Java Enum definition

Question

I thought I understood Java generics pretty well, but then I came across the following in java.lang.Enum:

class Enum>
         


        

Answer 1

This post has totally clarified to me these problem of 'recursive generic types'. I just wanted to add another case where this particular structure is necessary.

Suppose you have generic nodes in a generic graph:

public abstract class Node>
{
    public void addNeighbor(T);

    public void addNeighbors(Collection nodes);

    public Collection getNeighbor();
}

Then you can have graphs of specialized types:

public class City extends Node
{
    public void addNeighbor(City){...}

    public void addNeighbors(Collection nodes){...}

    public Collection getNeighbor(){...}
}