Question

In this method, an XML file is read and certain information about it is put into a list. I have everything else working for all of the code/other methods, I am just having trouble returning the “list” variable.

package ca3;

import java.io.File;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import org.w3c.dom.Document;
import org.w3c.dom.*;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;

public class xmlReader{

    public String fileName;
    public xmlReader (String fileLoca){
        fileName=fileLoca;
    }

    public List list;

    public List returnLists(String fileN)
    {
        mp3Lister woww = null;
        String fName;
        String lName;
        mp3Lister qwewq;
    try {
            DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();
            DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();
            Document doc = docBuilder.parse (new File(fileN));

            // normalize text representation
            doc.getDocumentElement ().normalize ();
            System.out.println ("Root element of the doc is " +
                 doc.getDocumentElement().getNodeName());

            NodeList listOfPersons = doc.getElementsByTagName("person");
            int totalPersons = listOfPersons.getLength();
            System.out.println("Total no of people : " + totalPersons);
            List list = new LinkedList();    // Doubly-linked list

            for(int s=0; s<listOfPersons.getLength() ; s++){
                Node firstPersonNode = listOfPersons.item(s);
                if(firstPersonNode.getNodeType() == Node.ELEMENT_NODE){
                    Element firstPersonElement = (Element)firstPersonNode;

                    //-------
                    NodeList firstNameList = firstPersonElement.getElementsByTagName("first");
                    Element firstNameElement = (Element)firstNameList.item(0);

                    NodeList textFNList = firstNameElement.getChildNodes();
//                    System.out.println("First Name : " +
//                           ((Node)textFNList.item(0)).getNodeValue().trim());

//                            
                    //-------
                    NodeList lastNameList = firstPersonElement.getElementsByTagName("last");
                    Element lastNameElement = (Element)lastNameList.item(0);

                    NodeList textLNList = lastNameElement.getChildNodes();
//                    System.out.println("Last Name : " +
//                           ((Node)textLNList.item(0)).getNodeValue().trim());

                    lName = textLNList.item(0).getNodeValue().trim().toString();
                    fName = textFNList.item(0).getNodeValue().trim().toString();
                    mp3Lister[] wowow = null;

                    woww = new mp3Lister(fName,lName);

                    list.add(woww);
                    //----

                    //------

                }//end of if clause

//                qwewq = (mp3Lister) list.get(0);
//                System.out.println(qwewq.getTitle() + " wakakakakaka");

            }//end of for loop with s var
            //end of for loop with s var

        }catch (SAXParseException err) {
        System.out.println ("** Parsing error" + ", line "
             + err.getLineNumber () + ", uri " + err.getSystemId ());
        System.out.println(" " + err.getMessage ());

        }catch (SAXException e) {
        Exception x = e.getException ();
        ((x == null) ? e : x).printStackTrace ();

        }catch (Throwable t) {
        t.printStackTrace ();
        }

return list;
        //System.exit (0);

    }
}

Answer 1

I assume that you meant to return the list local variable that you declare in the returnLists function. What you’ll be getting back is actually the class variable, also called list. This is because the local list variable has gone out of context by the time the code reaches your return statement (the local list variable is within the context of the try block you have declared). If you want to return the value from the local list variable change the first couple of lines of returnLists to this:

public List returnLists(String fileN)
    {
        mp3Lister woww = null;
        String fName;
        String lName;
        mp3Lister qwewq;
        List list = new LinkedList();
    try {

and then remove the declaration of the list variable inside the try block.