尝试按枚举属性对对象列表进行排序

Question

I have a data structure like the following:

public enum Direction
{
  NONE, // SHOULD NEVER BE THIS
  UP,
  DOWN,
  LEFT,
  RIGHT
};

public struct dataStruct
{
   public Direction direction;

  public int CompareTo(dataStruct other)
  {
    return this.direction.CompareTo(other.direction);
  }
}

I'll have a list of dataStruct, and I want to be able to sort it according to the Direction. So all the dataStruct with UP comes first, followed by DOWN, LEFT and finally RIGHT.

I tried to sort it with the following code,

ListOfData.Sort(
  delegate(dataStruct obj1, dataStruct obj2)
  {
    return obj1.direction.CompareTo(obj2.direction);
  }
);

But this gives me an error. Am I doing something wrong?

Edit: I get the following error ArgumentException: does not implement right interface System.Collections.Generic.Comparer`1+DefaultComparer[dataStruct].Compare (dataStruct x, dataStruct y)

Answer 1

Add IComparable<dataStruct> to struct declaration.

public struct dataStruct : IComparable<dataStruct>

And just execute

ListOfData.Sort()

Answer 2

Try this:

var x = ListOfData.OrderByDescending
              (ListOfData => (Direction)Enum.Parse(typeof(Direction), ListOfData.Direction, true));

or simply

var x = ListOfData.OrderByDescending(i=> i.Direction);

Answer 3

If you just need to sort it by the direction, this simple code works. Why do you need a CompareTo ?:

public class Program
{
    public void Main(string[] args)
    {
        List<dataStruct> objs = new List<dataStruct>(){
            new dataStruct{direction = Direction.DOWN, id=1},
            new dataStruct{direction = Direction.LEFT, id =2},
            new dataStruct{direction = Direction.UP, id =3},
        };

        var result = objs.OrderBy(x=>x.direction);

        foreach (var element in result)
        {
            Console.WriteLine ("{0}, {1}", element.direction, element.id);
        }
    }
}

public struct dataStruct
{
    public Direction direction;
    public int id;
    //other properties
}

public enum Direction
{
  NONE, // SHOULD NEVER BE THIS
  UP,
  DOWN,
  LEFT,
  RIGHT
};

Answer 4

You should create

public class DirectionComparer:IComparer<TypeOfData>
{
  public int Compare(dataStruct other)
  {
    return this.direction.CompareTo(other.direction);
  }
}

where TypeOfData is type of elements in ListOfData

and pass instatnce of it to sort method.

ListOfData.Sort(new DirectionComparer());