SAX parsing and loops problem

Question

Hi!
I currently have an XML file which looks like this:
<jel>
<admin creation="Fri Nov 09 17:14:55 GMT 2007" xsdversion="1.0.0" version="1.0.0"/>
&#8722;
     <jelclass superclass="Object" visibility="public" package="" superclassfulltype="java.lang.Object" fulltype="Player" type="Player">
&#8722;
     <implements>
<interface fulltype="java.awt.event.ActionListener" type="ActionListener"/>
<interface fulltype="java.awt.event.KeyListener" type="KeyListener"/>
</implements>
&#8722;
     <methods>
&#8722;
     <constructor visibility="public" name="Player">
&#8722;
     <params>
<param name="newProtocol" fulltype="NewProtocol" type="NewProtocol"/>
<param name="x" fulltype="int" type="int"/>
<param name="y" fulltype="int" type="int"/>
</params>
</constructor>
&#8722;
     <method visibility="public" name="actionPerformed" fulltype="void" type="void">
&#8722;
     <params>
<param name="e" fulltype="java.awt.event.ActionEvent" type="ActionEvent"/>
</params>
</method>
&#8722;
     <method visibility="public" name="keyPressed" fulltype="void" type="void">
&#8722;
     <params>
<param name="e" fulltype="java.awt.event.KeyEvent" type="KeyEvent"/>
</params>
</method>
&#8722;
     <method visibility="public" name="keyReleased" fulltype="void" type="void">
&#8722;
     <params>
<param name="e" fulltype="java.awt.event.KeyEvent" type="KeyEvent"/>
</params>
</method>
&#8722;
     <method visibility="public" name="keyTyped" fulltype="void" type="void">
&#8722;
     <params>
<param name="e" fulltype="java.awt.event.KeyEvent" type="KeyEvent"/>
</params>
</method>
<method visibility="public" name="getX" fulltype="int" type="int"/>
&#8722;
     <method visibility="public" name="setX" fulltype="void" type="void">
&#8722;
     <params>
<param name="x" fulltype="int" type="int"/>
</params>
</method>
<method visibility="public" name="getY" fulltype="int" type="int"/>
&#8722;
     <method visibility="public" name="setY" fulltype="void" type="void">
&#8722;
     <params>
<param name="y" fulltype="int" type="int"/>
</params>
</method>
</methods>
</jelclass>And I have SAX parsing code that looks like this:
public class SaxParser{
      private HashSet <String>packageSet = new HashSet<String>();
      private ArrayList <String> classList = new ArrayList<String>();
      private ArrayList <String> packageList = new ArrayList<String>();
      private ArrayList <String> methodList = new ArrayList<String>();
      private Object[] packageNames;
      private HashMap <String, ArrayList> h = new HashMap <String, ArrayList>();
      public SaxParser()throws Exception{
          String fname = "eclipse/jel.xml";
         DefaultHandler handler = new DefaultHandler()
             private int numberOfClasses = 0;
         public void startElement(String namespaceURI,String localName, String qname, Attributes attrs)
              if(qname.equals("jelclass")) {
                   numberOfClasses ++;
              for(int i = 0; i< attrs.getLength();i++){
                    if(attrs.getQName(i).equals("type")){
                         classList.add(attrs.getValue(i));
                         if(attrs.getQName(i).equals("package")){
                              packageList.add(attrs.getValue(i));
                              packageSet.add(attrs.getValue(i));
              for(int i = 0; i< attrs.getLength();i++){
                   for(int j = 0; j < classList.size(); j++){
          if(attrs.getQName(i).equals("type") && attrs.getValue(i).equals(classList.get(j))){
              if(qname.equals("method")){
                    if(attrs.getQName(i).equals("name")){
                                h.put(classList.get(i), methodList.add(attrs.getValue(i));
               packageNames = new String[packageSet.size()];
              packageNames = packageSet.toArray();
         public void endElement(String namespaceURI,String localName, String qname){}};
        SAXParserFactory factory = SAXParserFactory.newInstance();
        SAXParser saxParser = factory.newSAXParser();
        saxParser.parse(new File(fname), handler);
     public int getPackageNumber(){
          return packageSet.size();
     public Object[] getPackageNames(){
          return packageNames;
     public ArrayList getPackageList(){
          return packageList;
     public ArrayList getClassList(){
          return classList;
     public ArrayList getMethodList(){
          return methodList;
      public static void main(String[] args)throws Exception{
           new SaxParser();
}I am currently pulling out the package names, pulling out the classnames and then mapping these in a separate class - this works because the class and package names are declared in the same line, so if a package name appears in the package list 7 times, i know this package has 7 classes, and therefore i count the first 7 classes out of an array of all the classes and know that these are the right 7 for that package. However, the methods are a bit different:
What I would like to do is to: for every class make a hashmap which maps the class name onto an arraylist of the methods, but i think i'm getting confused with my for loops. Or even just keep a tally of how many methods each class has, then I can work it out as i did with the packages -> classes.
Does anyone know where im going wrong, or have any ideas at all?
Thank you for your time,
beccy
:)

Answer 1

I don't know if stacks are specifically mentioned in any SAX documentation.
Basically, SAX sends you a stream of XML elements (open and close tags, characters, etc.), but it doesn't know anything about the underlying XML structure. You have to add that part (usually -- sometimes when writing a SAX application, you don't really care about the XML structure). XML structure is a tree.
If you've ever written a recursive function that spans a tree, you'll have an idea what to do. You can use a stack to keep track of where you are in the tree. For example, if you open tag A, then you're "in" the A element for subsequent content in that document; if you then open tag B, you're in the B element; but when you close the B tag, you need the stack to tell you that now you're back in the A element.
You may not need stacks, but it's likely. Find a good tutorial about SAX that mentions stacks and you'll be fine.
Edited by: paulcw on Nov 14, 2007 4:09 PM