[ASP.NET]利用List<T>的Sort()、Find()、FindAll()、Exist()來解決一些問題

2009-05-28

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ASP.NET

最近寫案子常常用到List,這個東西還真好用

最近寫案子常常用到List<T>,這個東西還真好用

因為它有下列東西：

List<T>.Sort() → 排序T

List<T>.Find() → 找出一個T

List<T>.FindAll() →找出多個T

List<T>.Exist() →判斷T是否存在

小弟就寫個範例介紹這些東西吧..

GenericList.aspx

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="GenericList.aspx.cs" Inherits="GenericList" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>GenericList</title> </head> <body> <form id="form1" runat="server"> <div> 原始資料： <asp:GridView ID="GridView1" runat="server"> </asp:GridView> </div> </form> </body> </html>

GenericList.aspx.cs

using System; using System.Collections.Generic; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; public partial class GenericList : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { List<Person> lstPerson = new List<Person>(); lstPerson.Add(new Person(1, "puma", 10)); lstPerson.Add(new Person(2, "F6 Team", 20)); lstPerson.Add(new Person(3, "ASP.NET", 30)); lstPerson.Add(new Person(4, "Dotblogs", 40)); //原始資料顯示在GridView上 this.GridView1.DataSource = lstPerson; this.GridView1.DataBind(); //List<T>.Find() //找出Name='puma'的Person Response.Write("找出Name='puma'的Person→ "); Response.Write(lstPerson.Find(delegate(Person p) { return p.Name == "puma"; }).ToString() + "<p>"); //List<T>.FindAll() //找出Age>10的數目 Response.Write("找出Age>10的數目→ "); Response.Write(lstPerson.FindAll(delegate(Person p) { return p.Age > 10; }).Count.ToString() + "<p>"); //List<T>.Exists() //檢查Name='F6'是否存在 Response.Write("檢查Name='F6'是否存在→ "); Response.Write(lstPerson.Exists(delegate(Person p) { return p.Name == "F6"; }).ToString() + "<p>"); //List<T>.Sort() //依Name升冪排序 Response.Write("<p>依Name升冪排序↑<br/>"); lstPerson.Sort(delegate(Person p1, Person p2) { return Comparer<string>.Default.Compare(p1.Name, p2.Name); }); foreach (Person p in lstPerson) { Response.Write(p.ToString() + "<br/>"); } //List<T>.Sort() //依Name降冪排序 Response.Write("<p>依Name降冪排序↓<br/>"); lstPerson.Sort(delegate(Person p1, Person p2) { return Comparer<string>.Default.Compare(p2.Name, p1.Name); }); foreach (Person p in lstPerson) { Response.Write(p.ToString() + "<br/>"); } } } public class Person { private int _ID; private string _Name; private int _Age; public Person(int ID, string Name, int Age) { _ID = ID; _Name = Name; _Age = Age; } public int ID { set { _ID = value; } get { return _ID; } } public string Name { set { _Name = value; } get { return _Name; } } public int Age { set { _Age = value; } get { return _Age; } } public override string ToString() { return string.Format("ID：{0}，Name：{1}，Age：{2}", _ID, _Name, _Age); } }

執行結果：

參考網址：
http://blogs.msdn.com/kcwalina/archive/2004/06/22/162533.aspx
http://www.dotblogs.com.tw/chhuang/archive/2008/05/08/3908.aspx

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