[英]Sort Interface list C#
我正在嘗試按日期對接口列表進行排序,但我無法弄清楚。
var agencyList = new List<INewsItemBE>();
var item = new News1BE();
//add items
agencyList.Add(item)
var item = new News2BE();
//add items
agencyList.Add(item);
添加項目后,我想按日期用類似這樣的方式對agencyList
進行排序,但是我無法使其正常工作。
agencyList.Sort(delegate (News1BE c1, News1BE c2) { return c1.PublishDate.CompareTo(c2.PublishDate); });
agencyList.Sort(delegate (News1BE a, News1BE b) => a.PublishDate.CompareTo(b.PublishDate));
agencyList = agencyList.OrderBy(x => cant find anything at x.).ToList();
嘗試LINQ:
using System.Linq;
var ordered = agencyList.OrderBy(x => x.PublishDate);
或者,如果您需要降序排列:
var orderedDesc = agencyList.OrderByDescending(x => x.PublishDate);
如果您再次需要原始變量中的列表,則可以調用.ToList()
:
agencyList = agencyList.OrderBy(x => x.PublishDate).ToList();
如果LINQ不適用於您(或者您希望獲得最佳性能,從而減少LINQ帶來的開銷),則可以使用嘗試的.Sort
方法:
agencyList.Sort((item1, item2) => item1.PublishDate.CompareTo(item2.PublishDate));
您可以嘗試使用SortedList而不是List,這樣在添加項目時它將自動進行排序。
定義您的類/接口:
interface INews1BE
{
DateTime PublishedDate { get; set; }
}
class News1BE : INews1BE
{
public DateTime PublishedDate { get; set; }
}
為DateTime定義比較器:
class DateTimeAscendingComparer : IComparer<DateTime>
{
public int Compare(DateTime a, DateTime b)
{
return a.CompareTo(b);
}
}
現在創建比較器和將比較器傳遞給SortedList構造函數的排序列表:
var comparer = new DateTimeAscendingComparer();
var sortedList = new SortedList<DateTime, INews1BE>(comparer);
添加一些項目並檢查結果:
var item1 = new News1BE()
{
PublishedDate = DateTime.Now
};
var item2 = new News1BE()
{
PublishedDate = item1.PublishedDate.AddSeconds(-30)
};
sortedList.Add(item1.PublishedDate, item1);
//item2 goes before item1
sortedList.Add(item2.PublishedDate, item2);
foreach(var x in sortedList)
{
Console.WriteLine(x.Key);
}
您還可以通過值訪問對象:
foreach (var x in sortedList)
{
Console.WriteLine(x.Value.PublishedDate);
}
或者,您可以遍歷Values以立即訪問您的INews1BE對象:
foreach(var x in sortedList.Values)
{
Console.WriteLine(x.PublishedDate);
}
實際上,如果您只關心升序,則不必為DateTime定義比較器-這是默認行為,因此您可以創建SortedList而不將比較器傳遞給構造函數:
var sortedList = new SortedList<DateTime, INews1BE>();
但是,如果需要降序,只需在比較時將DateTime a
與DateTime b
切換即可:
class DateTimeDescendingComparer : IComparer<DateTime>
{
public int Compare(DateTime a, DateTime b)
{
return b.CompareTo(a);
}
}
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