Question

I have a Jtable which uses custom renderer and editor, which use JTextPane as editor and renderer, which uses DefaultStyledDocument as the text model. The table contains hyperlinks, which are text with HTML.Attribute.HREF attribute. In order to save this styled text into database I need to convert the DefaultStyledDocument into XML and trying to do that throws this exception:

javax.swing.text.html.HTML$Attribute is not serializable as a key in an AttributeSet.

How can I fix this?

Answer 1

HTML.Attribute is not Serializable. For some reason Java developers decided not to add serialization support to HTML.Attribute as well as HTML.Tag. The most probable reason is that HTMLDocument which uses them is serialized into HTML text, and thus there’s no need to serialize Java objects directly.

It’s easy to fix, really. Create your own attribute:

public final class LinkAttribute implements Serializable {
    private static final long serialVersionUID = -472010305643114209L;

    public static final LinkAttribute HREF = new LinkAttribute("href");

    private final String name;

    private LinkAttribute(final String name) {
        this.name = name;
    }

    public boolean equals(final Object o) {
       return o instanceof LinkAttribute
              ? name.equals(((LinkAttribute) o).name)
              : false;
    }

    public int hashCode() {
        return name.hashCode();
    }

    public String toString() {
        return name;
    }
}

This is roughly the implementation of HTML.Attribute class, with Serializable interface added.

Use LinkAttribute.HREF everywhere you used HTML.Attribute.HREF.