FULL PRODUCT VERSION :
java version "1.6.0_20"
Java(TM) SE Runtime Environment (build 1.6.0_20-b02)
Java HotSpot(TM) Client VM (build 16.3-b01, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Windows 7 Professional

A DESCRIPTION OF THE PROBLEM :
When the DefaultTableModel of a sortable JTable is cleared by means of a
tblModel.setRowCount(0);
the sorter gets fired, which leads to an
java.lang.ArrayIndexOutOfBoundsException: 0 >= 0

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the example code, click on any column's header, then press [Update]

Note: As long as you do NOT press a header, the code works fine.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
No ArrayIndexOutOfBounds (or any other) Exception
ACTUAL -
ArrayIndexOutOfBoundsException: 0 >= 0

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException:
 0 >= 0
        at java.util.Vector.elementAt(Unknown Source)
        at javax.swing.table.DefaultTableModel.getValueAt(Unknown Source)
        at UpdateSortableTable$1.getColumnClass(UpdateSortableTable.java:52)
        at javax.swing.table.TableRowSorter.useToString(Unknown Source)
        at javax.swing.DefaultRowSorter.updateUseToString(Unknown Source)
        at javax.swing.DefaultRowSorter.sort(Unknown Source)
        at javax.swing.DefaultRowSorter.shouldOptimizeChange(Unknown Source)
        at javax.swing.DefaultRowSorter.rowsDeleted(Unknown Source)
        at javax.swing.JTable.notifySorter(Unknown Source)
        at javax.swing.JTable.sortedTableChanged(Unknown Source)
        at javax.swing.JTable.tableChanged(Unknown Source)
        at javax.swing.table.AbstractTableModel.fireTableChanged(Unknown Source)

        at javax.swing.table.AbstractTableModel.fireTableRowsDeleted(Unknown Sou
rce)
        at javax.swing.table.DefaultTableModel.setNumRows(Unknown Source)
        at javax.swing.table.DefaultTableModel.setRowCount(Unknown Source)
        at UpdateSortableTable$2.actionPerformed(UpdateSortableTable.java:79)
        at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
        at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
        at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
        at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Sour
ce)
        at java.awt.Component.processMouseEvent(Unknown Source)
        at javax.swing.JComponent.processMouseEvent(Unknown Source)
        at java.awt.Component.processEvent(Unknown Source)
        at java.awt.Container.processEvent(Unknown Source)
        at java.awt.Component.dispatchEventImpl(Unknown Source)
        at java.awt.Container.dispatchEventImpl(Unknown Source)
        at java.awt.Component.dispatchEvent(Unknown Source)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
        at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
        at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
        at java.awt.Container.dispatchEventImpl(Unknown Source)
        at java.awt.Window.dispatchEventImpl(Unknown Source)
        at java.awt.Component.dispatchEvent(Unknown Source)
        at java.awt.EventQueue.dispatchEvent(Unknown Source)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
        at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
        at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
        at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
        at java.awt.EventDispatchThread.run(Unknown Source)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;

public class UpdateSortableTable extends JFrame {
  final String HEADER[]= {"No.", "Item", "Price", "Count"};
  Object data[][]= {
{1, "Oak", 7.40, 1000},
{2, "Beech", 10.50, 500},
{3, "Cherry", 15.00, 150},
{4, "Pine", 5.0, 2000},
};
  DefaultTableModel tblModel;
  JTable table;


  public UpdateSortableTable() {
    super("UpdateSortableTable");
    setSize(315, 150);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Container contentPane = getContentPane();

    tblModel = new DefaultTableModel(data, HEADER) {
      public Class getColumnClass(int column) {
Class returnValue;
if (column>=0 && column<getColumnCount()) {
returnValue= getValueAt(0, column).getClass();
}
else {
returnValue= null;//Object.class;
}
return returnValue;
      }

// Make read-only
      public boolean isCellEditable(int x, int y) {
return false;
      }
    };
    table = new JTable(tblModel);
    table.setAutoCreateColumnsFromModel(false);
    table.setAutoCreateRowSorter(true);

    JScrollPane scrollPane = new JScrollPane (table);
    contentPane.add(scrollPane, BorderLayout.CENTER);
    JButton bUpdate= new JButton("Update");
    bUpdate.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent evt) {
data[0][1]= "Maple";
tblModel.setRowCount(0);
tblModel.addRow(data[0]);
tblModel.addRow(data[1]);
      }
    });
    contentPane.add(bUpdate, BorderLayout.SOUTH);
    setVisible(true);
  }

  public static void main(String args[]) {
    EventQueue.invokeLater(new Runnable() {
      public void run() {
new UpdateSortableTable();
      }
    });
  }

}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Either (1.)
{code}
/* The sorter obviously gets fired even if there are no rows. So check the
rowCount in
public Class getColumnClass(int column)
*/
if (getRowCount()>0) {
returnValue= getValueAt(0, column).getClass();
}
else {
returnValue= null;
}
return returnValue;
{/code}


or (2.)
Clear the tableModel in a loop
{code}
int j= tblModel.getRowCount();
for (int i=0; i<j; i++)
tblModel.removeRow(0);
{/code}