[Visual C# 2017][WPF] WpfMVVMSample

Commands\DelegateCommand.cs

using System;
using System.Windows.Input;

namespace WpfMVVMSample.Commands
{
    public class DelegateCommand : ICommand
    {
        private Action _execute;
        private Func<bool> _canExecute;

        public DelegateCommand(Action execute, Func<bool> canExecute)
        {
            _execute = execute;
            _canExecute = canExecute;
        }

        public void Execute(object parameter)
        {
            _execute();
        }

        public bool CanExecute(object parameter)
        {
            return _canExecute();
        }

        public event EventHandler CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }
    }
}

MainWindow.xaml

<Window x:Class="WpfMVVMSample.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfMVVMSample"
        mc:Ignorable="d"
        xmlns:vm="clr-namespace:WpfMVVMSample.ViewModels"
        Title="MainWindow" Height="350" Width="525">

    <Window.DataContext>
        <vm:MainViewModel />
    </Window.DataContext>

    <Window.InputBindings>
        <KeyBinding Gesture="Enter" 
            Command="{Binding Path=ShowSelectedItemCommand}" />
    </Window.InputBindings>

    <Grid>
        <ListBox ItemsSource="{Binding Path=Items}"
            SelectedItem="{Binding Path=SelectedItem}">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <TextBlock>
                        <TextBlock.Text>
                            <MultiBinding StringFormat="{}{0},{1}">
                                <Binding Path="Name" />
                                <Binding Path="Age" />
                            </MultiBinding>
                        </TextBlock.Text>
                    </TextBlock>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </Grid>
</Window>

MainWindow.xaml.cs

using System.Windows;

namespace WpfMVVMSample
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
    }
}

Models\Person.cs

namespace WpfMVVMSample.Models
{
    public class Person
    {
        public string Name { get; set; }
        public int Age { get; set; }

        public Person(string name, int age)
        {
            this.Name = name;
            this.Age = age;
        }
    }
}

ViewModels\MainViewModel.cs

using System.Windows;

using System.ComponentModel;  // INotifyPropertyChanged
using System.Collections.ObjectModel;  // ObservableCollection

using WpfMVVMSample.Commands;
using WpfMVVMSample.Models;

namespace WpfMVVMSample.ViewModels
{
    public class MainViewModel : INotifyPropertyChanged
    {
        // ---------------------------------------------------------------------
        // プロパティ - リスト

        private ObservableCollection<Person> _items;
        public ObservableCollection<Person> Items
        {
            get { return _items; }
            set
            {
                _items = value;
                this.OnPropertyChanged(nameof(Items));
            }
        }

        public Person SelectedItem { get; set; }

        // ---------------------------------------------------------------------
        // プロパティ - コマンド

        private DelegateCommand _showSelectedItemCommand;
        public DelegateCommand ShowSelectedItemCommand
        {
            get
            {
                if (_showSelectedItemCommand == null)
                {
                    _showSelectedItemCommand = new DelegateCommand(
                        () => this.DoShowSelectedItem(),
                        () => this.SelectedItem != null
                     );
                }
                return _showSelectedItemCommand;
            }
        }

        private void DoShowSelectedItem()
        {
            string message = string.Format("{0},{1}",
                this.SelectedItem.Name, this.SelectedItem.Age);
            MessageBox.Show(message);
        }

        // ---------------------------------------------------------------------
        // コンストラクタ

        public MainViewModel()
        {
            // 動作テスト用データ
            this.Items = new ObservableCollection<Person>();
            this.Items.Add(new Person("太郎", 39));
            this.Items.Add(new Person("花子", 34));
            this.Items.Add(new Person("次郎", 28));
            this.Items.Add(new Person("良子", 22));
            this.Items.Add(new Person("三郎", 15));
        }

        // ---------------------------------------------------------------------
        // インターフェースの実装 - INotifyPropertyChanged

        public event PropertyChangedEventHandler PropertyChanged;

        private void OnPropertyChanged(string name)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
        }
    }
}