获取重复对象的列表，包括所有出现的C＃

Question

I have a class MyClass

public class MyClass
{
    public int ID { set; get; }
    public string ITEM1 { set; get; }
    public string ITEM2 { set; get; }
}

And a list

List<MyClass> listMyClass = new List<MyClass>();

with 3 objects

  {1, "APPLE", "LIME"}
  {1, "LIME", "APPLE"}
  {2, "ORANGE", "LEMON"}

I would like to exclude non-duplicated objects BUT if there are 2 duplicated object, I want to list them all. So the result list I would like to have

  {1, "APPLE", "LIME"}
  {1, "LIME", "APPLE"}

I try

  var dupes = .GroupBy(g => g.ID).SelectMany(grp => grp.Skip(1)).ToList();

This only gives me

  {1, "APPLE", "LIME"}

Pleas ignore the reason why I have objects with same ID but have different contents. How could I get a full list of duplicated objects?

Answer 1

var dupes = listMyClass.GroupBy(i => i.ID).Where(i => i.Count() > 1).SelectMany(i => i).ToList();

Answer 2

这个怎么样？

var dupes = listMyClass.GroupBy(g => g.ID).SelectMany(grp => grp.Count() <= 1 ? new MyClass[] { } : grp.ToArray()).ToList();