alert_dialog_actions_alignment.dart

import 'package:flutter/material.dart';

class Home extends StatefulWidget {
  const Home({ Key? key }) : super(key: key);

  @override
  _HomeState createState() => _HomeState();
}

class _HomeState extends State<Home> {
  MainAxisAlignment? _alignment;

  @override
  Widget build(BuildContext context) {
    const List<MainAxisAlignment?> alignments = <MainAxisAlignment?>[
      null,
      MainAxisAlignment.start,
      MainAxisAlignment.center,
      MainAxisAlignment.end,
      MainAxisAlignment.spaceBetween,
      MainAxisAlignment.spaceAround,
      MainAxisAlignment.spaceEvenly,
    ];

    return Scaffold(
      appBar: AppBar(
        title: Text('AlertDialog actionsAlignment'),
        actions: <Widget>[
          PopupMenuButton<MainAxisAlignment?>(
            child: Padding(
              padding: EdgeInsetsDirectional.only(end: 8),
              child: Icon(Icons.menu)
            ),
            onSelected: (MainAxisAlignment? result) {
              setState(() { _alignment = result; });
            },
            itemBuilder: (BuildContext context) {
              return alignments.map((MainAxisAlignment? alignment) {
                return PopupMenuItem<MainAxisAlignment?>(
                  value: alignment,
                  child: Text(alignment == null ? 'default' : '$alignment'.substring(18)),
                );
              }).toList();
            },
          ),
        ],
      ),
      body: AlertDialog(
        actionsAlignment: _alignment,
        title: Text('AlertDialog: $_alignment'),
        content: SingleChildScrollView(
          child: ListBody(
            children: <Widget>[
              Text('This is an AlertDialog.'),
              SizedBox(height: 8),
              Text('Select different values for actionsAlignment'),
              Text('from the AppBar dropdown menu on the right.'),
            ],
          ),
        ),
        actions: <String>['One', 'Two', 'Free', 'Four'].map<Widget>((String text) {
          return TextButton(
            child: Text(text),
            onPressed: () {
              Navigator.of(context).pop();
            },
          );
        }).toList(),
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: Home(),
    // The "DEBUG" banner obscures the menu button.
    debugShowCheckedModeBanner: false,
  ));
}