JTable sorting - problem when adding elements (complete code inside)

Question

I�m writing this email with reference to a recent posting here but this time with the code example. (I apologize for the duplicated posting � this time it will be with the code)
Problem: when adding more elements to the JTable (sorted) the exception: ArrayIndexOutOfBoundsException is thrown.
Example: If the elements in the table are 10 and then the user requests for 8 � the table will produce the correct result. However, if the user will ask for 11 items (>10) the exception will be thrown.
The program: The program below (compiles and running). A JTable is constructed with 3 items, when you click the button - the return result should be 4 items - this will generate the error, WHY?
I would highly appreciate your thoughts why this is happening and most importantly � how to fix it.
Thanks a lot
3 files:
(1) TableSorterDemo
(2) Traveler
(3)TableSorter
//TableSorterDemo:
package sorter;
import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.AbstractTableModel;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
* TableSorterDemo is like TableDemo, except that it
* inserts a custom model -- a sorter -- between the table
* and its data model.  It also has column tool tips.
public class TableSorterDemo implements ActionListener
     private JPanel superPanel;
     private JButton clickMe = new JButton("click me to get diff data");
     private boolean DEBUG = false;
     private DefaultListModel defaultListModel;
     private JTable table;
    public TableSorterDemo()
         superPanel = new JPanel(new BorderLayout());
         defaultListModel = new DefaultListModel();
         init1();
        TableSorter sorter = new TableSorter(new MyTableModel(defaultListModel)); //ADDED THIS     
        table = new JTable(sorter);             //NEW
        sorter.setTableHeader(table.getTableHeader()); //ADDED THIS
        table.setPreferredScrollableViewportSize(new Dimension(500, 70));
        //Set up tool tips for column headers.
        table.getTableHeader().setToolTipText(
                "Click to specify sorting; Control-Click to specify secondary sorting");
        //Create the scroll pane and add the table to it.
        JScrollPane scrollPane = new JScrollPane(table);
        //Add the scroll pane to this panel.
        superPanel.add("Center", scrollPane);
        superPanel.add("South",clickMe);
        clickMe.addActionListener(this);              
    public JPanel getPanel()
         return superPanel;
    public void init1()
         //in real life this will be done from the db
         Traveler a = new Traveler();
         Traveler b = new Traveler();
         Traveler c = new Traveler();
         a.setFirstName("Elvis");
         a.setLastName("Presley");
         a.setSprot("Ping Pong");
         a.setNumYears(3);
         a.setVegetarian(true);
         b.setFirstName("Elton");
         b.setLastName("John");
         b.setSprot("Soccer");
         b.setNumYears(2);
         b.setVegetarian(true);
         c.setFirstName("shaquille");
         c.setLastName("oneil");
         c.setSprot("Golf");
         c.setNumYears(22);
         c.setVegetarian(true);
         defaultListModel.addElement(a);
         defaultListModel.addElement(b);
         defaultListModel.addElement(c);
    public void init2()
         //in real life this will be done from the db
         Traveler d = new Traveler();
         Traveler e = new Traveler();
         Traveler f = new Traveler();
         Traveler g = new Traveler();
         d.setFirstName("John");
         d.setLastName("Smith");
         d.setSprot("Tennis");
         d.setNumYears(32);
         d.setVegetarian(true);
         e.setFirstName("Ron");
         e.setLastName("Cohen");
         e.setSprot("Baseball");
         e.setNumYears(12);
         e.setVegetarian(true);
         f.setFirstName("Donald");
         f.setLastName("Mac Novice");
         f.setSprot("Vallyball");
         f.setNumYears(1);
         f.setVegetarian(true);
         g.setFirstName("Eithan");
         g.setLastName("Superstar");
         g.setSprot("Vallyball");
         g.setNumYears(21);
         g.setVegetarian(true);
         defaultListModel.addElement(d);
         defaultListModel.addElement(e);
         defaultListModel.addElement(f);
         defaultListModel.addElement(g);            
    class MyTableModel extends AbstractTableModel
         private DefaultListModel myModel;
         public MyTableModel(DefaultListModel m)
              myModel=m;
        private String[] columnNames = {"First Name",
                                        "Last Name",
                                        "Sport",
                                        "# of Years",
                                        "Vegetarian"};
        public int getColumnCount()
            return columnNames.length;
        public int getRowCount()
            return myModel.size();
        public String getColumnName(int column)
             return getNames()[column];             
         public String[] getNames()
              String[] names = {"First Name", "Last Name", "Sport", "# of Years", "Vegetarian"};
              return names;
        public Object getValueAt(int row, int col)
             return distributeObjectsInTable(row, col, (Traveler) myModel.elementAt(row));
        public Object distributeObjectsInTable(int row, int col, Traveler tr)
           switch(col)
                     case 0:
                          return tr.getFirstName();
                     case 1:
                       return tr.getLastName();
                  case 2:
                       return tr.getSprot();
                  case 3:
                       return new Integer(tr.getNumYears());
                  case 4:
                       return new Boolean (tr.isVegetarian());
                 default:
                     return "Error";
        public Class getColumnClass(int c)
            return getValueAt(0, c).getClass();
    private static void createAndShowGUI()
        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);
        //Create and set up the window.
        JFrame frame = new JFrame("TableSorterDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        //Create and set up the content pane.
        TableSorterDemo newContentPane = new TableSorterDemo();
        newContentPane.getPanel().setOpaque(true); //content panes must be opaque
        frame.setContentPane(newContentPane.getPanel());
        //Display the window.
        frame.pack();
        frame.setVisible(true);
    public static void main(String[] args)
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable()                   
            public void run()
                createAndShowGUI();
     public void actionPerformed(ActionEvent ae)
          if (ae.getSource()==clickMe)
               defaultListModel.removeAllElements();
               init2(); //if the size of the model was less than 2 items - the result will be ok.
                          //in other words, if you commens the last 2 rows of this method (addElement(f) & g)
                         // the result will be fine.
               table.updateUI();          
}//(2) Traveler
package sorter;
public class Traveler
     private String firstName;
     private String lastName;
     private String sprot;
     private int numYears;
     private boolean vegetarian;
     public String getFirstName()
          return firstName;
     public String getLastName()
          return lastName;
     public int getNumYears()
          return numYears;
     public String getSprot()
          return sprot;
     public boolean isVegetarian()
          return vegetarian;
     public void setFirstName(String firstName)
          this.firstName = firstName;
     public void setLastName(String lastName)
          this.lastName = lastName;
     public void setNumYears(int numYears)
          this.numYears = numYears;
     public void setSprot(String sprot)
          this.sprot = sprot;
     public void setVegetarian(boolean vegetarian)
          this.vegetarian = vegetarian;
}//(3)TableSorter
package sorter;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import java.util.List;
import javax.swing.*;
import javax.swing.event.TableModelEvent;
import javax.swing.event.TableModelListener;
import javax.swing.table.*;
public class TableSorter extends AbstractTableModel {
    protected TableModel tableModel;
    public static final int DESCENDING = -1;
    public static final int NOT_SORTED = 0;
    public static final int ASCENDING = 1;
    private static Directive EMPTY_DIRECTIVE = new Directive(-1, NOT_SORTED);
    public static final Comparator COMPARABLE_COMAPRATOR = new Comparator() {
        public int compare(Object o1, Object o2) {
            return ((Comparable) o1).compareTo(o2);
    public static final Comparator LEXICAL_COMPARATOR = new Comparator() {
        public int compare(Object o1, Object o2) {
            return o1.toString().compareTo(o2.toString());
    private Row[] viewToModel;
    private int[] modelToView;
    private JTableHeader tableHeader;
    private MouseListener mouseListener;
    private TableModelListener tableModelListener;
    private Map columnComparators = new HashMap();
    private List sortingColumns = new ArrayList();
    public TableSorter() {
        this.mouseListener = new MouseHandler();
        this.tableModelListener = new TableModelHandler();
    public TableSorter(TableModel tableModel) {
        this();
        setTableModel(tableModel);
    public TableSorter(TableModel tableModel, JTableHeader tableHeader) {
        this();
        setTableHeader(tableHeader);
        setTableModel(tableModel);
    private void clearSortingState() {
        viewToModel = null;
        modelToView = null;
    public TableModel getTableModel() {
        return tableModel;
    public void setTableModel(TableModel tableModel) {
        if (this.tableModel != null) {
            this.tableModel.removeTableModelListener(tableModelListener);
        this.tableModel = tableModel;
        if (this.tableModel != null) {
            this.tableModel.addTableModelListener(tableModelListener);
        clearSortingState();
        fireTableStructureChanged();
    public JTableHeader getTableHeader() {
        return tableHeader;
    public void setTableHeader(JTableHeader tableHeader) {
        if (this.tableHeader != null) {
            this.tableHeader.removeMouseListener(mouseListener);
            TableCellRenderer defaultRenderer = this.tableHeader.getDefaultRenderer();
            if (defaultRenderer instanceof SortableHeaderRenderer) {
                this.tableHeader.setDefaultRenderer(((SortableHeaderRenderer) defaultRenderer).tableCellRenderer);
        this.tableHeader = tableHeader;
        if (this.tableHeader != null) {
            this.tableHeader.addMouseListener(mouseListener);
            this.tableHeader.setDefaultRenderer(
                    new SortableHeaderRenderer(this.tableHeader.getDefaultRenderer()));
    public boolean isSorting() {
        return sortingColumns.size() != 0;
    private Directive getDirective(int column) {
        for (int i = 0; i < sortingColumns.size(); i++) {
            Directive directive = (Directive)sortingColumns.get(i);
            if (directive.column == column) {
                return directive;
        return EMPTY_DIRECTIVE;
    public int getSortingStatus(int column) {
        return getDirective(column).direction;
    private void sortingStatusChanged() {
        clearSortingState();
        fireTableDataChanged();
        if (tableHeader != null) {
            tableHeader.repaint();
    public void setSortingStatus(int column, int status) {
        Directive directive = getDirective(column);
        if (directive != EMPTY_DIRECTIVE) {
            sortingColumns.remove(directive);
        if (status != NOT_SORTED) {
            sortingColumns.add(new Directive(column, status));
        sortingStatusChanged();
    protected Icon getHeaderRendererIcon(int column, int size) {
        Directive directive = getDirective(column);
        if (directive == EMPTY_DIRECTIVE) {
            return null;
        return new Arrow(directive.direction == DESCENDING, size, sortingColumns.indexOf(directive));
    private void cancelSorting() {
        sortingColumns.clear();
        sortingStatusChanged();
    public void setColumnComparator(Class type, Comparator comparator) {
        if (comparator == null) {
            columnComparators.remove(type);
        } else {
            columnComparators.put(type, comparator);
    protected Comparator getComparator(int column) {
        Class columnType = tableModel.getColumnClass(column);
        Comparator comparator = (Comparator) columnComparators.get(columnType);
        if (comparator != null) {
            return comparator;
        if (Comparable.class.isAssignableFrom(columnType)) {
            return COMPARABLE_COMAPRATOR;
        return LEXICAL_COMPARATOR;
    private Row[] getViewToModel() {
        if (viewToModel == null) {
            int tableModelRowCount = tableModel.getRowCount();
            viewToModel = new Row[tableModelRowCount];
            for (int row = 0; row < tableModelRowCount; row++) {
                viewToModel[row] = new Row(row);
            if (isSorting()) {
                Arrays.sort(viewToModel);
        return viewToModel;
    public int modelIndex(int viewIndex)
        return getViewToModel()[viewIndex].modelIndex;
    private int[] getModelToView()
        if (modelToView == null) {
            int n = getViewToModel().length;
            modelToView = new int[n];
            for (int i = 0; i < n; i++) {
                modelToView[modelIndex(i)] = i;
        return modelToView;
    // TableModel interface methods
    public int getRowCount() {
        return (tableModel == null) ? 0 : tableModel.getRowCount();
    public int getColumnCount() {
        return (tableModel == null) ? 0 : tableModel.getColumnCount();
    public String getColumnName(int column) {
        return tableModel.getColumnName(column);
    public Class getColumnClass(int column) {
        return tableModel.getColumnClass(column);
    public boolean isCellEditable(int row, int column) {
        return tableModel.isCellEditable(modelIndex(row), column);
    public Object getValueAt(int row, int column) {
        return tableModel.getValueAt(modelIndex(row), column);
    public void setValueAt(Object aValue, int row, int column) {
        tableModel.setValueAt(aValue, modelIndex(row), column);
    // Helper classes
    private class Row implements Comparable {
        private int modelIndex;
        public Row(int index) {
            this.modelIndex = index;
        public int compareTo(Object o) {
            int row1 = modelIndex;
            int row2 = ((Row) o).modelIndex;
            for (Iterator it = sortingColumns.iterator(); it.hasNext();) {
                Directive directive = (Directive) it.next();
                int column = directive.column;
                Object o1 = tableModel.getValueAt(row1, column);
                Object o2 = tableModel.getValueAt(row2, column);
                int comparison = 0;
                // Define null less than everything, except null.
                if (o1 == null && o2 == null) {
                    comparison = 0;
                } else if (o1 == null) {
                    comparison = -1;
                } else if (o2 == null) {
                    comparison = 1;
                } else {
                    comparison = getComparator(column).compare(o1, o2);
                if (comparison != 0) {
                    return directive.direction == DESCENDING ? -comparison : comparison;
            return 0;
    private class TableModelHandler implements TableModelListener {
        public void tableChanged(TableModelEvent e) {
            // If we're not sorting by anything, just pass the event along.            
            if (!isSorting()) {
                clearSortingState();
                fireTableChanged(e);
                return;
            // If the table structure has changed, cancel the sorting; the            
            // sorting columns may have been either moved or deleted from            
            // the model.
            if (e.getFirstRow() == TableModelEvent.HEADER_ROW) {
                cancelSorting();
                fireTableChanged(e);
                return;
            // We can map a cell event through to the view without widening            
            // when the following conditions apply:
            // a) all the changes are on one row (e.getFirstRow() == e.getLastRow()) and,
            // b) all the changes are in one column (column != TableModelEvent.ALL_COLUMNS) and,
            // c) we are not sorting on that column (getSortingStatus(column) == NOT_SORTED) and,
            // d) a reverse lookup will not trigger a sort (modelToView != null)
            // Note: INSERT and DELETE events fail this test as they have column == ALL_COLUMNS.
            // The last check, for (modelToView != null) is to see if modelToView
            // is already allocated. If we don't do this check; sorting can become
            // a performance bottleneck for applications where cells 
            // change rapidly in different parts of the table. If cells
            // change alternately in the sorting column and then outside of            
            // it this class can end up re-sorting on alternate cell updates -
            // which can be a performance problem for large tables. The last
            // clause avoids this problem.
            int column = e.getColumn();
            if (e.getFirstRow() == e.getLastRow()
                    && column != TableModelEvent.ALL_COLUMNS
                    && getSortingStatus(column) == NOT_SORTED
                    && modelToView != null) {
                int viewIndex = getModelToView()[e.getFirstRow()];
                fireTableChanged(new TableModelEvent(TableSorter.this,
                                                     viewIndex, viewIndex,
                                                     column, e.getType()));
                return;
            // Something has happened to the data that may have invalidated the row order.
            clearSortingState();
            fireTableDataChanged();
            return;
    private class MouseHandler extends MouseAdapter {
        public void mouseClicked(MouseEvent e) {
            JTableHeader h = (JTableHeader) e.getSource();
            TableColumnModel columnModel = h.getColumnModel();
            int viewColumn = columnModel.getColumnIndexAtX(e.getX());
            int column = columnModel.getColumn(viewColumn).getModelIndex();
            if (column != -1) {
                int status = getSortingStatus(column);
                if (!e.isControlDown()) {
                    cancelSorting();
                // Cycle the sorting states through {NOT_SORTED, ASCENDING, DESCENDING} or
                // {NOT_SORTED, DESCENDING, ASCENDING} depending on whether shift is pressed.
                status = status + (e.isShiftDown() ? -1 : 1);
                status = (status + 4) % 3 - 1; // signed mod, returning {-1, 0, 1}
                setSortingStatus(column, status);
    private static class Arrow implements Icon {
        private boolean descending;
        private int size;
        private int priority;
        public Arrow(boolean descending, int size, int priority) {
            this.descending = descending;
            this.size = size;
            this.priority = priority;
        public void paintIcon(Component c, Graphics g, int x, int y) {
            Color color = c == null ? Color.GRAY : c.getBackground();            
            // In a compound sort, make each succesive triangle 20%
            // smaller than the previous one.
            int dx = (int)(size/2*Math.pow(0.8, priority));
            int dy = descending ? dx : -dx;
            // Align icon (roughly) with font baseline.
            y = y + 5*size/6 + (descending ? -dy : 0);
            int shift = descending ? 1 : -1;
            g.translate(x, y);
            // Right diagonal.
            g.setColor(color.darker());
            g.drawLine(dx / 2, dy, 0, 0);
            g.drawLine(dx / 2, dy + shift, 0, shift);
            // Left diagonal.
            g.setColor(color.brighter());
            g.drawLine(dx / 2, dy, dx, 0);
            g.drawLine(dx / 2, dy + shift, dx, shift);
            // Horizontal line.
            if (descending) {
                g.setColor(color.darker().darker());
            } else {
                g.setColor(color.brighter().brighter());
            g.drawLine(dx, 0, 0, 0);
            g.setColor(color);
            g.translate(-x, -y);
        public int getIconWidth() {
            return size;
        public int getIconHeight() {
            return size;
    private class SortableHeaderRenderer implements TableCellRenderer {
        private TableCellRenderer tableCellRenderer;
        public SortableHeaderRenderer(TableCellRenderer tableCellRenderer) {
            this.tableCellRenderer = tableCellRenderer;
        public Component getTableCellRendererComponent(JTable table,
                                                       Object value,
                                                       boolean isSelected,
                                                       boolean hasFocus,
                                                       int row,
                                                       int column) {
            Component c = tableCellRenderer.getTableCellRendererComponent(table,
                    value, isSelected, hasFocus, row, column);
            if (c instanceof JLabel) {
                JLabel l = (JLabel) c;
                l.setHorizontalTextPosition(JLabel.LEFT);
                int modelColumn = table.convertColumnIndexToModel(column);
                l.setIcon(getHeaderRendererIcon(modelColumn, l.getFont().getSize()));
            return c;
    private static class Directive {
        private int column;
        private int direction;
        public Directive(int column, int direction) {
            this.column = column;
            this.direction = direction;
}

Answer 1

The table listens to the TableModel for changes. Changing the table by adding/removing
rows or columns has no affect on its table model. If you make changes to the table model
the table will be notified by its TableModelListener and change its view. So tell
MyTableModel about the change of data:
public class TableSorterDemo implements ActionListener
    MyTableModel tableModel;
    public TableSorterDemo()
        defaultListModel = new DefaultListModel();
        init1();
        tableModel = new MyTableModel(defaultListModel);
        TableSorter sorter = new TableSorter(tableModel);
    public void actionPerformed(ActionEvent ae)
        if (ae.getSource()==clickMe)
            defaultListModel.removeAllElements();
            init2();
            tableModel.fireTableStructureChanged();
}