Having trouble formatting multiple nodes from a text to XML conversion in Java

Question

I have a Java program which converts text files to XML. I need the following format:

    <app:defaults>
    <app:schedules>
    <app:run>
    <app:schedule>schedule frequency value</app:schedule>
    </app:run>
    </app:schedules>
    <app:rununit>
    <app:agent>agent hostname value</app:agent>
    </app:rununit> 
    </app:defaults>

The ending "/app:schedules" tag is not appending in the correct place after the "/app:run" tag. The program is instead generating the following (which is not correct):

   <app:defaults>
   <app:schedules>
   <app:run>
   <app:schedule>schedule frequency value</app:schedule>
   </app:run>
   <app:rununit>
   <app:agent>agent hostname value</app:agent>
  </app:rununit> 
  </app:schedules>
 </app:defaults>

The method in the java program is as follows: for this example i expilicitly added the text to each node to show what the data should be. - this method takes String args otherwise from the input text file.

 public static void main(String[] args) {
  String infile = args[0];
  String outxml = args[1];

 BufferedReader in;
 StreamResult out;

 DocumentBuilderFactory icFactory = DocumentBuilderFactory.newInstance();
  DocumentBuilder icBuilder;
  try {
    in = new BufferedReader(new FileReader(infile));
    out = new StreamResult(outxml);

    icBuilder = icFactory.newDocumentBuilder();
    Document doc = icBuilder.newDocument();
    Element mainRootElement = doc.createElementNS ("http://dto.cybermation.com/application", "app:appl");
    mainRootElement.setAttribute("name", "TESTSHEDULE");
    doc.appendChild(mainRootElement);

                 ...

       private static Node processTagElements3(Document doc, String "app:defaults") {

        Element node1 = doc.createElement("app:schedules");
        Element node2 = doc.createElement("app:run");
        Element node3 = doc.createElement("app:schedule");
        Element node4 = doc.createElement("app:rununit");
        Element node5 = doc.createElement("app:agent");

        node1.appendChild(node2);
        node2.appendChild(node3);
        node3.appendChild(doc.createTextNode("schedule frequency value"));
        node1.appendChild(node4);
        node4.appendChild(node5);
        node5.appendChild(doc.createTextNode("agent hostname value"));

    return node1;
}

I've tested this using different appenchild parameters between these nodes but ran up against a brick wall with formatiing this output. Any suggestions, advice on the best way to organize the node tag insertions is really appreciated. There could be somthing simple I am missing.

Answer 1

Note: I'm not an expert in for XML parsing in Java.

Just trying to stitch some example codes I got in my machine and see if that solves your problem. So here it is.

Example code:

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import java.io.StringReader;
import java.io.StringWriter;\

public class test {

    public static void main(String[] args) throws Exception {

        String xml = "<app:defaults>\n" +
                "    <app:schedules>\n" +
                "    <app:run>\n" +
                "    <app:schedule>schedule frequency value</app:schedule>\n" +
                "    </app:run>\n" +
                "    </app:schedules>\n" +
                "    <app:rununit>\n" +
                "    <app:agent>agent hostname value</app:agent>\n" +
                "    </app:rununit> \n" +
                "    </app:defaults>";
        Document doc = DocumentBuilderFactory.newInstance().newDocumentBuilder()
                .parse(new InputSource(new StringReader(xml)));

        NodeList errNodes = doc.getElementsByTagName("error");
        if (errNodes.getLength() > 0) {
            Element err = (Element)errNodes.item(0);
            System.out.println(err.getElementsByTagName("errorMessage")
                    .item(0).getTextContent());
        } else {
            // success
            DOMSource domSource = new DOMSource(doc);
            StringWriter writer = new StringWriter();
            StreamResult result = new StreamResult(writer);
            TransformerFactory tf = TransformerFactory.newInstance();
            Transformer transformer = tf.newTransformer();
            transformer.transform(domSource, result);

            System.out.println(writer.toString());
        }
}

Output:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
  <app:defaults>
    <app:schedules>
      <app:run>
        <app:schedule>schedule frequency value</app:schedule>
      </app:run>
    </app:schedules>
    <app:rununit>
      <app:agent>agent hostname value</app:agent>
    </app:rununit> 
  </app:defaults>

This code seems to be working as what you will expecting it to be. Give it a try and let me know whether the solution is okay.

I think the idea here is to use pre-baked Java APIs than writing our own parser. Because these APIs are generally more reliable since many others would be using it daily.

Answer 2

Things would be way easier if you had named your nodes with meaningful names (let's say runNode , etc), don't you think?

That being said, this is probably what you want:

    Element defaultNode = doc.createElement("app:default");
    Element schedulesNode = doc.createElement("app:schedules");
    Element runNode = doc.createElement("app:run");
    Element scheduleNode = doc.createElement("app:schedule");
    Element rununitNode = doc.createElement("app:rununit");
    Element agentNode = doc.createElement("app:agent");

    defaultNode.appendChild(schedulesNode);
    schedulesNode.appendChild(runNode);
    runNode.appendChild(scheduleNode);
    scheduleNode.appendChild(doc.createTextNode("schedule frequency value"));
    defaultNode.appendChild(rununitNode);
    rununitNode.appendChild(agentNode);
    agentNode.appendChild(doc.createTextNode("agent hostname value"));

Note the defaultNode used.

Answer 3

Thanks all! I decided to modify the script to accept file input as my arg - this works fine now and is a simpler solution:

public class test2 {

public static void main(String[] args) throws Exception {
      File file = new File(args[0]);

 DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
try{
 DocumentBuilder builder = factory.newDocumentBuilder();

  FileInputStream fis = new FileInputStream(file);
     InputSource is = new InputSource(fis);
     Document doc = builder.parse(is);

    NodeList errNodes = doc.getElementsByTagName("error");
    if (errNodes.getLength() > 0) {
        Element err = (Element)errNodes.item(0);
        System.out.println(err.getElementsByTagName("errorMessage").item(0).getTextContent());
    } else {
  // success
        DOMSource domSource = new DOMSource(doc);
        StringWriter writer = new StringWriter();
        StreamResult result = new StreamResult(writer);
        TransformerFactory tf = TransformerFactory.newInstance();
        Transformer transformer = tf.newTransformer();
        transformer.transform(domSource, result);

        System.out.println(writer.toString());
          }
        } catch (Exception e) {
        e.printStackTrace();
        }
      }
    }