Repast: set different color for different edges

Question

I have two types edges in my supply chain model: demand_links and supply_links. the default color is gray for all links. But I want to change the color of demand_links to red each time the attribute of the demand_link is changed (Note:the edge is the custom edge agent through edge creator). How to do this?

Below is my codes for simple test and it didn't work.

    public class EdgeStyle2D extends DefaultStyleOGL2D {

    @Override
    public Color getColor(Object o){

//      if (((CustomEdge) o).getCurrent_dl() == 1) {
//          return Color.RED;       
//      }
//      else {
//          return Color.BLACK;
//      }


        if (o instanceof Distributor) 
            return Color.YELLOW;


        return null;
    }

}

I get the error when initialize.

Caused by: java.lang.ClassCastException: class supplyChainSystem.EdgeStyle2D cannot be cast to class repast.simphony.visualizationOGL2D.EdgeStyleOGL2D (supplyChainSystem.EdgeStyle2D and repast.simphony.visualizationOGL2D.EdgeStyleOGL2D are in unnamed module of loader repast.simphony.plugin.ExtendablePluginClassLoader @61af1510)

Answer 1

For styling links in this way, you should follow the example in the zombies.style.LinkStyle class within the Zombies_Demo model. Here's what the relevant parts of that class look like:

public class LinkStyle implements EdgeStyleOGL2D {

    public Color getColor(RepastEdge<?> edge) {
        BaseLink<?> link = (BaseLink<?>) edge;
        return ReLogoSupport.lookupColor(link.getColor());
    }

    public int getLineWidth(RepastEdge<?> edge) {
        return (int) (Math.abs(edge.getWeight()));
    }

}

And you would use a class like this for the network (as opposed to agent) style.