/**
* @param e The Edge to look up
* @return true iff this Graph contains the Edge e
*/
public boolean containsEdge(Edge e) {
if (e.getOne() == null || e.getTwo() == null) {
return false;
}
return this.edges.containsKey(e.hashCode());
}
/**
* 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;
}
/**
* This method adds an existing edge, which contains vertex one, two and weight.
*
* @param e
* @return true if no edge relating to one and two exists in the Graph
*/
public boolean addEdge(Edge e) {
if (e.getOne().equals(e.getTwo())) {
return false;
}
// ensures the Edge is not in the Graph
if (edges.containsKey(e.hashCode())) {
return false;
}
// and that the Edge isn't already incident to one of the vertices
else if (e.getOne().containsNeighbor(e) || e.getTwo().containsNeighbor(e)) {
return false;
}
edges.put(e.hashCode(), e);
e.getOne().addNeighbor(e);
e.getTwo().addNeighbor(e);
return true;
}
/**
* This method removes the specified Edge from the Graph, including as each vertex's incidence
* neighborhood.
*
* @param e The Edge to remove from the Graph
* @return Edge The Edge removed from the Graph
*/
public Edge removeEdge(Edge e) {
e.getOne().removeNeighbor(e);
e.getTwo().removeNeighbor(e);
return this.edges.remove(e.hashCode());
}