Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: javax.swing.JTable - swing

Question

I have a code which when run generates a table in swing form which contains a set of checkboxes which can be selected or unselected
When I click on the Check All tab I am able to select/unselect all the other below check boxes but when i select one of the below checkboxes individually I get this error :
> Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: javax.swing.JTable
at com.tps.charts.CheckBoxHeader.handleClickEvent(JTableHeaderCheckBox.java:152)
at com.tps.charts.CheckBoxHeader.mouseClicked(JTableHeaderCheckBox.java:168)
at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source)
at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source)
at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source)
at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source)
at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source) mousePressed......
at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source)
at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source)
at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source)
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.pumpOneEventForHierarchy(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)
The code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;
public class JTableHeaderCheckBox {
private Object colNames[] = {"", "String", "String"};
private Object[][] data = {};
private DefaultTableModel dtm;
private JTable table;
private TableColumn tc;
public void buildGUI() {
dtm = new DefaultTableModel(data, colNames);
table = new JTable(dtm);
for (int x = 0; x < 5; x++) {
dtm.addRow(new Object[]{false, "Row " + (x + 1) + " Col 2", "Row " + (x + 1) + " Col 3"});
}
JScrollPane sp = new JScrollPane(table);
tc = table.getColumnModel().getColumn(0);
tc.setCellEditor(table.getDefaultEditor(Boolean.class));
tc.setCellRenderer(table.getDefaultRenderer(Boolean.class));
tc.setHeaderRenderer(new CheckBoxHeader(new MyItemListener()));
JFrame f = new JFrame();
f.getContentPane().add(sp);
f.pack();
f.setLocationRelativeTo(null);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
private class MyItemListener implements ItemListener {
#Override
public void itemStateChanged(ItemEvent e) {
System.out.println("ItemStateChanged");
Object source = e.getSource();
if (source instanceof AbstractButton == false) {
return;
}
boolean checked = e.getStateChange() == ItemEvent.SELECTED;
for (int x = 0, y = table.getRowCount(); x < y; x++) {
table.setValueAt(checked, x, 0);
}
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new JTableHeaderCheckBox().buildGUI();
}
});
}
}
class CheckBoxHeader extends JCheckBox implements TableCellRenderer, MouseListener {
private static final long serialVersionUID = 1L;
private CheckBoxHeader rendererComponent;
private int column;
private boolean mousePressed = false;
public CheckBoxHeader(ItemListener itemListener) {
rendererComponent = this;
rendererComponent.addItemListener(itemListener);
}
#Override
public Component getTableCellRendererComponent(JTable table, Object value,
boolean isSelected, boolean hasFocus, int row, int column) {
if (table != null) {
JTableHeader header = table.getTableHeader();
table.addMouseListener(rendererComponent);
if (header != null) {
rendererComponent.setForeground(header.getForeground());
rendererComponent.setBackground(header.getBackground());
rendererComponent.setFont(header.getFont());
header.addMouseListener(rendererComponent);
}
}
setColumn(column);
rendererComponent.setText("Check All");
setBorder(UIManager.getBorder("TableHeader.cellBorder"));
return rendererComponent;
}
protected void setColumn(int column) {
this.column = column;
}
public int getColumn() {
return column;
}
protected void handleClickEvent(MouseEvent e) {
if (mousePressed) {
mousePressed = false;
JTableHeader header = (JTableHeader) (e.getSource());
JTable tableView = header.getTable();
TableColumnModel columnModel = tableView.getColumnModel();
int viewColumn = columnModel.getColumnIndexAtX(e.getX());
column = tableView.convertColumnIndexToModel(viewColumn);
if (viewColumn == this.column && e.getClickCount() == 1 && column != -1) {
System.out.println(" doClick()......");
doClick();
}
}
}
#Override
public void mouseClicked(MouseEvent e) {
System.out.println(" mouseClicked()......");
handleClickEvent(e);
/* problem occurs from this line */
((JTableHeader) e.getSource()).repaint();
}
#Override
public void mousePressed(MouseEvent e) {
//System.out.println("mousePressed(MouseEvent e).......");
mousePressed = true;
}
#Override
public void mouseReleased(MouseEvent e) {
//System.out.println(" mouseReleased()......");
}
#Override
public void mouseEntered(MouseEvent e) {
//System.out.println(" mouseEntered()......");
}
#Override
public void mouseExited(MouseEvent e) {
//System.out.println("mouseExited()......");
}
}
with Exception
Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException:
javax.swing.JTable cannot be cast to javax.swing.table.JTableHeader

Answer 1

On line 152: JTableHeader header = (JTableHeader)(e.getSource()); you are assuming the event is on the table header. You need to check event source's class to see if it's on the header or an individual checkbox.

Answer 2

You are casting the source of the event to a JTableHeader:
JTableHeader header = (JTableHeader) (e.getSource());
and the source is a JTable when you click at a cell. I would have two different listeners for the header and the cell selection or you can do a hack by checking event.getSource() instanceof ... in your mouse-click-listener.