filter chip sample showing single and multiple chip select

filterChip.dart

import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: _title,
      home: Home(),
    );
  }
}

class ActorFilterEntry {
  const ActorFilterEntry(this.name, this.initials);
  final String name;
  final String initials;
}

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

  @override
  State<Home> createState() => _HomeState();
}

class _HomeState extends State<Home> {
  final List<ActorFilterEntry> _cast = <ActorFilterEntry>[
    const ActorFilterEntry('Aaron Burr', 'AB'),
    const ActorFilterEntry('Alexander Hamilton', 'AH'),
    const ActorFilterEntry('Eliza Hamilton', 'EH'),
    const ActorFilterEntry('James Madison', 'JM'),
  ];

  final List<String> _filters = <String>[];

  Iterable<Widget> get actorWidgets {
    return _cast.map((ActorFilterEntry actor) {
      return Padding(
        padding: const EdgeInsets.all(4.0),
        child: FilterChip(
          avatar: CircleAvatar(child: Text(actor.initials)),
          label: Text(actor.name),
          selected: selected.toLowerCase().contains(actor.name.toLowerCase()),

          /// _filters.contains(actor.name),
          onSelected: (bool value) {
            /// single  chip selection
            setState(() {
              selected = actor.name;
            });
          },
        ),
      );
    });
  }

  Iterable<Widget> get actorWidgetsMultiSelect {
    return _cast.map((ActorFilterEntry actor) {
      return Padding(
        padding: const EdgeInsets.all(4.0),
        child: FilterChip(
          avatar: CircleAvatar(child: Text(actor.initials)),
          label: Text(actor.name),
          selected: _filters.contains(actor.name),
          onSelected: (bool value) {
            setState(() {
              if (value) {
                _filters.add(actor.name);
              } else {
                _filters.removeWhere((String name) {
                  return name == actor.name;
                });
              }
            });
          },
        ),
      );
    });
  }

  String selected = '';
  @override
  Widget build(BuildContext context) {
    return Material(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          const Padding(
            padding: EdgeInsets.symmetric(vertical: 28.0),
            child: Text('Single chip select'),
          ),
          Wrap(
            children: actorWidgets.toList(),
          ),
          const Padding(
            padding: EdgeInsets.symmetric(vertical: 28.0),
            child: Text('mulitple chip select'),
          ),
          Wrap(
            children: actorWidgetsMultiSelect.toList(),
          ),
        ],
      ),
    );
  }
}