Re: [jgrapht-users] Weighted graphs

[John V. S. <js...@gm...>]

The default edge implementations are optimized to be "intrusive"; that 
is, they contain direct references to their vertices.

When the graph sees an edge class that extends a default edge, it 
assumes that it can use these references rather than maintaining the 
edge/vertex association indirectly via a HashMap (which is more expensive).

In your case, you are creating a new edge on the fly, so when the graph 
examines it, the references are null.  When you use a non-default 
implementation everything works because then the new GRFEdge probably 
Object.equals some existing edge in the graph.

JVS

Fabian K wrote:
> my graph class:
> public class GRFGraph extends DefaultDirectedWeightedGraph<GRFNode, GRFEdge>
> 
> my Edge class:
> public class GRFEdge extends DefaultWeightedEdge
> 
> following method doesn't work anymore, it returns null.
> GRFNode srcNode = graph.getEdgeTarget(new GRFEdge(1));
> 
> when my GRFEdge doesnt extend DefaultWeightedEdge it works fine. It will
> return the node.
> 
> What is wrong with this call?
> 
> FYI:
> in my GRFEdge class I override getWeight method already.
> 
> @Override
> public double getWeight() {
>         return weight;
> }