/**
* Accepts two vertices and a weight, and adds the edge ({one, two}, weight) iff no Edge relating
* one and two exists in the Graph.
*
* @param one The first Vertex of the Edge
* @param two The second Vertex of the Edge
* @param weight The weight of the Edge
* @return true iff no Edge already exists in the Graph
*/
public boolean addEdge(Vertex one, Vertex two, double weight) {
if (one.equals(two)) {
return false;
}
// ensures the Edge is not in the Graph
Edge e = new Edge(one, two, weight);
if (edges.containsKey(e.hashCode())) {
return false;
}
// and that the Edge isn't already incident to one of the vertices
else if (one.containsNeighbor(e) || two.containsNeighbor(e)) {
return false;
}
edges.put(e.hashCode(), e);
one.addNeighbor(e);
two.addNeighbor(e);
return true;
}
