WinForm DataGridView 綁定泛型List(List<T>)/ArrayList不顯示的原因和解決，arraylist泛型
背景：無意間遇到了一個不大不小的問題，希望對一些遇到的人有所幫助！
一、問題
WinForm DataGridView 綁定泛型List (List<T>)/ArrayList不顯示，UI
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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、解決方法
其實很簡單，只是很多朋友可能沒有考慮到，因為這壓根不是什麼泛型List或者ArrayList的問題，
只要改代碼：
public class User
{
public int ID;
public string UserName;
public string NickName;
public string Phone;
public string QQ;
}
為：
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、簡單講解
沒定義get、set的是字段，定義了就是屬性了，為了安全性考慮，DataGridView 的數據源綁定只能是被公開了的屬性，而無權訪問字段。很多其他控件也有同樣的情況。
