AlertDialog class Null safety

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.

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: Text('AlertDialog Title'),
        content: SingleChildScrollView(
          child: ListBody(
            children: <Widget>[
              Text('This is a demo alert dialog.'),
              Text('Would you like to approve of this message?'),
        actions: <Widget>[
            child: Text('Approve'),
            onPressed: () {

See also:



AlertDialog({Key? key, Widget? title, EdgeInsetsGeometry? titlePadding, TextStyle? titleTextStyle, Widget? content, EdgeInsetsGeometry contentPadding: const EdgeInsets.fromLTRB(24.0, 20.0, 24.0, 24.0), TextStyle? contentTextStyle, List<Widget>? actions, EdgeInsetsGeometry actionsPadding:, VerticalDirection? actionsOverflowDirection, double? actionsOverflowButtonSpacing, EdgeInsetsGeometry? buttonPadding, Color? backgroundColor, double? elevation, String? semanticLabel, EdgeInsets insetPadding: _defaultInsetPadding, Clip clipBehavior: Clip.none, ShapeBorder? shape, bool scrollable: false})
Creates an alert dialog. [...]


actions List<Widget>?
The (optional) set of actions that are displayed at the bottom of the dialog. [...]
actionsOverflowButtonSpacing double?
The spacing between actions when the button bar overflows. [...]
actionsOverflowDirection VerticalDirection?
The vertical direction of actions if the children overflow horizontally. [...]
actionsPadding EdgeInsetsGeometry
Padding around the set of actions at the bottom of the dialog. [...]
backgroundColor Color?
The background color of the surface of this Dialog. [...]
buttonPadding EdgeInsetsGeometry?
The padding that surrounds each button in actions. [...]
clipBehavior Clip
Controls how the contents of the dialog are clipped (or not) to the given shape. [...]
content Widget?
The (optional) content of the dialog is displayed in the center of the dialog in a lighter font. [...]
contentPadding EdgeInsetsGeometry
Padding around the content. [...]
contentTextStyle TextStyle?
Style for the text in the content of this AlertDialog. [...]
elevation double?
The z-coordinate of this Dialog. [...]
hashCode int
The hash code for this object. [...]
@nonVirtual, read-only, inherited
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. [...]
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
scrollable bool
Determines whether the title and content widgets are wrapped in a scrollable. [...]
@Deprecated('Set scrollable to `true`. This parameter will be removed and ' 'was introduced to migrate AlertDialog to be scrollable by ' 'default. For more information, see ' ' ' 'This feature was deprecated after v1.13.2.'), final
semanticLabel String?
The semantic label of the dialog used by accessibility frameworks to announce screen transitions when the dialog is opened and closed. [...]
shape ShapeBorder?
The shape of this dialog's border. [...]
title Widget?
The (optional) title of the dialog is displayed in a large font at the top of the dialog. [...]
titlePadding EdgeInsetsGeometry?
Padding around the title. [...]
titleTextStyle TextStyle?
Style for the text in the title of this AlertDialog. [...]


build(BuildContext context) Widget
Describes the part of the user interface represented by this widget. [...]
createElement() StatelessElement
Creates a StatelessElement to manage this widget's location in the tree. [...]
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. [...]
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed. [...]
toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) DiagnosticsNode
Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep. [...]
toString({DiagnosticLevel minLevel:}) String
A string representation of this object. [...]
toStringDeep({String prefixLineOne: '', String? prefixOtherLines, DiagnosticLevel minLevel: DiagnosticLevel.debug}) String
Returns a string representation of this node and its descendants. [...]
toStringShallow({String joiner: ', ', DiagnosticLevel minLevel: DiagnosticLevel.debug}) String
Returns a one-line detailed description of the object. [...]
toStringShort() String
A short, textual description of this widget.


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