AlertDialog class
A material design alert dialog.
An alert dialog informs the user about situations that require acknowledgement. An alert dialog has an optional title and an optional list of actions. The title is displayed above the content and the actions are displayed below the content.
If the content is too large to fit on the screen vertically, the dialog will display the title and the actions and let the content overflow, which is rarely desired. Consider using a scrolling widget for content, such as SingleChildScrollView, to avoid overflow. (However, be aware that since AlertDialog tries to size itself using the intrinsic dimensions of its children, widgets such as ListView, GridView, and CustomScrollView, which use lazy viewports, will not work. If this is a problem, consider using Dialog directly.)
For dialogs that offer the user a choice between several options, consider using a SimpleDialog.
Typically passed as the child widget to showDialog, which displays the dialog.
Future<void> _neverSatisfied() async {
return showDialog<void>(
context: context,
barrierDismissible: false, // user must tap button!
builder: (BuildContext context) {
return AlertDialog(
title: Text('Rewind and remember'),
content: SingleChildScrollView(
child: ListBody(
children: <Widget>[
Text('You will never be satisfied.'),
Text('You\’re like me. I’m never satisfied.'),
],
),
),
actions: <Widget>[
FlatButton(
child: Text('Regret'),
onPressed: () {
Navigator.of(context).pop();
},
),
],
);
},
);
}
See also:
- SimpleDialog, which handles the scrolling of the contents but has no actions.
- Dialog, on which AlertDialog and SimpleDialog are based.
- showDialog, which actually displays the dialog and returns its result.
- material.google.com/components/dialogs.html#dialogs-alerts
- Inheritance
- Object
- Diagnosticable
- DiagnosticableTree
- Widget
- StatelessWidget
- AlertDialog
Constructors
-
AlertDialog({Key key, Widget title, EdgeInsetsGeometry titlePadding, Widget content, EdgeInsetsGeometry contentPadding: const EdgeInsets.fromLTRB(24.0, 20.0, 24.0, 24.0), List<
Widget> actions, String semanticLabel, ShapeBorder shape }) -
Creates an alert dialog. [...]
const
Properties
-
actions
→ List<
Widget> -
The (optional) set of actions that are displayed at the bottom of the
dialog. [...]
final
- content → Widget
-
The (optional) content of the dialog is displayed in the center of the
dialog in a lighter font. [...]
final
- contentPadding → EdgeInsetsGeometry
-
Padding around the content. [...]
final
- semanticLabel → String
-
The semantic label of the dialog used by accessibility frameworks to
announce screen transitions when the dialog is opened and closed. [...]
final
- shape → ShapeBorder
-
The shape of this dialog's border. [...]
final
- title → Widget
-
The (optional) title of the dialog is displayed in a large font at the top
of the dialog. [...]
final
- titlePadding → EdgeInsetsGeometry
-
Padding around the title. [...]
final
- hashCode → int
-
The hash code for this object. [...]
read-only, inherited
- key → Key
-
Controls how one widget replaces another widget in the tree. [...]
final, inherited
- runtimeType → Type
-
A representation of the runtime type of the object.
read-only, inherited
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, 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 toStringDeep. [...]
inherited
-
toString(
{DiagnosticLevel minLevel: DiagnosticLevel.debug }) → 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 ==(
dynamic other) → bool -
The equality operator. [...]
inherited