How to remove extra empty lines from XML file?

You could look at something like this if you only need to "clean" your xml quickly. Then you could have a method like:

public static String cleanUp(String xml) {
    final StringReader reader = new StringReader(xml.trim());
    final StringWriter writer = new StringWriter();
    try {
        XmlUtil.prettyFormat(reader, writer);
        return writer.toString();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return xml.trim();
}

Also, to compare anche check differences, if you need it: XMLUnit

I was able to fix this by using this code after removing all the old "path" nodes :

while( pathsElement.hasChildNodes() )
    pathsElement.removeChild( pathsElement.getFirstChild() );

This will remove all the generated empty spaces in the XML file.

Special thanks to MadProgrammer for commenting with the helpful link mentioned above.

First, an explanation of why this happens — which might be a bit off since you didn't include the code that is used to load the XML file into a DOM object.

When you read an XML document from a file, the whitespaces between tags actually constitute valid DOM nodes, according to the DOM specification. Therefore, the XML parser treats each such sequence of whitespaces as a DOM node (of type TEXT);

To get rid of it, there are three approaches I can think of:

• Associate the XML with a schema, and then use setValidating(true) along with setIgnoringElementContentWhitespace(true) on the DocumentBuilderFactory.

  (Note: setIgnoringElementContentWhitespace will only work if the parser is in validating mode, which is why you must use setValidating(true))

• Write an XSL to process all nodes, filtering out whitespace-only TEXT nodes.

• Use Java code to do this: use XPath to find all whitespace-only TEXT nodes, iterate through them and remove each one from its parent (using getParentNode().removeChild()). Something like this would do (doc would be your DOM document object):

  XPath xp = XPathFactory.newInstance().newXPath();
  NodeList nl = (NodeList) xp.evaluate("//text()[normalize-space(.)='']", doc, XPathConstants.NODESET);
  
  for (int i=0; i < nl.getLength(); ++i) {
      Node node = nl.item(i);
      node.getParentNode().removeChild(node);
  }