如何按对象中的属性对列表排序

我能想到的最简单的方法是使用Linq:

List<Order> SortedList = objListOrder.OrderBy(o=>o.OrderDate).ToList();

如果需要对列表进行排序,那么可以使用 Sort 方法,传递 Comparison<T>

objListOrder.Sort((x, y) => x.OrderDate.CompareTo(y.OrderDate));

OrderBy 方法,如其他答案所述。

List<Order> objListOrder = GetOrderList();
objListOrder.Sort(
    delegate(Order p1, Order p2)
    {
        return p1.OrderDate.CompareTo(p2.OrderDate);
    }
);

如果你在.Net3.0上,那么LukeH answer

要对多个属性进行排序,仍然可以在委托中进行排序。例如:

orderList.Sort(
    delegate(Order p1, Order p2)
    {
        int compareDate = p1.Date.CompareTo(p2.Date);
        if (compareDate == 0)
        {
            return p2.OrderID.CompareTo(p1.OrderID);
        }
        return compareDate;
    }
);

日期 降序

IComparer 把它传给你的朋友 Sort here

public class MyOrderingClass : IComparer<Order>
{
    public int Compare(Order x, Order y)
    {
        int compareDate = x.Date.CompareTo(y.Date);
        if (compareDate == 0)
        {
            return x.OrderID.CompareTo(y.OrderID);
        }
        return compareDate;
    }
}

IComparer<Order> comparer = new MyOrderingClass();
orderList.Sort(comparer);

排序列表的最简单方法是使用 OrderBy

 List<Order> objListOrder = 
    source.OrderBy(order => order.OrderDate).ToList();

如果您想按多个列排序,如下面的SQL查询。

ORDER BY OrderDate, OrderId

要实现这一点,您可以使用 ThenBy 喜欢跟在后面。

  List<Order> objListOrder = 
    source.OrderBy(order => order.OrderDate).ThenBy(order => order.OrderId).ToList();

没有Linq的情况下,就像你说的:

public class Order : IComparable
{
    public DateTime OrderDate { get; set; }
    public int OrderId { get; set; }

    public int CompareTo(object obj)
    {
        Order orderToCompare = obj as Order;
        if (orderToCompare.OrderDate < OrderDate || orderToCompare.OrderId < OrderId)
        {
            return 1;
        }
        if (orderToCompare.OrderDate > OrderDate || orderToCompare.OrderId > OrderId)
        {
            return -1;
        }

        // The orders are equivalent.
        return 0;
    }
}

然后只需在订单列表中调用.sort()

经典的面向对象解决方案

CompareTo 参数变为类型安全。

public class Order : IComparable<Order> {

    public int CompareTo( Order that ) {
        if ( that == null ) return 1;
        if ( this.OrderDate > that.OrderDate) return 1;
        if ( this.OrderDate < that.OrderDate) return -1;
        return 0;
    }
}

// in the client code
// assume myOrders is a populated List<Order>
myOrders.Sort(); 

这个默认的可排序性当然是可重用的。也就是说,每个客户机不必冗余地重新编写排序逻辑。交换“1”和“-1”(或逻辑运算符,由您选择)将反转排序顺序。

//用于gridview的完全通用排序

public List<T> Sort_List<T>(string sortDirection, string sortExpression, List<T> data)
    {

        List<T> data_sorted = new List<T>();

        if (sortDirection == "Ascending")
        {
            data_sorted = (from n in data
                              orderby GetDynamicSortProperty(n, sortExpression) ascending
                              select n).ToList();
        }
        else if (sortDirection == "Descending")
        {
            data_sorted = (from n in data
                              orderby GetDynamicSortProperty(n, sortExpression) descending
                              select n).ToList();

        }

        return data_sorted;

    }

    public object GetDynamicSortProperty(object item, string propName)
    {
        //Use reflection to get order type
        return item.GetType().GetProperty(propName).GetValue(item, null);
    }

下面是一个通用的LINQ扩展方法,它不会创建列表的额外副本:

public static void Sort<T,U>(this List<T> list, Func<T, U> expression)
    where U : IComparable<U>
{
    list.Sort((x, y) => expression.Invoke(x).CompareTo(expression.Invoke(y)));
}

要使用它:

myList.Sort(x=> x.myProperty);

我最近建立了这个额外的一个接受 ICompare<U> ,以便自定义比较。当我需要做一个自然的字符串排序时,这就派上了用场:

public static void Sort<T, U>(this List<T> list, Func<T, U> expression, IComparer<U> comparer)
    where U : IComparable<U>
{    
    list.Sort((x, y) => comparer.Compare(expression.Invoke(x), expression.Invoke(y)));
}

objListOrder = GetOrderList()
                   .OrderBy(o => o.OrderDate)
                   .ToList();

objListOrder = GetOrderList()
                   .OrderBy(o => o.OrderId)
                   .ToList();

//Get data from database, then sort list by staff name:

List<StaffMember> staffList = staffHandler.GetStaffMembers();

var sortedList = from staffmember in staffList
                 orderby staffmember.Name ascending
                 select staffmember;

请让我通过@LukeH和一些示例代码来完成答案,因为我已经测试了它,我相信它可能对某些人有用:

public class Order
{
    public string OrderId { get; set; }
    public DateTime OrderDate { get; set; }
    public int Quantity { get; set; }
    public int Total { get; set; }

    public Order(string orderId, DateTime orderDate, int quantity, int total)
    {
        OrderId = orderId;
        OrderDate = orderDate;
        Quantity = quantity;
        Total = total;
    }
}

public void SampleDataAndTest()
{
    List<Order> objListOrder = new List<Order>();

    objListOrder.Add(new Order("tu me paulo ", Convert.ToDateTime("01/06/2016"), 1, 44));
    objListOrder.Add(new Order("ante laudabas", Convert.ToDateTime("02/05/2016"), 2, 55));
    objListOrder.Add(new Order("ad ordinem ", Convert.ToDateTime("03/04/2016"), 5, 66));
    objListOrder.Add(new Order("collocationem ", Convert.ToDateTime("04/03/2016"), 9, 77));
    objListOrder.Add(new Order("que rerum ac ", Convert.ToDateTime("05/02/2016"), 10, 65));
    objListOrder.Add(new Order("locorum ; cuius", Convert.ToDateTime("06/01/2016"), 1, 343));


    Console.WriteLine("Sort the list by date ascending:");
    objListOrder.Sort((x, y) => x.OrderDate.CompareTo(y.OrderDate));

    foreach (Order o in objListOrder)
        Console.WriteLine("OrderId = " + o.OrderId + " OrderDate = " + o.OrderDate.ToString() + " Quantity = " + o.Quantity + " Total = " + o.Total);

    Console.WriteLine("Sort the list by date descending:");
    objListOrder.Sort((x, y) => y.OrderDate.CompareTo(x.OrderDate));
    foreach (Order o in objListOrder)
        Console.WriteLine("OrderId = " + o.OrderId + " OrderDate = " + o.OrderDate.ToString() + " Quantity = " + o.Quantity + " Total = " + o.Total);

    Console.WriteLine("Sort the list by OrderId ascending:");
    objListOrder.Sort((x, y) => x.OrderId.CompareTo(y.OrderId));
    foreach (Order o in objListOrder)
        Console.WriteLine("OrderId = " + o.OrderId + " OrderDate = " + o.OrderDate.ToString() + " Quantity = " + o.Quantity + " Total = " + o.Total);

    //etc ...
}

罗杰版本的改进版。

例子:

“Employee.Company.Name;”会崩溃。。。因为只允许“Name”作为参数来获取其值。

这是一个改进的版本,允许我们按导航属性排序。

public object GetDynamicSortProperty(object item, string propName)
    {
        try
        {                 
            string[] prop = propName.Split('.'); 

            //Use reflection to get order type                   
            int i = 0;                    
            while (i < prop.Count())
            {
                item = item.GetType().GetProperty(prop[i]).GetValue(item, null);
                i++;
            }                     

            return item;
        }
        catch (Exception ex)
        {
            throw ex;
        }


    } 

将函数编写为泛型函数:

public List<Order> GetOrderList<T>(IEnumerable<Order> orders, Func<Order, T> propertySelector)
        {
            return (from order in orders
                    orderby propertySelector(order)
                    select order).ToList();
        } 

然后像这样使用:

var ordersOrderedByDate = GetOrderList(orders, x => x.OrderDate);

public List<T> OrderBy<T,P>(IEnumerable<T> collection, Func<T,P> propertySelector)
        {
            return (from item in collection
                    orderby propertySelector(item)
                    select item).ToList();
        } 

var ordersOrderedByDate = OrderBy(orders, x => x.OrderDate);

这是一种愚蠢的、不必要的、复杂的方式来执行LINQ样式的“OrderBy”, 但它可能会给你一个线索,告诉你如何以一种通用的方式实现它

var obj = db.Items.Where...

var orderBYItemId = obj.OrderByDescending(c => Convert.ToInt32(c.ID));

利用LiNQ OrderBy

List<Order> objListOrder=new List<Order> ();
    objListOrder=GetOrderList().OrderBy(o=>o.orderid).ToList();

基于 的比较器:
我们可以通过添加排序标志来获得更大的灵活性:

public class MyOrderingClass : IComparer<Order> {  
    public int Compare(Order x, Order y) {  
        int compareDate = x.Date.CompareTo(y.Date);  
        if (compareDate == 0) {  
            int compareOrderId = x.OrderID.CompareTo(y.OrderID);  

            if (OrderIdDescending) {  
                compareOrderId = -compareOrderId;  
            }  
            return compareOrderId;  
        }  

        if (DateDescending) {  
            compareDate = -compareDate;  
        }  
        return compareDate;  
    }  

    public bool DateDescending { get; set; }  
    public bool OrderIdDescending { get; set; }  
}  

MyOrderingClass类 明确地(而不是 )
要设置其排序属性:

MyOrderingClass comparer = new MyOrderingClass();  
comparer.DateDescending = ...;  
comparer.OrderIdDescending = ...;  
orderList.Sort(comparer);  

以上答案对我来说都不够笼统,所以我做了这个:

var someUserInputStringValue = "propertyNameOfObject i.e. 'Quantity' or 'Date'";
var SortedData = DataToBeSorted
                   .OrderBy(m => m.GetType()
                                  .GetProperties()
                                  .First(n => 
                                      n.Name == someUserInputStringValue)
                   .GetValue(m, null))
                 .ToList();

不过,在海量数据集上要小心。这是一个简单的代码,但如果集合很大,并且集合的对象类型有大量字段,则可能会给您带来麻烦。 运行时间为NxM,其中:

N=集合中元素的#

M=对象中属性的#

任何使用可空类型的人, Value CompareTo .

objListOrder.Sort((x, y) => x.YourNullableType.Value.CompareTo(y.YourNullableType.Value));

public class Passenger
{
    public string Name { get; }
    public string LastName { get; }
    public string PassportNo { get; }
    public string Nationality { get; }

    public Passenger(string name, string lastName, string passportNo, string nationality)
    {
        this.Name = name;
        this.LastName = lastName;
        this.PassportNo = passportNo;
        this.Nationality = nationality;
    }

    public static int CompareByName(Passenger passenger1, Passenger passenger2)
    {
        return String.Compare(passenger1.Name, passenger2.Name);
    }

    public static int CompareByLastName(Passenger passenger1, Passenger passenger2)
    {
        return String.Compare(passenger1.LastName, passenger2.LastName);
    }

    public static int CompareNationality(Passenger passenger1, Passenger passenger2)
    {
        return String.Compare(passenger1.Nationality, passenger2.Nationality);
    }
}

public class TestPassengerSort
{
    Passenger p1 = new Passenger("Johon", "Floid", "A123456789", "USA");
    Passenger p2 = new Passenger("Jo", "Sina", "A987463215", "UAE");
    Passenger p3 = new Passenger("Ped", "Zoola", "A987855215", "Italy");

    public void SortThem()
    {
        Passenger[] passengers = new Passenger[] { p1, p2, p3 };
        List<Passenger> passengerList = new List<Passenger> { p1, p2, p3 };

        Array.Sort(passengers, Passenger.CompareByName);
        Array.Sort(passengers, Passenger.CompareByLastName);
        Array.Sort(passengers, Passenger.CompareNationality);

        passengerList.Sort(Passenger.CompareByName);
        passengerList.Sort(Passenger.CompareByLastName);
        passengerList.Sort(Passenger.CompareNationality);

    }
}

因此,您可以通过使用组合委托来实现排序结构。

从性能的角度来看,最好的方法是使用排序列表,以便在将数据添加到结果时对其进行排序。 查看System.Collections.Generic命名空间,然后选择一个具有排序而不是列表的类。

尽可能避免使用反射的泛型实现,这也会导致性能问题。

如果您想排序这个序列的列表“1”“10”“100”“200”“2”“20”“3”“30”“300”,并得到这个表单中的排序项1;2;三;10;20;30;100;200;300您可以使用:

 public class OrderingAscending : IComparer<String>
    {
        public int Compare(String x, String y)
        {
            Int32.TryParse(x, out var xtmp);
            Int32.TryParse(y, out var ytmp);

            int comparedItem = xtmp.CompareTo(ytmp);
            return comparedItem;
        }
    }

您可以在以下表单的代码隐藏中使用它:

 IComparer<String> comparerHandle = new OrderingAscending();
 yourList.Sort(comparerHandle);

• 在解析Id之后,使用Sort函数和委托对Id进行排序 价值

    class Question
    {
        public List<QuestionInfo> Questions Info{ get; set; }
    
    }

    class QuestionInfo
    {
        public string Id{ get; set; }
        public string Questions{ get; set; }
    
    }

    var questionnaire = new Question();

    questionnaire.QuestionInfo.Sort(delegate(Entities.Question x, Entities.Question y)
                        {
                            return int.Parse(x.Id) - int.Parse(y.Id);
                        });