KeyboardListener class Null safety

A widget that calls a callback whenever the user presses or releases a key on a keyboard.

A KeyboardListener is useful for listening to key events and hardware buttons that are represented as keys. Typically used by games and other apps that use keyboards for purposes other than text entry.

For text entry, consider using a EditableText, which integrates with on-screen keyboards and input method editors (IMEs).

The KeyboardListener is different from RawKeyboardListener in that KeyboardListener uses the newer HardwareKeyboard API, which is preferable.

See also:

Inheritance

Constructors

KeyboardListener({Key? key, required FocusNode focusNode, bool autofocus = false, bool includeSemantics = true, ValueChanged<KeyEvent>? onKeyEvent, required Widget child})
Creates a widget that receives keyboard events.
const

Properties

autofocus → bool
True if this widget will be selected as the initial focus when no other node in its scope is currently focused.
final
child → Widget
The widget below this widget in the tree.
final
focusNode → FocusNode
Controls whether this widget has keyboard focus.
final
hashCode → int
The hash code for this object.
nonVirtual">@nonVirtualread-onlyinherited
includeSemantics → bool
Include semantics information in this widget.
final
key → Key?
Controls how one widget replaces another widget in the tree.
finalinherited
onKeyEvent → ValueChanged<KeyEvent>?
Called whenever this widget receives a keyboard event.
final
runtimeType → Type
A representation of the runtime type of the object.
read-onlyinherited

Methods

build(BuildContext context) → Widget
Describes the part of the user interface represented by this widget.
override
createElement() → StatelessElement
Creates a StatelessElement to manage this widget's location in the tree.
inherited
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.
override
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