Changing node name of xml-node with Java

Question

I have following scenario: I have a XML-Document, e.g. like this

<someRootElement>
<tag1>
    <tag2 
        someKey=someValue
        someKey2=someValue2
    />
    <tag3/>
    <tag4
        newKey=newValue
        newKey2=newValue2
    />
</tag1>
</someRootElement>

Now I want the parent tag1 to be called reallyCoolTag without losing the childnodes. I tried the following, but it unfortunately doesn't work as I wish it would (but I do know why, b/c it is missing something, I guess):

// the new element:
Element neu = doc.createElement( newValue );
// append it to the root:
root.appendChild( neu );
// get all the child nodes:
NamedNodeMap nnm = nodes.item(i).getAttributes();
for( int dg = 0; dg < nnm.getLength(); dg++ ){
    neu.setAttribute(  nnm.item( dg ).getNodeName(),
    nnm.item( dg ).getNodeValue() );
}
//---------------------------------------------------------
// HERE I GUESS I AM MISSING THE PART WHERE THE CHILD NODES
// ARE BEING APPENDED TO THE NEW NODE?????
//---------------------------------------------------------
// nodes.item(i) := the old value (nodes := is a NodeList
root.replaceChild( neu, nodes.item(i));
TransformerFactory tFactory     = TransformerFactory.newInstance();
Transformer transformer         = tFactory.newTransformer();
DOMSource source                = new DOMSource( doc );
StreamResult result         = new StreamResult( xml );
transformer.transform( source, result );
nodes.item( i ).getParentNode().removeChild( nodes.item(i) );

Now this does work to a certain extend, as I mentioned, I guess I am missing the part where the child nodes are being appened, but what I actually wanted to know is, whether there is a really short way to rename the parent node without having to copy everything and replace the whole thing?

Thnx in advance!!!

Answer 1

Using Document.renameNode:

NodeList nodes = document.getElementsByTagName("tag1");
for (Node eachNode: nodes) {
  document.renameNode(eachNode, null, "reallyCoolTag");
}

Answer 2

Just call setName("reallyCoolTag") on the element(s) you want to rename. There is no need to copy the children around; the name attribute of an element is a mutable field.

Answer 3

Your tag1 is invalid. It doesn't have closing >. Also the attributes should be quoted. It should look like this,

<someRootElement>
<tag1>
    <tag2 
        someKey="someValue"
        someKey2="someValue2"
    />
    <tag3/>
    <tag4
        newKey="newValue"
        newKey2="newValue2"
    />
</tag1>
</someRootElement>

Try with the corrected XML. It should work.

Answer 4

As you did get the attributes:

NamedNodeMap nnm = nodes.item(i).getAttributes();

and you added these attributes to the new element,

You should get the children of nodes.item(i) and set them in the new node.

You can use for ex.:

neu.addContent(nodes.item(i).getChildren());

Answer 5

You could use an XSL Transformation (XSLT) for this:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  version="1.0">
  <xsl:output method="xml" indent="yes" />
  <xsl:template match="*"> <!-- match anything -->
    <xsl:copy>
      <xsl:copy-of select="@*" />
      <xsl:apply-templates />
    </xsl:copy>
  </xsl:template>
  <xsl:template match="tag1"> <!-- switch the element name -->
    <xsl:element name="reallyCoolTag">
      <xsl:copy-of select="@*" />
      <xsl:apply-templates />
    </xsl:element>
  </xsl:template>
</xsl:stylesheet>

This can be used with the javax.xml.transform package (Java 1.4 and above):

TransformerFactory transFactory = TransformerFactory.newInstance();
Transformer transformer = transFactory.newTransformer(new StreamSource(
    new File("RenameTag.xslt")));
transformer
    .transform(new DOMSource(document), new StreamResult(System.out));

See DOMResult if you want a Document as the output.