利用List的Sort()、Find()、FindAll()、Exist()來解決一些問題

原文地址:

http://www.dotblogs.com.tw/puma/archive/2009/05/28/asp.net-generic-list-sort-find-findall-exsit.aspx#12190

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

01<%@ Page Language="C#" AutoEventWireup="true" CodeFile="GenericList.aspx.cs" Inherits="GenericList" %>
02 
03<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
04 
06<head runat="server">
07    <title>GenericList</title>
08</head>
09<body>
10    <form id="form1" runat="server">
11    <div>
12        原始資料：
13        <asp:GridView ID="GridView1" runat="server">
14        </asp:GridView>
15    </div>
16    </form>
17</body>
18</html>

GenericList.aspx.cs

001using System;
002using System.Collections.Generic;
003using System.Web;
004using System.Web.UI;
005using System.Web.UI.WebControls;
006 
007public partial class GenericList : System.Web.UI.Page
008{
009 
010    protected void Page_Load(object sender, EventArgs e)
011    {
012        List<Person> lstPerson = new List<Person>();
013        lstPerson.Add(new Person(1, "puma", 10));
014        lstPerson.Add(new Person(2, "F6 Team", 20));
015        lstPerson.Add(new Person(3, "ASP.NET", 30));
016        lstPerson.Add(new Person(4, "Dotblogs", 40));
017 
018        //原始資料顯示在GridView上
019        this.GridView1.DataSource = lstPerson;
020        this.GridView1.DataBind();
021 
022 
023 
024        //List<T>.Find()
025        //找出Name='puma'的Person
026        Response.Write("找出Name='puma'的Person→ ");
027        Response.Write(lstPerson.Find(delegate(Person p) { return p.Name == "puma"; }).ToString() + "<p>");
028 
029 
030 
031        //List<T>.FindAll()
032        //找出Age>10的數目
033        Response.Write("找出Age>10的數目→ ");
034        Response.Write(lstPerson.FindAll(delegate(Person p) { return p.Age > 10; }).Count.ToString() + "<p>");
035 
036 
037 
038        //List<T>.Exists()
039        //檢查Name='F6'是否存在
040        Response.Write("檢查Name='F6'是否存在→ ");
041        Response.Write(lstPerson.Exists(delegate(Person p) { return p.Name == "F6"; }).ToString() + "<p>");
042 
043 
044 
045        //List<T>.Sort()
046        //依Name升冪排序
047        Response.Write("<p>依Name升冪排序↑<br/>");
048        lstPerson.Sort(delegate(Person p1, Person p2) { return Comparer<string>.Default.Compare(p1.Name, p2.Name); });
049        foreach (Person p in lstPerson)
050        {
051            Response.Write(p.ToString() + "<br/>");
052        }
053 
054 
055 
056        //List<T>.Sort()
057        //依Name降冪排序
058        Response.Write("<p>依Name降冪排序↓<br/>");
059        lstPerson.Sort(delegate(Person p1, Person p2) { return Comparer<string>.Default.Compare(p2.Name, p1.Name); });
060        foreach (Person p in lstPerson)
061        {
062            Response.Write(p.ToString() + "<br/>");
063        }
064    }
065}
066 
067public class Person
068{
069    private int _ID;
070    private string _Name;
071    private int _Age;
072 
073    public Person(int ID, string Name, int Age)
074    {
075        _ID = ID;
076        _Name = Name;
077        _Age = Age;
078    }
079 
080    public int ID
081    {
082        set { _ID = value; }
083        get { return _ID; }
084    }
085 
086    public string Name
087    {
088        set { _Name = value; }
089        get { return _Name; }
090    }
091 
092    public int Age
093    {
094        set { _Age = value; }
095        get { return _Age; }
096    }
097 
098    public override string ToString()
099    {
100        return string.Format("ID：{0}，Name：{1}，Age：{2}", _ID, _Name, _Age);
101    }
102}

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
posted @ 2009-12-22 11:52  高山-景行  阅读(1184)  评论(1)  编辑  收藏  举报