AlertDialog class Null safety

A Material Design alert dialog.

An alert dialog (also known as a basic 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.

This snippet shows a method in a State which, when called, displays a dialog box and returns a Future that completes when the dialog is dismissed.

Future<void> _showMyDialog() async {
  return showDialog<void>(
    context: context,
    barrierDismissible: false, // user must tap button!
    builder: (BuildContext context) {
      return AlertDialog(
        title: const Text('AlertDialog Title'),
        content: SingleChildScrollView(
          child: ListBody(
            children: const <Widget>[
              Text('This is a demo alert dialog.'),
              Text('Would you like to approve of this message?'),
            ],
          ),
        ),
        actions: <Widget>[
          TextButton(
            child: const Text('Approve'),
            onPressed: () {
              Navigator.of(context).pop();
            },
          ),
        ],
      );
    },
  );
}

This demo shows a TextButton which when pressed, calls showDialog. When called, this method displays a Material dialog above the current contents of the app and returns a Future that completes when the dialog is dismissed.

To create a local project with this code sample, run:
flutter create --sample=material.AlertDialog.2 mysample

This sample shows the creation of AlertDialog, as described in: https://m3.material.io/components/dialogs/overview

To create a local project with this code sample, run:
flutter create --sample=material.AlertDialog.3 mysample

Constructors

AlertDialog({Key? key, Widget? icon, EdgeInsetsGeometry? iconPadding, Color? iconColor, Widget? title, EdgeInsetsGeometry? titlePadding, TextStyle? titleTextStyle, Widget? content, EdgeInsetsGeometry? contentPadding, TextStyle? contentTextStyle, List<Widget>? actions, EdgeInsetsGeometry? actionsPadding, MainAxisAlignment? actionsAlignment, OverflowBarAlignment? actionsOverflowAlignment, VerticalDirection? actionsOverflowDirection, double? actionsOverflowButtonSpacing, EdgeInsetsGeometry? buttonPadding, Color? backgroundColor, double? elevation, String? semanticLabel, EdgeInsets insetPadding = _defaultInsetPadding, Clip clipBehavior = Clip.none, ShapeBorder? shape, AlignmentGeometry? alignment, bool scrollable = false}): Creates an alert dialog.
const

Properties

actions → List<Widget>?: The (optional) set of actions that are displayed at the bottom of the dialog with an OverflowBar.
final
actionsAlignment → MainAxisAlignment?: Defines the horizontal layout of the actions according to the same rules as for Row.mainAxisAlignment.
final
actionsOverflowAlignment → OverflowBarAlignment?: The horizontal alignment of actions within the vertical "overflow" layout.
final
actionsOverflowButtonSpacing → double?: The spacing between actions when the OverflowBar switches to a column layout because the actions don't fit horizontally.
final
actionsOverflowDirection → VerticalDirection?: The vertical direction of actions if the children overflow horizontally.
final
actionsPadding → EdgeInsetsGeometry?: Padding around the set of actions at the bottom of the dialog.
final
alignment → AlignmentGeometry?: How to align the Dialog.
final
backgroundColor → Color?: The background color of the surface of this Dialog.
final
buttonPadding → EdgeInsetsGeometry?: The padding that surrounds each button in actions.
final
clipBehavior → Clip: Controls how the contents of the dialog are clipped (or not) to the given shape.
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
contentTextStyle → TextStyle?: Style for the text in the content of this AlertDialog.
final
elevation → double?: The z-coordinate of this Dialog.
final
hashCode → int: The hash code for this object.
nonVirtual">@nonVirtualread-onlyinherited
icon → Widget?: An optional icon to display at the top of the dialog.
final
iconColor → Color?: Color for the Icon in the icon of this AlertDialog.
final
iconPadding → EdgeInsetsGeometry?: Padding around the icon.
final
insetPadding → EdgeInsets: The amount of padding added to MediaQueryData.viewInsets on the outside of the dialog. This defines the minimum space between the screen's edges and the dialog.
final
key → Key?: Controls how one widget replaces another widget in the tree.
finalinherited
runtimeType → Type: A representation of the runtime type of the object.
read-onlyinherited
scrollable → bool: Determines whether the title and content widgets are wrapped in a scrollable.
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, below the (optional) icon.
final
titlePadding → EdgeInsetsGeometry?: Padding around the title.
final
titleTextStyle → TextStyle?: Style for the text in the title of this AlertDialog.
final

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.
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: 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

Flutter
material
AlertDialog class

AlertDialog class Null safety

Constructors

Properties

Methods

Operators

material library