C＃中的参数枚举

Question

I'm used to programming in Java however for this project I'm supposed to be using C#, I'm trying to convert my Packet system over from my Java project, however I'm running into some issues using the C# Compiler. Here's the code.

abstract class Packet
{
    public static enum PacketTypes
    {
        INVALID(-1), LOGIN(00);

        private int packetId;

        private PacketTypes(int packetId)
        {
            this.packetId = packetId;
        }

        public int getId()  { return packetId; }

    }
}

This is actually exactly how it's done in my Java Code, and I have the individual packets extend the Packet class. I'm trying to figure out how to make this all come together in C#. Perhaps having a separate class for each packet isn't the way it should be done here?

Answer 1

I'm not sure what you're trying to achieve, but you can set values for particular enum elements in C#:

public enum PacketTypes
{
    INVALID = -1;
    LOGIN = 0;
}

Because enum is by default backed by int , you can cast it from/to int without additional code.

enum s in C# cannot content any members, so you can't add methods/properties/fields to enum declaration.

Answer 2

Unlike Java where enum s are classes, in C# enum s are plain values. They cannot have member functions or fields.

One approach that could help is to define an extension method for your enum , like this:

public static class PacketTypesExtensions {
    static readonly IDictionary<PacketTypes,int> IdForType = new Dictionary<PacketTypes,int> {
        { PacketTypes.INVALID, -1 }
    ,   { PacketTypes.LOGIN,    0 }
    };
    static readonly IDictionary<PacketTypes,string> DescrForType = new Dictionary<PacketTypes,string> {
        { PacketTypes.INVALID, "<invalid packet type>" }
    ,   { PacketTypes.LOGIN,   "<user login>" }
    };
    public static string Description(this PacketTypes t) {
        return DescrForType[t];
    }
    public static int Id(this PacketTypes t) {
        return IdForType[t];
    }
}

This lets you keep Java syntax:

PacketTypes pt = ... // <<== Assign a packet type here
int id = pt.Id();    // This calls the static extension method
string d = pt.Description();

Answer 3

You could try this in addition to Marcins answer.

public enum PacketTypes
{
    INVALID = -1;
    LOGIN = 0;
}

public class Packet
{
    public PacketTypes PacketType { get; set;}
}

In your code somewhere, you would do this

public void DoSomething()
{
    var packet = new Packet();
    packet.PacketType = PacketTypes.INVALID; // Assign packtype
    Console.WriteLine(packet.PacketType.ToString()); // Retrieve and print 
}