Unwanted Dom4J Namespace

Question

When creating a document with a default namespace <root xmlns="....">using DOM4J, I get the following output on writing to file.

<?xml version="1.0" encoding="UTF-8"?>

<root xmlns="http:/foo.bar">
  <foo xmlns="">bar</foo> <!-- unwanted xmlns="" on foo -->
</root>

What I expected (and want) is for foo to be <foo> not <foo xmlns="">. Here is some demo code

import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.Namespace;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;

public class App {

    public static void main(String[] args) throws Exception {
        Namespace xmlns = DocumentHelper.createNamespace("", "http:/foo.bar");
        Element root = DocumentHelper.createElement("root");
        root.add(xmlns);

        Document document = DocumentHelper.createDocument();
        document.setRootElement(root);

        Element child = DocumentHelper.createElement("foo");
        child.setText("bar");
        root.add(child);

        OutputFormat format = OutputFormat.createPrettyPrint();
        XMLWriter writer = new XMLWriter( System.out, format );
        writer.write( document );
    }
}

How do I remove the extra attribute from <foo>? I'm happy to use a different library if that would be easier.

SOLUTION

The answer below together with this question helped solve my issue. I have also included the corrected code below:

import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.Namespace;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;

public class App {

    public static void main(String[] args) throws Exception {
        Document document = DocumentHelper.createDocument();
        Element root = document.addElement("root");

        Namespace xmlns = Namespace.get("http:/foo.bar");
        root.add(xmlns);

        root.addElement("foo", "http:/foo.bar")
                .addText("bar");

        OutputFormat format = OutputFormat.createPrettyPrint();
        XMLWriter writer = new XMLWriter( System.out, format );
        writer.write( document );
    }
}

Answer 1

Are you saying that you want every node in the tree to be in the same namespace?

The code posted above clearly directs the library to put the child element foo in a different namespace (in this case, the default or null namespace) from its parent. So the serialized XML reflects this fact! If you want "foo" to be in the same namespace you'll have to assign it properly.

If you just want a single namespace, I suggest looking into assigning the default namespace in dom4j.