Basically, when JAWS is requesting information from JTable.AccessibleJTable, getAccessibleChild(int) asks for the renderer's component and always pass null for the value. This request should never be called.

Steps to reproduce:
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1. Run JAWS 5.00.844 with Access Bridge 1.2GA
2. Run the following application
3. Click on a check box

Source Code:
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import java.awt.Component;

import javax.swing.BorderFactory;
import javax.swing.DefaultCellEditor;
import javax.swing.JCheckBox;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.UIManager;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableCellEditor;
import javax.swing.table.TableCellRenderer;
import javax.swing.table.TableModel;

final class JTableAccessibilityBug
{
private JFrame frame;

public static void main(String[] args)
{
JTableAccessibilityBug bug = new JTableAccessibilityBug();
bug.start();
}

private TableCellEditor buildBooleanEditor()
{
return new DefaultCellEditor(new JCheckBox());
}

private TableCellRenderer buildBooleanRenderer()
{
return new TableCellRenderer()
{
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column)
{
JCheckBox checkBox = new JCheckBox();
checkBox.setSelected(((Boolean) value).booleanValue());
return checkBox;
}
};
}

private JComponent buildContentPane()
{
JTable table = new JTable(buildTableModel());
table.getAccessibleContext();
table.setDefaultRenderer(Boolean.class, buildBooleanRenderer());
table.setDefaultEditor(Boolean.class, buildBooleanEditor());
return new JScrollPane(table);
}

private TableModel buildTableModel()
{
Object[] columnNames = { "Key", "Value" };

final Object[][] data =
{
{ "Key1", Boolean.TRUE },
{ "Key2", Boolean.FALSE },
{ "Key3", Boolean.TRUE },
{ "Key4", Boolean.FALSE },
};

return new DefaultTableModel(data, columnNames)
{
public boolean isCellEditable(int rowIndex, int columnIndex)
{
return (columnIndex == 1);
}

public Class getColumnClass(int columnIndex)
{
switch (columnIndex)
{
case 0:
return String.class;
case 1:
return Boolean.class;
default:
return super.getColumnClass(columnIndex);
}
}
};
}

private void start()
{
try
{
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
}
catch (Exception e) {}

frame = new JFrame("Test JTable Accessibility");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(buildContentPane());
((JComponent) frame.getContentPane()).setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
frame.setSize(500, 300);
frame.setLocation(100, 100);
frame.setVisible(true);
}
}


Trace Output:
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java.lang.NullPointerException
at JTableAccessibilityBug$1.getTableCellRendererComponent(JTableAccessibilityBug.java:38)
at javax.swing.JTable$AccessibleJTable.getAccessibleChild(JTable.java:4457)
at javax.swing.JTable$AccessibleJTable.getAccessibleAt(JTable.java:4838)
at javax.swing.JTable$AccessibleJTable.valueChanged(JTable.java:4359)
at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:187)
at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:167)
at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:214)
at javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:402)
at javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:411)
at javax.swing.DefaultListSelectionModel.setSelectionInterval(DefaultListSelectionModel.java:435)
at javax.swing.JTable.changeSelectionModel(JTable.java:1505)
at javax.swing.JTable.changeSelection(JTable.java:1548)
at javax.swing.plaf.basic.BasicTableUI$MouseInputHandler.adjustFocusAndSelection(BasicTableUI.java:522)
at javax.swing.plaf.basic.BasicTableUI$MouseInputHandler.mousePressed(BasicTableUI.java:494)
at java.awt.AWTEventMulticaster.mousePressed(AWTEventMulticaster.java:222)
at java.awt.Component.processMouseEvent(Component.java:5097)
at java.awt.Component.processEvent(Component.java:4897)
at java.awt.Container.processEvent(Container.java:1569)
at java.awt.Component.dispatchEventImpl(Component.java:3615)
at java.awt.Container.dispatchEventImpl(Container.java:1627)
at java.awt.Component.dispatchEvent(Component.java:3477)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:3483)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3195)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3128)
at java.awt.Container.dispatchEventImpl(Container.java:1613)
at java.awt.Window.dispatchEventImpl(Window.java:1606)
at java.awt.Component.dispatchEvent(Component.java:3477)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:456)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:145)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:137)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:100)
###@###.### 2004-11-06 00:00:44 GMT