看看项可枚举存在一次（LINQ） [英] See if item exists once in Enumerable (Linq)

问题描述

给出一个列表...

class Item
{
 public Name
 {
   get;
   set;
 }
}

List<Item> items = new List<Item>
{
 new Item() { Name = "Item 1" },
 new Item() { Name = "Item 1" },
 new Item() { Name = "Item 2" },
 new Item() { Name = "Item 3" }
}

List<Item> listing = new List<Item>
{
 new Item() { Name = "Item 1" },
 new Item() { Name = "Item 2" },
 new Item() { Name = "Item 3" }
 new Item() { Name = "Item 4" }
}

等

我需要创建一个第三个数组，将抵消这两者之间的双实例;然而与名称1的项目都是一样的，但不同的实例。所以第三个列表应该有1项第1例中，由于'项目'有2个实例。这是如何通过LINQ的做任何想法？

I need to create a third array that will cancel out double instances between the two; however items with "Name 1" are both the same, but different 'instances'. So the third List should have 1 instance of Item 1, since 'items' had 2 instances. Any ideas of how this can be done through Linq?

推荐答案

首先，你需要创建一个 EqualityComparer 为项目。

First you need to create an EqualityComparer for Item.

public sealed class ItemEqualityComparer : EqualityComparer<Item>
{
    public override bool Equals(Item x, Item y)
    {
        return x.Name.CompareTo(y.Name) == 0;
    }

    public override int GetHashCode(Item obj)
    {
        return obj.Name.GetHashCode();
    }
}

然后你需要调用是<$ C $ 。C>联盟

var itemUnion = items.Union(listing, new ItemEqualityComparer());

这篇关于看看项可枚举存在一次（LINQ）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！