Illegal Forward Reference and Enums

Question

I\'m programming a game in java which is made up of a grid of tiles. I wan\'t to be able to inuitively define the edges of the tiles and how they relate to each other, e.g.

Answer 1

Here's another way

public enum Edge {

    TOP("BOTTOM"),
    BOTTOM("TOP"),
    LEFT("RIGHT"),
    RIGHT("LEFT");

    private String opposite;

    private Edge(String opposite){
        this.opposite = opposite;
    }

    public Edge opposite(){
        return valueOf(opposite);
    }

}

Peter Lawrey's solution is however more efficient and compiletime safe.