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

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。

本文参考文章链接 ：http://www.codeproject.com/Articles/535374/DistinctBy-in-Linq-Find-Distinct-object-by-Propert