From a tutorial, an accumulation of widgets from buttons, date-picker, sliders, alert dialog, etc. Some stuff is commented out to reduce the clutter for new widgets. Have fun as sample Dart / Flutter code.

flutter_lots_of_widgets.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'dart:async';

import 'package:flutter/material.dart';

void main() {
  runApp(new MaterialApp(
    home: new MyApp()));
}

class MyApp extends StatefulWidget {
  @override
  _State createState() => new _State();

}

class _State extends State<MyApp> {

  final GlobalKey<ScaffoldState> _scaffoldState = new GlobalKey<ScaffoldState>();

  Future? _showAlertDialog(BuildContext context, String alertMessage) async {
    return showDialog(
        context: context,
        builder: (BuildContext context) { return new AlertDialog(
          title: new Text("title"),
          content: new Text("message"),
          actions: [new TextButton(
              onPressed: () => Navigator.pop(context),
              child: Text("${alertMessage}")
          )],
        );}
    );
  }


  late List<BottomNavigationBarItem> _items;
  String _navValue = "";
  int _index = 0;

  @override
  void initState() {
    super.initState();
    _items = new List.empty(growable: true);
    _items.add(new BottomNavigationBarItem(icon: new Icon(Icons.forward), label: "Forward"));
    _items.add(new BottomNavigationBarItem(icon: new Icon(Icons.backup), label: "Backup"));
    _items.add(new BottomNavigationBarItem(icon: new Icon(Icons.archive), label: "Archive"));
  }

  String _value = "Hello";
  int _counter = 0;
  String _entry = "";

  bool _toggle1 = false;
  bool _toggle2 = false;

  void _onToggle1(bool? toggle) => setState(() => _toggle1 = toggle!);

  void _onToggle2(bool? toggle) => setState(() => _toggle2 = toggle!);

  int _radio1 = 0;
  int _radio2 = 0;

  void _onRadio1(int? radio) => setState(() => _radio1 = radio!);
  void _onRadio2(int? radio) => setState(() => _radio2 = radio!);

  Widget makeRadios() {
    // List list = new List<Widget>.empty(growable: true);
    List<Widget> list = new List.empty(growable: true);
    List titles = ["Casey", "Dawg", "Mobidawg"];

    for (int iRadio=0; iRadio < 3; iRadio++) {
      list.add(Radio(
          key: Key("Radio$iRadio"),
          onChanged: _onRadio1,
          value: iRadio,
          groupValue: _radio1,
      ));

    }

    Column column = new Column(children: list);
    return column;
  }

  Widget makeRadioTiles() {
    // List list = new List<Widget>.empty(growable: true);
    List<Widget> list = new List.empty(growable: true);
    List titles = ["Casey", "Dawg", "Mobidawg"];

    for (int iRadio=0; iRadio < 3; iRadio++) {
      list.add(RadioListTile(
        key: Key("Radio$iRadio"),
        title: Text("${titles[iRadio]}"),
        subtitle: Text("subtitle"),
        onChanged: _onRadio1,
        value: iRadio,
        groupValue: _radio1,
      ));

    }

    Column column = new Column(children: list);
    return column;
  }

  double _sliderValue = 0.50;

  void _onSliderChange(double sliderValue) => setState(() => _sliderValue = sliderValue);


  void _onClick(String value) {
    setState(() {
        // _value = value;
        if( _value == "Hello") {
          _value = "Good-bye";
        } else {
          _value = "Hello";
        }
    });
  }

  void _onChange(String entryText) {
    setState(() => _entry = "Change: $entryText" );
  }

  void _onSubmit(String entryText) {
    setState(() => _entry = "Submit: $entryText" );
  }

  void _add() {
    setState(() {
      _counter++;
    });
  }

  void _subtract() {
    setState(() {
      _counter--;
    });
  }

  /// Date Picker
  ///
  String _date = "";

  Future _pickDate() async {
    DateTime? picked = await showDatePicker(
        context: context,
        initialDate: new DateTime.now(),
        firstDate: new DateTime(2016),
        lastDate: new DateTime(2022)
    );

    if (picked != null) setState(() => _date = picked.toString());
  }

  String _actionValue = "";

  void _onActionButton() => setState(() => (_actionValue = new DateTime.now().toString()));

  int _footerButtonValue = 0;
  void _onFooterButton(footerValue) => setState(() => ( _footerButtonValue = footerValue!));

  void _showBottomActionSheet() {
    showModalBottomSheet<void>(
        context: context,
        builder: (BuildContext context) {
          return new Container(
            height: MediaQuery.of(context).size.height/4.0,
            child: new Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                // new Text("Casey Dog", style: TextStyle(color: Colors.red, fontWeight: FontWeight.bold),),
                new TextButton(onPressed: () => Navigator.pop(context), child: new Text("Casey Dog")),
                new TextButton(onPressed: () => Navigator.pop(context), child: new Text("Yukon Gold")),
                new TextButton(onPressed: () => Navigator.pop(context), child: new Text("Green Acres"))
              ],
            )
          );
        }
    );
  }

  void _showSnackBar() {
    ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: const Text('snack'),
          duration: const Duration(seconds: 1),
          action: SnackBarAction(
            label: 'ACTION',
            onPressed: () { },),
        )
    );
  }




  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      key: _scaffoldState,
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text("Multi-Widget Study App"),
        backgroundColor: Colors.deepOrange,
      ),
        drawer: new Drawer(
            child: new Container(
                padding: EdgeInsets.only(top: 82.0, left: MediaQuery.of(context).size.width/16),
                height: 4.0,
                child: Column(
                    children: <Widget>[
                      new Text("Open"),
                      new ElevatedButton(onPressed: () {
                        setState(() => (_value = "Pop"));
                        Navigator.pop(context);
                      }, child: new Text("Close"))
                    ]
                )
            )
        ),

        bottomNavigationBar: new BottomNavigationBar(
            items: _items,
          fixedColor: Colors.blue,
          currentIndex: _index,
          onTap: (int index) => setState(() {_index = index;}),
        ),
        persistentFooterButtons: [
          new IconButton(icon: new Icon(Icons.style), onPressed: () => _onFooterButton, color: Colors.orangeAccent,),
          new IconButton(icon: new Icon(Icons.accessibility), onPressed: () => _onFooterButton, color: Colors.blueAccent,),
          new IconButton(icon: new Icon(Icons.ac_unit), onPressed: () => _onFooterButton, color: Colors.purpleAccent,),
        ],
        body: new Container(
        color: Colors.white12,
        padding: EdgeInsets.all(6.0),
            child: new Column(
              children: <Widget>[
                Text(_value),
                ElevatedButton(
                  key: Key("Boggle"),
                  onPressed: () => _onClick(_value),
                  child: Text("Toggle"),
                ),
                // Text(_counter.toString()),
                // IconButton(
                //   key: Key("Icon1"),
                //   onPressed: () => _add(),
                //   icon: new Icon(Icons.add),
                // ),
                // IconButton(
                //   key: Key("Icon2"),
                //   onPressed: () => _subtract(),
                //   icon: new Icon(Icons.remove),
                // ),
                // Text(_entry),
                // TextField(
                //   key: Key("Entry"),
                //   autofocus: true,
                //   keyboardType: TextInputType.emailAddress,
                //   decoration: new InputDecoration(
                //     labelText: '',
                //     hintText: 'Enter your email abddress ...',
                //     icon: new Icon(Icons.email),
                //   ),
                //   onSubmitted: _onSubmit,
                //   onChanged: _onChange,
                // ),
                // // --- check-boxes without any title, etc.
                // // Checkbox(key: Key("Checkbox1"), value: _toggle1, onChanged: _onToggle1),
                // // Checkbox(key: Key("Checkbox2"), value: _toggle2, onChanged: _onToggle2)
                // CheckboxListTile(
                //     value: _toggle1,
                //     onChanged: _onToggle1,
                //   title: Text("Toggle this box."),
                //   controlAffinity: ListTileControlAffinity.leading,
                // ),
                // CheckboxListTile(
                //   value: _toggle2,
                //   onChanged: _onToggle2,
                //   title: Text("Toggle this box."),
                //   controlAffinity: ListTileControlAffinity.leading,
                //   subtitle: Text("subtitle"),
                //   secondary: new Icon(Icons.access_time),
                //   activeColor: Colors.redAccent,
                // )
                makeRadioTiles(),
                new Text("Percent ${(_sliderValue*100.0).round()}%"),
                new Slider(key: Key("slider1"), value: _sliderValue, onChanged: _onSliderChange,),
                new Center(
                  child: new Column(
                    children: <Widget>[
                      Text("$_date"),
                      ElevatedButton(onPressed: _pickDate, child: new Text("Pick Date"))
                    ]
                  ),
                ),
                // Text("$_actionValue"),
                // ElevatedButton(onPressed: (true) ? _showBottomActionSheet : _showSnackBar, child: new Text((true) ? "Action Sheet" : "Snack bar"))
                Text("$_actionValue"),
                ElevatedButton(
                    onPressed: () => _showAlertDialog(context, "alert message"),
                    child: new Text("Alert Dialog"))
              ],
            ),
        ),
      floatingActionButton: new FloatingActionButton(
          mini: true,
          backgroundColor: Colors.deepPurple,
          onPressed: _onActionButton,
          child: new Icon(Icons.access_alarm)
      )
    );
  }

}