三种去重的方法
1、List中的元素实现IEquatabe接口，并提供Equals方法和GetHashCode方法。
2、使用表达式
- users.Where((x,i)=>users.FindIndex(z=>z.name == x.name) == i)
去重，这条语句返回结果只保留users这个List中重复的元素的第一个(name相等认为重复)。
3、使用循环，判断每个元素是否重复
- using System;
- using System.Collections.Generic;
- using System.Linq;
- namespace NonDuplicateList
- {
- class Program
- {
- static void Main(string[] args)
- {
- List<User> users = new List<User>();
- users.Add(new User("张三", "永丰路299号"));
- users.Add(new User("张三", "上地西路8号"));//重复项，去重后将删掉
- users.Add(new User("李四", "海鹰路甲一号"));
- List<User> nonDuplicateList1 = users.Distinct().ToList();//通过User类的Equals实现去重
- List<User> nonDuplicateList2 = users.Where((x,i)=>users.FindIndex(z=>z.name == x.name) == i).ToList();//Lambda表达式去重
- List<User> nonDuplicateList3 = new List<User>();//通过循环方式去重
- foreach(User user in users)
- {
- if(nonDuplicateList3.Exists(x=>x.name==user.name) == false)
- {
- nonDuplicateList3.Add(user);
- }
- }
- foreach(List<User> list in new Object[]{nonDuplicateList1,nonDuplicateList2,nonDuplicateList3})//打印出三个List的元素
- {
- Console.Write("nonDuplicateList:\r\n");
- foreach(User u in list)
- {
- Console.WriteLine("\t" + u.ToString());
- }
- }
- Console.Read();
- }
- }
- class User:IEquatable<User>//继承IEquatable接口，实现Equals方法。List就可以使用Distinct去重
- {
- public string name { get; set; }
- string address;
- public User(string _name, string _address)
- {
- name = _name;
- address = _address;
- }
- public override string ToString()
- {
- return string.Format("name:{0},\taddress:{1}", name, address);
- }
- public bool Equals(User other)
- {
- return this.name == other.name;
- }
- public override int GetHashCode()
- {
- return name.GetHashCode();
- }
- }
- }