C# List去重
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();
}
}
}