Question

I have a class to store a list of SWT widgets.

@XmlRootElement
class Test {
    private List<Widget> widgets;

    public List<Widget> getWidgets() {
        return widgets;
    }

    public void setWidgets(List<Widget> widgets) {
        this.widgets = widgets;
    }
}

I used JAXB to marshall it into XML. However, these widgets are not marshalled.

Test t = new Test();
t.setWidgets(widgets);
JAXBContext context = JAXBContext.newInstance(Test.class);
Marshaller m = context.createMarshaller();
m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
m.marshal(t, System.out);

This is the output:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<test>
    <widgets/>
    <widgets/>
    <widgets/>
</test>

Answer 1

Your JAXB (JSR-222) implementation can’t determine the subclasses of Widget using reflection, so you will need to include them when you create your JAXBContext.

JAXBContext context = JAXBContext.newInstance(Test.class, Button.class, Label.class);