You can use your own cell renderer and then set the cell renderer tooltip
with the value of the cell.
something like this:

package Learn;

import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.JTable;
import java.awt.Component;

public class MyRenderer extends DefaultTableCellRenderer
{
 public MyRenderer()
 {
 }

 public Component getTableCellRendererComponent(JTable table,
                                              Object value,
                                              boolean isSelected,
                                              boolean hasFocus,
                                              int row,
                                              int column)
 {
   return this.setToolTipText(value.toString());
 }
}

and then you can set it as your own cell render in each column.

   Hope it helps you

       Amit Brabbing