I have written an application which loads into a JTable a mysql database
table. Currently it gets the table name from the args[] array, and all
other parameters (host, database, mysql user and password) are fixed.

The main(String[] args) method is the standard Swing tutorial stuff
which run()s createAndShowGUI

createAndShowGUI is also a standard Swing tutorial wrapper which

       myGui = new myGui();
       myGui.setOpaque(true); //content panes must be opaque
       frame.setContentPane(myGui);
       //Display the window.
       frame.pack();
       frame.setVisible(true);  

myGui is currently an inner class that extends JPanel implements
ActionListener and make a GridBagLayout panel which currently contains :

 - a form of text areas, which echo the current value of host, user,
   database and table (all of which are so far disabled but the table
   name

 - a Commit button

 - the Jtable itself which is called as (c is a GridBagConstraints) :
 
        dbprova bottom = new dbprova(tabname);
        panel.add(bottom,c) ;

dbprova is a method in the top level class which

  super(new GridLayout(1,0));
  establishes the mysql connection
  issues the mysql select statement
  generates a new MyTableModel();    
  generates the JTable table = new JTable(mtm);  
  (wraps it in a scroll pane)
  adds the scroll pane and adjusts the table layout
  closes the mysql connection

The quoted Commit button in myGui is assciated to an action listener.
Its intended usage is that the user which might want to CHANGE the
database table (and in perspective database, user, host) enters it in
the appropriate form text area and presses Commit.

The action listener retrieves the table name and sets it into the global
variable tabname, but how can it force the Jtable to be reloaded ?

I thought perhaps one had to call revalidate, but it seems to do
nothing.

     public void actionPerformed(ActionEvent e) {
      if ("mysqlconnect".equals(e.getActionCommand())) {
           tabname=tabl.getText() ;
           System.out.println("now table is "+tabname );
           revalidate();
      }

How can one replace the "bottom" Jtable with a new instance and refresh
the display ?