Pretty print XML in java 8

Question

I have an XML file stored as a DOM Document and I would like to pretty print it to the console, preferably without using an external library. I am aware that this question has been asked multiple times on this site, however none of the previous answers have worked for me. I am using java 8, so perhaps this is where my code differs from previous questions? I have also tried to set the transformer manually using code found from the web, however this just caused a not found error.

Here is my code which currently just outputs each xml element on a new line to the left of the console.

import java.io.*;
import javax.xml.parsers.*;
import javax.xml.transform.*;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;


public class Test {
    public Test(){
        try {
            //java.lang.System.setProperty("javax.xml.transform.TransformerFactory", "org.apache.xalan.xsltc.trax.TransformerFactoryImpl");

            DocumentBuilderFactory dbFactory;
            DocumentBuilder dBuilder;
            Document original = null;
            try {
                dbFactory = DocumentBuilderFactory.newInstance();
                dBuilder = dbFactory.newDocumentBuilder();
                original = dBuilder.parse(new InputSource(new InputStreamReader(new FileInputStream("xml Store - Copy.xml"))));
            } catch (SAXException | IOException | ParserConfigurationException e) {
                e.printStackTrace();
            }
            StringWriter stringWriter = new StringWriter();
            StreamResult xmlOutput = new StreamResult(stringWriter);
            TransformerFactory tf = TransformerFactory.newInstance();
            //tf.setAttribute("indent-number", 2);
            Transformer transformer = tf.newTransformer();
            transformer.setOutputProperty(OutputKeys.METHOD, "xml");
            transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4");
            transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "no");
            transformer.setOutputProperty(OutputKeys.INDENT, "yes");
            transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
            transformer.transform(new DOMSource(original), xmlOutput);
            java.lang.System.out.println(xmlOutput.getWriter().toString());
        } catch (Exception ex) {
            throw new RuntimeException("Error converting to String", ex);
        }
    }

    public static void main(String[] args){
        new Test();
    }

}

Answer 1

I guess that the problem is related to blank text nodes (i.e. text nodes with only whitespaces) in the original file. You should try to programmatically remove them just after the parsing, using the following code. If you don't remove them, the Transformer is going to preserve them.

original.getDocumentElement().normalize();
XPathExpression xpath = XPathFactory.newInstance().newXPath().compile("//text()[normalize-space(.) = '']");
NodeList blankTextNodes = (NodeList) xpath.evaluate(original, XPathConstants.NODESET);

for (int i = 0; i < blankTextNodes.getLength(); i++) {
     blankTextNodes.item(i).getParentNode().removeChild(blankTextNodes.item(i));
}