JUNG - Get position of vertex and save using Graphml

I'm trying to change a layout from CircleLayout to StaticLayout, keeping the positions of the Vertex, to do this im using the following code:

    StaticLayout<VertexType, EdgeType> sLayout = new StaticLayout<VertexType, EdgeType>(graph,
                new Transformer<VertexType, Point2D>() {
                    public Point2D transform(VertexType vertex) {
                        vertex.setX(layout.getX(vertex));
                        vertex.setY(layout.getY(vertex));
                        System.out.println(vertex.toString());
                        System.out.println(vertex.getX());
                        System.out.println(vertex.getY());
                        Point2D p = new Point2D.Double(vertex.getX(), vertex.getY());
                        return p;
                    }
                }, dimension);
        currentVV.setGraphLayout(sLayout);

Where currentVV is a VisualizationViewer and layout is a CircleLayout. setX(double) and setY(double) are methods from my custon Vertex, by default the vertex is initializated with x = 0.0 an y = 0.0. In this stage I used teh println to check if all vertex get their positions correctly and it is working. The next step is to save the graph using the GraphmlWritter:

    GraphMLWriter<VertexType, EdgeType> graphWriter = new GraphMLWriter<VertexType, EdgeType>();
        PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter(fileName)));
        graphWriter.addEdgeData("label", null, "0", new Transformer<EdgeType, String>() {
            @Override
            public String transform(EdgeType v) {
                return v.toString();
            }
        });
        graphWriter.addVertexData("x", null, "0", new Transformer<VertexType, String>() {
            public String transform(VertexType v) {
                return Double.toString(v.getX());
            }
        });
        graphWriter.addVertexData("y", null, "0", new Transformer<VertexType, String>() {
            public String transform(VertexType v) {
                return Double.toString(v.getY());
            }
        });
        graphWriter.save(graph, out);

The problems is that while most of the vertexes are being saved sucessfully, some of the vertexes are being saved with the default values to X and Y (0.0), and I have no idea why. If I try to save the graph from directly from the CircleLayout getting the X and Y values from the layout with:

    GraphMLWriter<VertexType, EdgeType> graphWriter = new GraphMLWriter<VertexType, EdgeType>();
        PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter(fileName)));
        graphWriter.addEdgeData("label", null, "0", new Transformer<EdgeType, String>() {
            @Override
            public String transform(EdgeType v) {
                return v.toString();
            }
        });
        graphWriter.addVertexData("x", null, "0", new Transformer<VertexType, String>() {
            public String transform(VertexType v) {
                return Double.toString(layout.getX(v));
            }
        });
        graphWriter.addVertexData("y", null, "0", new Transformer<VertexType, String>() {
            public String transform(VertexType v) {
                return Double.toString(layout.getY(v));
            }
        });

While this solution helps I would prefer to save the X and Y values on the vertex as it will be used for future implementations. Anyone knows where I'm missing the position info? Thanks.

I'm not immediately sure where the bug in your code is.

First question: why are you trying to convert a CircleLayout to a StaticLayout? What does that buy you?

Assuming that this is actually what you need to do, you don't need to serialize it at all; you can initialize any AbstractLayout subclass with the positions of any other Layout instance, because a Layout is (among other things a Function<V, Point2D>, which means you can pass it to an AbstractLayout instance as an "initializer". Thus, for example:

CircleLayout<V, E> circleLayout = ...
...
StaticLayout<V, E> staticLayout = new StaticLayout(graph, circleLayout);