检索出 IList<T> 或 List<T>中的不重复数据 Distinct()

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http://www.soaspx.com/dotnet/csharp/csharp_20130513_10318.html

Distinct()方法在MSDN中的示例

public class Product{    public string Name { get; set; }    public int Code { get; set; }}

Product[] products = { new Product { Name = "apple", Code = 9 },                        new Product { Name = "orange", Code = 4 },                        new Product { Name = "apple", Code = 10 },                        new Product { Name = "lemon", Code = 9 } };var lstDistProduct = products.Distinct();foreach (Product p in list1){     Console.WriteLine(p.Code + " : " + p.Name);}

但在实际使用中发现往往无法实现筛选出不重复的数据的目的

查找相关资料获得如下方法：

方法1：使用MoreLinq库

var list1 = products.DistinctBy(x=> x.Code);foreach (Product p in list1){     Console.WriteLine(p.Code + " : " + p.Name);}

方法2：

class ProductComparare : IEqualityComparer<product>    {        private Func<Product, object> _funcDistinct;        public ProductComparare(Func<Product, object> funcDistinct)        {            this._funcDistinct = funcDistinct;        }        public bool Equals(Product x, Product y)        {            return _funcDistinct(x).Equals(_funcDistinct(y));        }        public int GetHashCode(Product obj)        {            return this._funcDistinct(obj).GetHashCode();        }    }

var list2 = products.Distinct(new ProductComparare( a => a.Code ));            foreach (Product p in list2)            {                Console.WriteLine(p.Code + " : " + p.Name);            }

方法3：

 List<Product> list = products                   .GroupBy(a => a.Code )                   .Select(g => g.First())                   .ToList();            foreach (Product p in list)            {                Console.WriteLine(p.Code + " : " + p.Name);            }

本人通过第三种方法得到了想要的不重复数据。

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