Find elements and add a child PI : Processing Instruction « XML « Java Tutorial

1. Java Tutorial
2. XML
3. Processing Instruction

import java.io.File;

import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.w3c.dom.ProcessingInstruction;

public class Main {
  public static void main(String[] argv) throws Exception {
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    factory.setValidating(true);

    factory.setExpandEntityReferences(false);

    Document doc = factory.newDocumentBuilder().parse(new File("filename"));

    Element element = doc.getDocumentElement();
    ProcessingInstruction pi = doc.createProcessingInstruction("target", "instruction");

    NodeList list = doc.getElementsByTagName("entry");
    for (int i = 0; i < list.getLength(); i++) {
      element = (Element) list.item(i);
      pi = doc.createProcessingInstruction("target", "instruction=" + i);
      element.appendChild(pi);
    }

  }
}