自定义在lambda中相交

Question

我想知道使用lambda表达式是否可以解决这个问题:

List<Foo> listOne = service.GetListOne();
List<Foo> listTwo = service.GetListTwo();
List<Foo> result = new List<Foo>();

foreach(var one in listOne)
{
    foreach(var two in listTwo)
    {
        if((one.Id == two.Id) && one.someKey != two.someKey)
           result.Add(one);
    }
}

Answer 1

你当然可以!您可以使用Linq的扩展方法的这个重载,Intersect它采用IEqualityComparer<T>如下:

public class FooComparer : IEqualityComparer<Foo> 
{
    public bool Equals(Foo x, Foo y)
    {
        return x.Id == y.Id && x.someKey != y.someKey;
    }

    public int GetHashCode(Foo x)
    {
        return x.Id.GetHashCode();
    }
}

...

var comparer = new FooComparer();
List<Foo> listOne = service.GetListOne();
List<Foo> listTwo = service.GetListTwo();
List<Foo> result = listOne.Intersect(listTwo, comparer).ToList();

Answer 2

listOne.SelectMany(x=>listTwo.Where(y=>x.Id==y.Id && x.someKey != y.someKey));