List<object>进行Distinct()去重

原文:List<object>进行Distinct()去重

有时我们会对一个list<T>集合里的数据进行去重，C#提供了一个Distinct()方法直接可以点得出来。如果list<T>中的T是个自定义对象时直接对集合Distinct是达不到去重的效果。我们需要新定义一个去重的类并继承IEqualityComparer接口重写Equals和GetHashCode方法，如下Demo

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4
 5 namespace MyTestCode
 6 {
 7     /// <summary>
 8     /// Description of DistinctDemo.
 9     /// </summary>
10     public class DistinctDemo
11     {
12         private static List<Student> list;
13         public DistinctDemo()
14         {
15         }
16
17         public static void init()
18         {
19             list = new List<Student>{
20                 new Student{
21                     Id=1,
22                     Name="xiaoming",
23                     Age=22
24                 },
25                 new Student{
26                     Id=2,
27                     Name="xiaohong",
28                     Age=23
29                 },
30                 new Student{
31                     Id=2,
32                     Name="xiaohong",
33                     Age=23
34                 },
35             };
36         }
37
38         public void Display()
39         {
40             list = list.Distinct(new ListDistinct()).ToList();
41             foreach (var element in list) {
42                 Console.WriteLine(element.Id +"/"+element.Name+"/"+element.Age);
43             }
44         }
45
46     }
47
48     public class Student
49     {
50         public int Id{get;set;}
51         public string Name{get;set;}
52         public int Age{get;set;}
53     }
54
55     public class ListDistinct : IEqualityComparer<Student>
56     {
57         public bool Equals(Student s1,Student s2)
58         {
59             return (s1.Name == s2.Name);
60         }
61
62         public int GetHashCode(Student s)
63         {
64             return s==null?0:s.ToString().GetHashCode();
65         }
66     }
67 }