Android SAX Parser - Same tag names on several levels

Question

I've been looking for a solution in order to parse my xml that has same tag names on several levels. Here is a XML sample of what I have to work on (the sections are not static):

<xml>
  <section id="0">
     <title>foo</title>
     <section id="1">
        <title>sub foo #1</title>
        <section id="2">
          <title>sub sub foo</title>
        </section>
     </section>
     <section id="3">
        <title>sub foo #2</title>
     </section>
  </section>
<xml>

I have been trying several possibilities, such as trying Lists, Stacks, but what I have done with SAX hasn't produced anything correct yet; in other words I'm stuck :(

I created a class called Section:

public class Section {
public String id;
public String title;
public List<Section> sections; }

I'm wondering if I should also add a parent variable?

public Section parent;

If anyone has a solution, I thank you very much! :D

Answer 1

Indeed you likely need at least a stack for this.

With (I hope) clear changes to your Section class (setters/getters and a method to add a section), this handler seems to do the trick:

Since your layout appears to allow for multiple <section> tags immediately below the <xml> root, I've implemented it also putting the results into a List<Section>.

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import java.util.ArrayList;
import java.util.List;
import java.util.Stack;

public class SectionXmlHandler extends DefaultHandler {

    private List<Section> results;
    private Stack<Section> stack;
    private StringBuffer buffer = new StringBuffer();

    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        if ("xml".equals(localName)) {
            results = new ArrayList<Section>();
            stack = new Stack<Section>();
        } else if ("section".equals(localName)) {
            Section currentSection = new Section();
            currentSection.setId(attributes.getValue("id"));
            stack.push(currentSection);
        } else if ("title".equals(localName)) {
            buffer.setLength(0);
        }
    }

    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
        if ("section".equals(localName)) {
            Section currentSection = stack.pop();
            if (stack.isEmpty()) {
                results.add(currentSection);
            } else {
                Section parent = stack.peek();
                parent.addSection(currentSection);
            }
        } else if ("title".equals(localName)) {
            Section currentSection = stack.peek();
            currentSection.setTitle(buffer.toString());
        }
    }

    @Override
    public void characters(char[] ch, int start, int length) throws SAXException {
        buffer.append(ch, start, length);
    }

    public List<Section> getResults() {
        return results;
    }
}