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。