从C＃List 获取重复项

我有以下List定义：

class ListItem { public int accountNumber { get; set; } public Guid locationGuid { get; set; } public DateTime createdon { get; set; } } class Program { static void Main(string[] args) { List entitiesList = new List(); // Some code to fill the entitiesList } } 

entitiesList的accountNumbers中有重复项。 我想找到重复的accountNumbers，在locationGuids上执行一个操作，其创建日期不是重复项的最新创建日期。 如何操作列表以仅获取重复项accountNumber，最近创建的locationGuid和（较旧的）locationGuids？

Answer 1

 List entitiesList = new List(); //some code to fill the list var duplicates = entitiesList.OrderByDescending(e => e.createdon) .GroupBy(e => e.accountNumber) .Where(e => e.Count() > 1) .Select(g => new { MostRecent = g.FirstOrDefault(), Others = g.Skip(1).ToList() }); foreach (var item in duplicates) { ListItem mostRecent = item.MostRecent; List others = item.Others; //do stuff with others } 

Answer 2

 duplicates = entitiesList.GroupBy(e => e.accountNumber) .Where(g => g.Count() > 1) .Select(g => g.OrderByDescending(x => x.createdon)); 

Answer 3

  List entitiesList = new List(); var filtered = entitiesList.GroupBy(x => x.accountNumber).Where(g => g.Count() > 1).ToList().OrderByDescending(x => x.createdon);