SimpleDialog class Null safety

A simple Material Design dialog.

A simple dialog offers the user a choice between several options. A simple dialog has an optional title that is displayed above the choices.

Choices are normally represented using SimpleDialogOption widgets. If other widgets are used, see contentPadding for notes regarding the conventions for obtaining the spacing expected by Material Design.

For dialogs that inform the user about a situation, consider using an AlertDialog.

Typically passed as the child widget to showDialog, which displays the dialog.

In this example, the user is asked to select between two options. These options are represented as an enum. The showDialog method here returns a Future that completes to a value of that enum. If the user cancels the dialog (e.g. by hitting the back button on Android, or tapping on the mask behind the dialog) then the future completes with the null value.

The return value in this example is used as the index for a switch statement. One advantage of using an enum as the return value and then using that to drive a switch statement is that the analyzer will flag any switch statement that doesn't mention every value in the enum.

Future<void> _askedToLead() async {
  switch (await showDialog<Department>(
    context: context,
    builder: (BuildContext context) {
      return SimpleDialog(
        title: const Text('Select assignment'),
        children: <Widget>[
          SimpleDialogOption(
            onPressed: () { Navigator.pop(context, Department.treasury); },
            child: const Text('Treasury department'),
          ),
          SimpleDialogOption(
            onPressed: () { Navigator.pop(context, Department.state); },
            child: const Text('State department'),
          ),
        ],
      );
    }
  )) {
    case Department.treasury:
      // Let's go.
      // ...
    break;
    case Department.state:
      // ...
    break;
    case null:
      // dialog dismissed
    break;
  }
}

Constructors

SimpleDialog({Key? key, Widget? title, EdgeInsetsGeometry titlePadding = const EdgeInsets.fromLTRB(24.0, 24.0, 24.0, 0.0), TextStyle? titleTextStyle, List<Widget>? children, EdgeInsetsGeometry contentPadding = const EdgeInsets.fromLTRB(0.0, 12.0, 0.0, 16.0), Color? backgroundColor, double? elevation, String? semanticLabel, EdgeInsets insetPadding = _defaultInsetPadding, Clip clipBehavior = Clip.none, ShapeBorder? shape, AlignmentGeometry? alignment}): Creates a simple dialog.
const

Properties

alignment → AlignmentGeometry?: The shape of this dialog's border.
final
backgroundColor → Color?: The background color of the surface of this Dialog.
final
children → List<Widget>?: The (optional) content of the dialog is displayed in a SingleChildScrollView underneath the title.
final
clipBehavior → Clip: Controls how the contents of the dialog are clipped (or not) to the given shape.
final
contentPadding → EdgeInsetsGeometry: Padding around the content.
final
elevation → double?: The z-coordinate of this Dialog.
final
hashCode → int: The hash code for this object.
nonVirtual">@nonVirtualread-onlyinherited
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
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
titleTextStyle → TextStyle?: Style for the text in the title of this SimpleDialog.
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
SimpleDialog class

SimpleDialog class Null safety

Constructors

Properties

Methods

Operators

material library