In JTable there is method:
public String getToolTipText(MouseEvent event) {
...
}
which uses tooltip from your renderer component. You can implement getToolTipText for your renderer component:
public String getToolTipText(MouseEvent event) {
//your implementation goes here
}
If you use DefaultTableCellRenderer you can just set the tooltip directly in the method getTableCellRendererComponent:
public Component getTableCellRendererComponent(JTable table, Object value,
boolean isSelected, boolean hasFocus, int row, int column) {
setToolTipText("<html>Tooltip at <b>cell</b> " + row + ", " + column + "</html>");
return super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
}
In order tooltip to be rendered as html you should include <html> in the beginning and </html> at the end of tooltip but you can use only very limited features of HTML in the tooltip.