C#(WinForm) ComboBox和ListBox添加项及设置默认选择项

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace WinListItem
{
  /// <summary>
  /// 选择项类，用于ComboBox或者ListBox添加项
  /// </summary>
  public class ListItem
  {
    private string id = string.Empty;
    private string name = string.Empty;
    public ListItem(string sid, string sname)
    {
      id = sid;
      name = sname;
    }
    public override string ToString()
    {
      return this.name;
    }
    public string ID
    {
      get
      {
        return this.id;
      }
      set
      {
        this.id = value;
      }
    }
    public string Name
    {
      get
      {
        return this.name;
      }
      set
      {
        this.name = value;
      }
    }
  }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WinListItem
{
  public partial class MainFrm : Form
  {
    public MainFrm()
    {
      InitializeComponent();
    }

    private void btnOk_Click(object sender, EventArgs e)
    {
      ListItem listItem = comboBox1.SelectedItem as ListItem;
      MessageBox.Show(listItem.ID + "," + listItem.Name);
    }

    private void MainFrm_Load(object sender, EventArgs e)
    {
      //添加项，Web控件DropDownList有对应的ListItem
      ListItem listItem0 = new ListItem("0", "选项零");
      ListItem listItem1 = new ListItem("1", "选项一");
      ListItem listItem2 = new ListItem("2", "选项二");
      comboBox1.Items.Add(listItem0);
      comboBox1.Items.Add(listItem1);
      comboBox1.Items.Add(listItem2);
      //设置默认选择项，DropDownList会默认选择第一项。
      comboBox1.SelectedIndex = 0;//设置第一项为默认选择项。
      comboBox1.SelectedItem = listItem1;//设置指定的项为默认选择项
    }
  }
}