WPF 列表框 - 空列表显示消息

使用WPF（Windows Presentation Foundation）的列表框控件可以方便地显示和管理数据。在某些情况下，列表框可能是空的，这时我们希望能够显示一条消息来提示用户当前列表为空。本文将介绍如何在空列表中显示消息，并提供一个案例代码来演示该功能。

xaml
    
        
            
        
    

csharp
private ObservableCollection _myData;
public ObservableCollection MyData
{
    get { return _myData; }
    set
    {
        _myData = value;
        if (_myData == null || _myData.Count == 0)
        {
            _myData = new ObservableCollection { "EmptyMessage" };
        }
        else if (_myData.Contains("EmptyMessage"))
        {
            _myData.Remove("EmptyMessage");
        }
        OnPropertyChanged(nameof(MyData));
    }
}

xaml
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Empty ListBox Message" Height="300" Width="400">
    
        
            
                
                    
                
            
        
    

csharp
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Windows;
namespace EmptyListBoxMessage
{
    public partial class MainWindow : Window, INotifyPropertyChanged
    {
        private ObservableCollection _myData;
        public ObservableCollection MyData
        {
            get { return _myData; }
            set
            {
                _myData = value;
                if (_myData == null || _myData.Count == 0)
                {
                    _myData = new ObservableCollection { "EmptyMessage" };
                }
                else if (_myData.Contains("EmptyMessage"))
                {
                    _myData.Remove("EmptyMessage");
                }
                OnPropertyChanged(nameof(MyData));
            }
        }
        public MainWindow()
        {
            InitializeComponent();
            DataContext = this;
            // 模拟数据源为空
            MyData = new ObservableCollection();
        }
        public event PropertyChangedEventHandler PropertyChanged;
        protected virtual void OnPropertyChanged(string propertyName)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}