防止将剪贴板中的重复项目添加到ListBox

using System;
using System.Collections.Generic;
using System.Windows.Forms;

public class UniqueListBox : ListBox
{
    protected override void OnPaste(EventArgs e)
    {
        // 获取剪贴板中的文本
        string clipboardText = Clipboard.GetText();

        // 将文本按行分割成项目列表
        string[] items = clipboardText.Split(new[] { '\n', '\r' }, StringSplitOptions.RemoveEmptyEntries);

        // 检查并添加唯一项目
        foreach (string item in items)
        {
            if (!this.Items.Contains(item))
            {
                this.Items.Add(item);
            }
        }

        base.OnPaste(e);
    }
}

public class MainForm : Form
{
    private UniqueListBox listBox;

    public MainForm()
    {
        listBox = new UniqueListBox();
        listBox.Dock = DockStyle.Fill;
        this.Controls.Add(listBox);
    }

    [STAThread]
    static void Main()
    {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        Application.Run(new MainForm());
    }
}