Question

2个班级

   public class Student
    {
        public int StudentID { get; set;}
        public string Name { get; set;}
        public List<Fee> Fees {get;set;}
    }

    public class Fee
    {
        public int FeeID { get; set;}
        public decimal FeeAmount { get; set; }
    }

假设有10个学生对象学生[] stud = new Student [10]

如果stud [0]有2笔费用（费用[2]）且

FeeID=1, FeeAmount=54.23
FeeID=2, FeeAmount=234.98

如果专栏[1]有1个费用（费用[2]），他们是

FeeID=1, FeeAmount=9.99

如果专栏[2]有3笔费用（费用[3]），他们是

FeeID=1, FeeAmount=123.45
FeeID=2, FeeAmount=67.89
FeeID=3, FeeAmount=987.65

我需要通过TotalAmount（费用收取）对学生收藏进行排序

TotalAmount of Fee 
stud[0] = 54.23+234.98=289.21
stud[1] = =9,99
stud[2] = 123.45+67.89+987.65=1178.99

在排序后应该变成

stud[0] = 123.45+67.89+987.65=1178.99
stud[1] = 54.23+234.98=289.21
stud[2] = =9,99

Answer 1

听起来你只是想要：

stud = stud.OrderByDescending(x => x.Fees.Sum(fee => fee.FeeAmount)).ToArray();

得爱LINQ：）

有几点需要注意：

这仍然只计算每位学生一次的费用总和
这将 not 当前处理null元素。你需要吗？（你似乎有一个固定的数组大小...也许使用List<Student>代替？）
除非你事后需要它作为一个数组，否则只需删除ToArray电话。请注意，除非您使用ToArray或ToList，否则每次迭代它都会对其进行排序。

Answer 2

var results = stud.OrderByDescending(s => s.Fees.Sum(f => f.FeeAmount)).ToArray();

Answer 3

一个简单的Linq查询应该完成这项工作：

stud =
    (from s in stud
     orderby s.Fees.Sum(f => f.FeeAmount)
     select s)
    .ToArray();

Answer 4

var students = new List<Student>() { .. add students here ... };
students.OrderBy(x => x.Fees.Sum(y => y.FeeAmount));

Answer 5

如果您使用旧的.net框架（没有Linq）：

public class Student : IComparable
{
    public int StudentID { get; set; }
    public string Name { get; set; }
    public List<Fee> Fees { get; set; }

    private decimal TotalAmount
    {
        get
        {
            decimal total = 0;
            if (Fees != null)
                foreach (var fee in Fees)
                    total += fee.FeeAmount;
            return total;
        }
    }

    public int CompareTo(object obj)
    {
        //Ascending
        //return TotalAmount.CompareTo((obj as Student).TotalAmount);

        //Descending
        return (obj as Student).TotalAmount.CompareTo(TotalAmount);
    }
}

public class Fee
{
    public int FeeID { get; set; }
    public decimal FeeAmount { get; set; }
}


List<Student> students = new List<Student>();
...
students.Sort();

Linq更好......

在另一个集合的总和内和之前对集合进行排序

5 个答案: