Question

I need some help with Serialization of draw2d Layered Panes. I read about Serialization, and found that a Class can be serialized only if it implements Serializable Interface, and all its fields are either themselves Serializable, or transient.

I have a very Complex Diagram that I need to serialize, and don’t have a clue as to how to proceed? I found out that the LayeredPane class only contains one field of type List. In any case, can any one help with how one can write, say a recursive method or something, to make a LayeredPane Object Serializable?

@mKorbel
A Sample scenario of the Problem I am facing is difficult to give, as its part of a really large application. Still, I’ve made up a case, which may give you an idea of the Problem:

public class Editor extends org.eclipse.ui.part.EditorPart {
    org.eclipse.draw2d.FreeformLayer objectsLayer;
    org.eclipse.draw2d.ConnectionLayer connectionLayer;
    public void createPartControl(Composite parent) {
        org.eclipse.draw2d.FigureCanvas canvas = new org.eclipse.draw2d.FigureCanvas(composite);

        org.eclipse.draw2d.LayeredPane pane = new org.eclipse.draw2d.LayeredPane();

        objectsLayer = new org.eclipse.draw2d.FreeformLayer();
        connectionLayer = org.eclipse.draw2d.ConnectionLayer();

        pane.add(objectsLayer);
        pane.add(connectionLayer);

        canvas.setContents(pane);

        addFigures();
        addConnections();
    }

    private void addFigures() {
        // Adds Objects, i.e.,  org.eclipse.draw2d.Figure Objects, to the objectLayer
        // which turn contains, 1 or more org.eclipse.draw2d.Panel Objects, 
        // with variable number of org.eclipse.draw2d.Label objects
    }

    private void addConnections() {
        // Adds org.eclipse.draw2d.PolylineConnection objects to the connectionLayer
        // between objects in the objectLayer
    }
}

Answer 1

You have to extend the LayeredPane class, make it Serializable by implementing that interface and provide a method that rebuild the whole structure and properties of that LayeredPane from a model.

public class SerializableLayeredPanne extends LayeredPanne implements Serializable {

    private static final long serialVersionUID = 1L;

    /** 
     * the model you are able to FULLY restore layered pane and all its children from,
     * it MUST be serializable 
     */
    private final Serializable model;

    SerializableLayeredPanne(Serializable model) {
        this.model  = model;
    }

    public void init() {
        // set font, color etc.
        // add children
    }

    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
        in.defaultReadObject();
        init();
    }

}

So you have to add a Serializable model that contains all informations you need to build the figure tree from scratch.