List去重方法

DiffKnow / 2023-05-06 / 原文

方法一：遍历list

循环遍历List，借助Dictionary存储去重的对象

Dictionary<string, Item> result = new Dictionary<string, Item>();
foreach (Item item in list)//list为待去重列表
{
    Item temp;
    if (!result.TryGetValue(item.name, out temp))
    {
        result.Add(item.name, item);
    }
}
List<Item> result_list = result.Values.ToList();



///Item
public class Item
{
    public string name { get; set; }
    public string value { get; set; }
}

方法二：ToLookup

利用ToLookup查找，并转为Dictionary

List<Item> result = list.ToLookup(item => item.name).ToDictionary(item => item.Key, item => item.First()).Values.ToList();


///Item
public class Item
{
    public string name { get; set; }
    public string value { get; set; }
}

方法三：自定义Compare

自定义Compare方法实现

List<Item> result = list.Distinct(new Compare()).ToList();



//compare方法
public class Compare : IEqualityComparer<Item>
{
    public bool Equals(Item a, Item b)
    {
        return a.name == b.name;
    }

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

///Item
public class Item
{
    public string name { get; set; }
    public string value { get; set; }
}

方法四：groupby

利用GroupBy分组实现

List<Item> result = list.GroupBy(item => item.name).Select(item => item.First()).ToList();

///Item
public class Item
{
    public string name { get; set; }
    public string value { get; set; }
}