What should the types of the edges be in this Graph ADT?

Question

I'm working on a game as a class project, and it was suggested to me to use a Graph ADT to represent the set of territories on a world map such that each vertex is a territory, and the edges represent adjacent territories that the player can move between. I found a good Java library for the Graph ADT (JGraphT) but I have absolutely no idea what type the edges should be...

For example, the Graph<V,E> interface clearly requires me to define an object type for the vertex (which I think makes perfect sense to use my Territory type) but what should the edges be? I can't think of any object type that makes sense to use as an edge.

Answer 1

Well, for example:

(1)

public class Border {
   // ... put here anything that's useful
   // e.g. length of border or type of border (land,sea,river)
}

The edge is actually the border between the two territories.

So for me it makes sense your edge to be of class Border.

Another idea:

(2)

public class Distance {
   // ... put here anything that's useful
   // e.g. the distance between the two capitals
}

I usually represent those graphs in my head as if the vertices are the capitals, and the edges are say the roads between the capitals (of any two bordering states/territories, I mean).