https://zxbcw.cn/post/201932/
新建一个Person类
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public class Person
{
public Person(string name,int id)
{
Name = name;
Id = id;
}
public string Name { get; set; }
public int Id { get; set; }
}
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初始化List 中有一百万条数据，然后分别通过每种方法判断xiaoming是否在List中，代码如下
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static void Main(string[] args)
{
List<Person> persons = new List<Person>();
//初始化persons数据
for (int i = 0; i < 1000000; i++)
{
Person person = new Person("My" + i,i);
persons.Add(person);
}
Person xiaoming=new Person("My999999", 999999);
//下面通过三种方法判断persons中是否包含xiaoming
Stopwatch watch = new Stopwatch();
watch.Start();
bool a = persons.Contains(xiaoming);
watch.Stop();
Stopwatch watch1 = new Stopwatch();
watch1.Start();
bool b = persons.Exists(x=>x.Id==xiaoming.Id);
watch1.Stop();
Stopwatch watch2 = new Stopwatch();
watch2.Start();
bool c = persons.Where(x=>x.Id==xiaoming.Id).Any();
watch2.Stop();
Stopwatch watch3 = new Stopwatch();
watch3.Start();
bool d = persons.Any(x => x.Id == xiaoming.Id);
watch3.Stop();
Console.WriteLine("Contains耗时：" + watch.Elapsed.TotalMilliseconds);
Console.WriteLine("Exists耗时：" + watch1.Elapsed.TotalMilliseconds);
Console.WriteLine("Where耗时：" + watch2.Elapsed.TotalMilliseconds);
Console.WriteLine("Any耗时：" + watch3.Elapsed.TotalMilliseconds);
Console.ReadLine();
}
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执行结果如下图所示
结论
通过上图可以看出性能排序为
Contains > Exists > Where > Any
注意：
Contains中不能带查询条件