===========ValueObject.cs============
using System;
using System.Collections.Generic;
using System.Text;
namespace psms.util
{
     class ValueObject
     {
         private string value;
         private string text;
         public ValueObject(string v, string t)
         {
             this.value = v;
             this.text = t;
         }
         public string Value
         {
             get { return this.value;}
         }
         public string Text
         {
             get { return this.text; }
         }
     }
}
===============绑定数据===============
this.combIn_Acc.Items.Add(new util.ValueObject("", ""));
this.combIn_Acc.Items.Add(new util.ValueObject("0","未做帐"));
this.combIn_Acc.Items.Add(new util.ValueObject("1", "已做帐"));
             
this.combIn_Acc.ValueMember = "value";
this.combIn_Acc.DisplayMember = "text";
this.combIn_Acc.SelectedIndex = 0;
================取值==================
if (this.combIn_Acc.SelectedIndex >= 0)
{
    if (((util.ValueObject)this.combIn_Acc.SelectedItem).Value.ToString() != "")
    {
        condition.Append(" and in_acc = ").Append(((util.ValueObject)this.combIn_Acc.SelectedItem).Value.ToString()).Append(" ");
    }
}
不知道为什么this.combIn_Acc.SelectedValue总是报空指针异常,想不明白,换了上面的取值方法终于可行了