使用对象作为SortedList的键 <Object,Value> 在C＃中

Question

How would you define an Object as Key to a SortedList in c#.

Here I would like to definte a Key Object like this

   MyKey key = new MyKey();
   key.type = 3; // can be 3,2 or 1
   key.time = 2014-05-03 // DateTime in c# with timestamp
   key.sequence = 5567 // a number unique to the combination above

I would like to sort this sorted list on priority type, time and sequence. How do i achieve this?

Answer 1

Create a custom Comparer<myKey> and pass that to the SortedList constructor :

public class TypeComparer : Comparer<MyKey>
{
    public override int Compare(MyKey x, MyKey y)
    {
        if (ReferenceEquals(x, y)) return 0;
        int typeX = int.MinValue;
        int typeY = int.MinValue;
        if (x != null) typeX = x.type;
        if (y != null) typeY = y.type;
        return typeX.CompareTo(typeY);
    }
}

Now you can use this constructor:

var sl = new SortedList<MyKey, string>(new TypeComparer());

Answer 2

The SortedList in C# uses the IComparable interface for sorting the list. So for you to achieve this u must implement the IComparable interface. See: https://msdn.microsoft.com/en-us/library/system.icomparable.compareto(v=vs.110).aspx

A example:

public class Key : IComparable
{
    public int Type {get; set; }
    public DateTime Time { get; set; }
    public int Sequence { get; set; }

    int IComparable.CompareTo(object obj)
    {
        Key otherKey = obj as Key;
        if (otherKey == null) throw new ArgumentException("Object is not a Key!");

        if (Type > otherKey.Type)
            return 1;

       return -1;
    }
}

Use the sorted list:

SortedList<Key,string> collection = new SortedList<Key, string>();

collection.Add(new Key { Type = 2 }, "alpha");
collection.Add(new Key { Type = 1 }, "beta");
collection.Add(new Key { Type = 3 }, "delta");

foreach (string str in collection.Values)
{
    Console.WriteLine(str);
}

This writes:

beta

alpha

delta

Answer 3

If I understand correctly:

static void Main(string[] args)
{
    Dictionary<MyKey, string> fooDictionary = new Dictionary<MyKey, string>();
    fooDictionary.Add(new MyKey() {FooNumber=1, Sequence=50 }, "1");
    fooDictionary.Add(new MyKey() { FooNumber = 2, Sequence = 40 }, "2");
    fooDictionary.Add(new MyKey() { FooNumber = 3, Sequence = 30 }, "3");
    fooDictionary.Add(new MyKey() { FooNumber = 4, Sequence = 20 }, "4");
    fooDictionary.Add(new MyKey() { FooNumber = 5, Sequence = 10 }, "5");
    var result = from c in fooDictionary orderby c.Key.Sequence select c;
    Console.WriteLine("");   
}

class MyKey
{
    public int FooNumber { get; set; }
    public DateTime MyProperty { get; set; }
    public int Sequence { get; set; }
}