...
        DefaultTableCellRenderer centerRenderer =  new  DefaultTableCellRenderer (),
                                  rightRenderer =  new  DefaultTableCellRenderer ();
        centerRenderer.setHorizontalAlignment (SwingConstants.CENTER);
        rightRenderer.setHorizontalAlignment  (SwingConstants.RIGHT);
        TableColumn column =  null ;
         for  ( int  i =  0 ; i <  6 ; i++) {
            column = myTable.getColumnModel ().getColumn (i);
             switch  (i) {
                 case   2 : column.setCellRenderer (centerRenderer);  break ;
                 case   3 : column.setCellRenderer (rightRenderer);   break ;
                default :   break ;
            }
        }
        ...