[jgrapht-users] Building a Graph with a Custom Vertex and Edge classes, and using the interface? & GraphImport

[docker d. <dev...@gm...>]

Hi,

I have been troubled by these issues over the last few days.

I am looking to build the graph outlined in the attached Graphml document.
Initially i tried to use GraphMLImporter, this came to no avail i was
continually receiving Parsing error my initial enquiry can be seen here:
https://stackoverflow.com/questions/61042189/jgrapht-failed-to-parse-graph

If anyone can show me how to import my graph that would solve my problem
immediately as i wouldn't have to go through the process of building and
trying to add my vertices and edges manually. I am at my wits end with this
some help on that would be really appreciated. I can send you any data or
the documents you need to help.

Failing that i have been trying to build the graph myself as i need to run
Dijkstra on the graph, i have created an ArrayList<Node> and
ArrayList<Edge> and i am trying to add them to a directed graph, I think i
may be missing the vertex interface at some point. Any help and pointers
would really help and you might save a man form pulling the rest of his
hair out.

public void createWayGraph(Context context) throws IOException {

    venueGraphTypeBuilder = GraphTypeBuilder
            .directed()
            .edgeClass(WayEdge.class)
            .vertexClass(WayNode.class)
            .weighted(true);
    venueGraph = venueGraphTypeBuilder.buildGraph();
   for(WayNode wn:wayNodeArrayList){
           venueGraph.addVertex(wn);
    }
    System.out.println("ddddddd "+venueGraph);
   for(WayEdge we:wayEdgeArrayList){
       venueGraph.addEdge(findSource(we), findDestination(we));
   }}

public WayNode findSource(WayEdge we){
    WayNode wn = null;
    for(WayNode w:wayNodeArrayList){
        String wayId = w.getId();
        String edgeSource = we.getSource();
        if(wayId==edgeSource){
            wn=w;
        }
    }
    return wn;
}

public WayNode findDestination(WayEdge we){
    WayNode wn = null;
    for(WayNode w:wayNodeArrayList){
        String wayId = w.getId();
        String edgeTarget = we.getTarget();
        if(wayId==edgeTarget){
            wn=w;
        }
    }
    return wn;
}


I get the error:

Caused by: java.lang.NullPointerException: throw with null exception
        at org.jgrapht.graph.AbstractGraph.assertVertexExist(AbstractGraph.java:129)
        at org.jgrapht.graph.AbstractBaseGraph.addEdge(AbstractBaseGraph.java:214)
        at com.app.WayGraph.WayGraph.createWayGraph(WayGraph.java:65)




I hope someone can help, Importing the graph would be the ideal option
as it will be the way i need to work.

Kindest regards,


Phil.