背景：无意间遇到了一个不大不小的问题，希望对一些遇到的人有所帮助！

一、问题

WinForm DataGridView 绑定泛型List (List<T>)/ArrayList不显示，UI

代码如下：

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.OleDb;
using System.IO;
using System.Windows.Forms;namespace WindowsFormsApplication1
{public delegate T BorrowReader<out T>(IDataReader reader);public partial class FormMain : Form{public FormMain(){InitializeComponent();}private List<User> GetUsers(IDataReader reader){var list = new List<User>();while (reader.Read()){list.Add(new User(){ID = reader.GetInt32(reader.GetOrdinal("ID")),UserName = reader.GetString(reader.GetOrdinal("UserName")),NickName = reader.GetString(reader.GetOrdinal("NickName")),Phone = reader.GetString(reader.GetOrdinal("Phone")),QQ = reader.GetString(reader.GetOrdinal("QQ")),});}return list;}private void btnTest_Click(object sender, EventArgs e){dataGridView1.AutoGenerateColumns = false;var list = MyDb.LendReader("select * from Users where 0=0", GetUsers);dataGridView1.DataSource = list;}}public class User{public int ID;public string UserName;public string NickName;public string Phone;public string QQ;}public class MyDb{public static T LendReader<T>(string sql, BorrowReader<T> borrowReader){using (OleDbConnection connection = CreateConnection()){connection.Open();OleDbCommand c = new OleDbCommand(sql, connection);OleDbDataReader r = c.ExecuteReader();return borrowReader(r);}}private static OleDbConnection CreateConnection(){string dbName = Path.Combine(Application.StartupPath, "MyData.mdb");OleDbConnection c = new OleDbConnection{ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + dbName};return c;}}
}

二、解决方法

其实很简单，只是很多朋友可能没有考虑到，因为这压根不是什么泛型List或者ArrayList的问题，

只要改代码：

    public class User{public int ID;public string UserName;public string NickName;public string Phone;public string QQ;}

为：

    public class User{public int ID{ get; set; }public string UserName { get; set; }public string NickName { get; set; }public string Phone { get; set; }public string QQ { get; set; } }

就好了

三、简单讲解

没定义get、set的是字段，定义了就是属性了，为了安全性考虑，DataGridView 的数据源绑定只能是被公开了的属性，而无权访问字段。很多其他控件也有同样的情况。