How to setup ArrayList<String>

Question

I am trying to run this code and ArrayList data = handler.getnames(); is showing an error variable data is alredy defined in method main(String[]). I am guessing it wants me to combine it with ArrayList data = handler.getsetnums();. But how to i do it? or is there another way?
Ones the code works, and should be able to run it and get an output, now when i only have one Array working the code does what it needs to do.

expected outcome

<set-num>00-1</set-num>
<name>WEETABIX CASTLE</name>

Thank you.

---MAIN.java---
package assign6;

    import java.io.IOException;
    import java.util.ArrayList;
    import java.util.logging.Level;
    import java.util.logging.Logger;
    import org.xml.sax.InputSource;
    import org.xml.sax.SAXException;
    import org.xml.sax.XMLReader;
    import org.xml.sax.helpers.XMLReaderFactory;

    /**
     *
     * @author assign
     */
    public class Assign6 {

        /**
         * @param args the command line arguments
         */
        public static void main(String[] args) {
            System.out.print("Welcome to Benjamin Bolyard's Lego Sorter");
            try {
                XMLReader reader = XMLReaderFactory.createXMLReader();
                MyHandler handler = new MyHandler();
                reader.setContentHandler(handler);
                reader.setErrorHandler(handler);

                InputSource inputSource = new InputSource("legoSets.xml");
                reader.parse(inputSource);

                ArrayList<String> data = handler.getsetnums();

                System.out.println("setnum List");
                System.out.println("----------");
                for (int i = 0; i < data.size(); i++) {
                    String setnum = data.get(i);
                    setnum = setnum.toUpperCase();
                    System.out.println((i + 1) + ": " + setnum);
                }

                ArrayList<String> data = handler.getnames();

                System.out.println("name List");
                System.out.println("----------");
                for (int i = 0; i < data.size(); i++) {
                    String name = data.get(i);
                    name = name.toUpperCase();
                    System.out.println((i + 1) + ": " + name);
                }

            } catch (SAXException ex) {
                Logger.getLogger(BolyardAssign6.class.getName())
                        .log(Level.SEVERE, null, ex);
            } catch (IOException ex) {
                Logger.getLogger(BolyardAssign6.class.getName())
                        .log(Level.SEVERE, null, ex);
            }
        }

    }
--HANDLER.java---
/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package bolyardassign6;

import java.util.ArrayList;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.helpers.DefaultHandler;

/**
 *
 * @author bolya
 */
public class MyHandler extends DefaultHandler {

    private boolean inlegosets;
    private boolean inname;
    private boolean insetnum;
    private String nameBuffer;
    private String setnumBuffer;

     private ArrayList<String> setnums, names;

    public ArrayList<String> getsetnums() {
        return setnums;

    }

    public ArrayList<String> getnames() {
        return names;
    }

    @Override
    public void startDocument() throws SAXException {
        // System.out.println("Start Document")
        insetnum = false;
        inname = false;
        inlegosets = false;
        nameBuffer = "";
        names = new ArrayList<>();
    }

    @Override
    public void startElement(String uri, String localName,
            String qName, Attributes attributes) throws SAXException {
        if (localName.equals("lego-sets")) {
            inlegosets = true;
        } else if (inlegosets && localName.equals("setnum")) {
            // System.out.println("Start element : " + localName);
            insetnum = true;
            setnumBuffer = "";

        } else if (inlegosets && localName.equals("name")) {
            // System.out.println("Start element : " + localName);
            inname = true;
            nameBuffer = "";
        }
    }

    @Override
    public void characters(char[] ch, int start, int length) throws SAXException {
        String data = new String(ch, start, length);
        if (inlegosets && inname) {
            // System.out.println("Characters : " + data);
            nameBuffer = nameBuffer + data;
        } else if (inlegosets && insetnum) {
            // System.out.println("Characters : " + data);
            setnumBuffer = setnumBuffer + data;
    }
    }

    @Override
    public void endElement(String uri, String localName,
            String qName) throws SAXException {
        if (localName.equals("inlegosets")) {
            inlegosets = false;
        } else if (inlegosets && localName.equals("setnum")) {
            // System.out.println("Title: " + titleBuffer);
            // System.out.println("End element   : " + localName);
            // System.out.println();            
            setnums.add(setnumBuffer);
            insetnum = false;
        } else if (inlegosets && localName.equals("name")) {
            // System.out.println("Title: " + titleBuffer);
            // System.out.println("End element   : " + localName);
            // System.out.println();            
            names.add(nameBuffer);
            inname = false;
        }
    }

    @Override
    public void endDocument() throws SAXException {
        // System.out.println("End Document");
    }

    @Override
    public void error(SAXParseException e) throws SAXException {
        System.out.println("ERROR: Line number " + e.getLineNumber());
        System.out.println("ERROR:             " + e.getMessage());
    }

    @Override
    public void fatalError(SAXParseException e) throws SAXException {
        System.out.println("FATAL ERROR: Line number " + e.getLineNumber());
        System.out.println("FATAL ERROR:             " + e.getMessage());
    }

}

---legoset.xml---
<lego-sets>
    <set>
        <set-num>00-1</set-num>
        <name>WEETABIX CASTLE</name>
        <year>1970</year>
        <num-parts>471</num-parts>
    </set>
    <set>
        <set-num>0011-2</set-num>
        <name>TOWN MINI-FIGURES</name>
        <year>1978</year>
        <num-parts>12</num-parts>
    </set>
    <set>
        <set-num>0011-3</set-num>
        <name>CASTLE 2 FOR 1 BONUS OFFER</name>
        <year>1987</year>
        <num-parts>2</num-parts>
    </set>
    <set>
        <set-num>0012-1</set-num>
        <name>SPACE MINI-FIGURES</name>
        <year>1979</year>
        <num-parts>12</num-parts>
    </set>
</lego-sets>

Answer 1

I am trying to run this code and ArrayList data = handler.getnames(); is showing an error variable data is alredy defined in method main(String[]). I am guessing it wants me to combine it with ArrayList data = handler.getsetnums();. But how to i do it? or is there another way?

You have the right idea. The error is caused because you have two variable declarations withe same name:

ArrayList data = handler.getnames()

and

ArrayList data = handler.getsetnums();

Java doesn't allow this. However, you don't necessarily want to "combine them together" because these are two separate lists that seem to represent two different things.

I suggest changing the names of both variables to something more meaningful than data. For example:

ArrayList names = handler.getnames()

and

ArrayList setnums = handler.getsetnums();

Presumably, names and setnums represent something meaningful for what you are doing here.

Answer 2

You have defined two variables with the name data. To fix this, change the name of one of them. Alternatively you can remove the declaration and just have the following on the second arraylist: data = handler.getnames();