import java.awt.event.*;import javax.swing.Timer;/** EventTimer class (abstract) *  Author: David Riley *  Date: May, 2004  */public abstract class EventTimer extends Timer implements ActionListener  {    /** pre:    m > 0  <br>     *  post:   actionPerformed events are scheduled to occur every m milliseconds <br>     *  note:   a call to start is required to initiate the first event      */    public EventTimer(int m)  {    	super(m, null);        addActionListener( this );    }        /** EVENT HANDLER - called in response to each scheduled event	 *		(This method is designed to be overridden.)      */    public void actionPerformed( ActionEvent e )  {    }    	}