloc state change. listenWhen takes the previous state and current state and must return a bool which determines whether or not the listener function will be invoked. The previous state will be initialized to the state of the bloc when the BlocListener is initialized. listenWhen is optional and if omitted, it will default to true.

BlocListener<BlocA, BlocAState>(
  listenWhen: (previous, current) {
    // return true/false to determine whether or not
    // to invoke listener with state
  },
  listener: (context, state) {
    // do stuff here based on BlocA's state
  }
  child: Container(),
)
Inheritance

Constructors

BlocListener({Key key, @required CubitWidgetListener<S> listener, B bloc, CubitListenerCondition<S> listenWhen, Widget child})
Takes a BlocWidgetListener and an optional bloc and invokes the listener in response to state changes in the bloc. It should be used for functionality that needs to occur only in response to a state change such as navigation, showing a SnackBar, showing a Dialog, etc... The listener is guaranteed to only be called once for each state change unlike the builder in BlocBuilder. [...]
const

Properties

child Widget
The widget which will be rendered as a descendant of the CubitListener.
final, inherited
cubit → B
The cubit whose state will be listened to. Whenever the cubit's state changes, listener will be invoked.
final, inherited
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 CubitWidgetListener<S>
The CubitWidgetListener which will be called on every state change. This listener should be used for any code which needs to execute in response to a state change.
final, inherited
listenWhen CubitListenerCondition<S>
An optional listenWhen can be implemented for more granular control over when listener is called. listenWhen will be invoked on each cubit state change. listenWhen takes the previous state and current state and must return a bool which determines whether or not the listener function will be invoked. The previous state will be initialized to the state of the cubit when the CubitListener is initialized. listenWhen is optional and if omitted, it will default to true. [...]
final, inherited
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited

Methods

createElement() SingleChildStatefulElement
Creates a StatefulElement to manage this widget's location in the tree. [...]
inherited
createState() SingleChildState<CubitListenerBase<B, S>>
Creates the mutable state for this widget at a given location in the tree. [...]
inherited
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. [...]
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
Returns 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, inherited