Help me with Java

package Model;

import java.util.ArrayList;
import java.util.List;
import javax.swing.table.AbstractTableModel;

public class TableModel extends AbstractTableModel {

    private ArrayList<String> titles;
    private final int columnNumber = titles.size();

    private ArrayList<Object> objectList;




    public TableModel(ArrayList<Object> objectList, ArrayList<String> titles) {
        this.objectList=objectList;
        this.titles=titles;
    }


    public Class getColumnClass(int column) {
        return getValueAt(0, column).getClass();
    }

    public int getListSize() {
        return this.objectList.size();
    }

    public String getColumnName(int col) {
        return titles.get(col);
    }

    @Override
    public int getRowCount() {
        return this.objectList.size();
    }

    @Override
    public int getColumnCount() {
        return columnNumber;
    }

    @Override
    public java.lang.Object getValueAt(int rowIndex, int columnIndex) {
        Object object= objectList.get(rowIndex);
        if(columnIndex<titles.size()){
            return object.getData(columnIndex);
        }
        return "";

    }
}






package Model;


import org.jdom2.Attribute;
import org.jdom2.Document;
import org.jdom2.Element;
import org.jdom2.input.SAXBuilder;

import javax.swing.*;
import java.awt.*;
import java.io.FileReader;
import java.util.ArrayList;

public class LoadTable {

    public ArrayList <Object> objectList = new ArrayList<Object>();
    public ArrayList<String> titles = new ArrayList<String>();


    public LoadTable(){

        Object object;

        FileDialog loadDia = new FileDialog(new JFrame(), "Choose a file",
                FileDialog.LOAD);
        loadDia.setDirectory("C:\\Users\\AskeRik\\Desktop\\");
        loadDia.setVisible(true);
        String filename = loadDia.getFile();
        if (filename == null) {
            JOptionPane.showMessageDialog(null, "error");
        } else {
            filename = loadDia.getDirectory() + filename;
            try {
                SAXBuilder parser = new SAXBuilder();
                FileReader fr = new FileReader(filename);
                Document rDoc = parser.build(fr);

                ArrayList <String> data = new ArrayList<String>();
                java.util.List<Element> temp = rDoc.getRootElement().getChildren();
                java.util.List<Attribute> names = temp.get(0).getAttributes();
                for (int i = 0; i< names.size(); i++){
                    titles.add(names.get(i).getName());

                }

                for (int i = 0; i<titles.size(); i++){
                    //System.out.println(titles.get(i));
                }

                for (int mark = 0; mark < temp.size(); mark++) {
                    java.util.List<Attribute> atrs = temp.get(mark).getAttributes();
                    for (int number = 0; number <atrs.size(); number++) {
                        data.add(atrs.get(number).getValue());
                        object = new Object(data);
                        objectList.add(object);
                        data.clear();

                    }

                }


                JFrame mainFrame = new JFrame("table");
                mainFrame.setLayout(new FlowLayout());
                mainFrame.setSize(600,400);
                mainFrame.setVisible(true);
                mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                TableModel tableModel = new TableModel(objectList, titles);
                JTable table = new JTable(tableModel);
                JScrollPane jScrollPane = new JScrollPane(table);
                table.setPreferredScrollableViewportSize(new Dimension(500, 300));
                mainFrame.getContentPane().add(jScrollPane);


            } catch (Exception ex) {
                System.out.println(ex.getMessage());
            }
        }
    }
}