I made an interface to work with JGraphT. My intended use is like Comparable
, in that implementing Comparable
allows objects to be used with certain data structures. Simiarly, I have a JGraphT function that I want to work with anything that is Distanceable
.
public interface Distanceable<E> {
/**
* A representation of the distance between these two objects.
* If the distance between a0 and a1 is undefined, <code>a0.hasEdge(a1)</code> should return false;
* @param o
* @return
*/
public int distance(E o);
/**
* Are these two objects connected?
* @param o
* @return True if the two objects are connected in some way, false if their distance is undefined
*/
public boolean hasEdge(E o);
}
Here is my JGraphT function in JGraphtUtilities. It's not defined for Animal
, but for Distanceable
:
public static <E extends Distanceable> WeightedGraph<E, DefaultWeightedEdge> graphOfDistances(Set<E> nodes) {
WeightedGraph<E, DefaultWeightedEdge> g = new SimpleWeightedGraph<E, DefaultWeightedEdge>(DefaultWeightedEdge.class);
for (E a : nodes) {
g.addVertex(a);
}
for (E a : nodes) {
for (E a1 : nodes) {
if (a.hasEdge(a1)) {
g.addEdge(a, a1);
g.setEdgeWeight(g.getEdge(a, a1), a.distance(a1));
}
}
}
return g;
}
But it doesn't work. The compiler produces an error on this line in another class that calls this method:
WeightedGraph<Animal, DefaultWeightedEdge> graphOfAnimals = JGraphtUtilities.graphOfAnimals(zoo);
The error is:
The method graphOfAnimals(Set<Animal>) is undefined for the type JGraphtUtilities
However,
public class Animal implements Distanceable<Animal> {
What am I doing wrong here?
Another issue: The compiler gives this warning:
Distanceable is a raw type. References to generic type Distanceable<E> should be parameterized.
What type do I want to give it, if I want this function to work with all Distanceable
objects?