Pass information from one JPanel to another

Hi,
Im trying to pass a varaible from one JPanel to another in order to move the animation by a certain amount of distance but for some reason the animation does not update any help would be most apprciated.

package systemRuntime;

import formulaSystem.Formula;
import javax.swing.*;

import diagramSystem.Diagram;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class SystemRuntime extends JFrame
{

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	private Formula formula;
	private Diagram diagram;
	
	private JPanel formulaPanel;
	private JPanel diagramPanel;
	
	public SystemRuntime() 
	{
		// TODO Auto-generated constructor stub
		super();
		setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
		
		formula = new Formula();
		diagram = new Diagram();
		
		formulaPanel = formula;
		diagramPanel = diagram;
		
		add( formulaPanel, BorderLayout.NORTH );
		add( diagramPanel );
		
		setSize( 500, 500 );
		setVisible( true );
	}
	
	/**
	 * @param args
	 */
	public static void main(String[] args) 
	{
		// TODO Auto-generated method stub
		new SystemRuntime();
	}	
}

package formulaSystem;

import javax.swing.*;
import java.awt.event.*;

public class Formula extends JPanel implements ActionListener
{

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
		
		
	private JTextField initialDisplacement;
	private JTextField finalDisplacement;	 
	private JButton generate;
	
	private int disp;
	
	public Formula()
	{
		// TODO Auto-generated constructor stub
		super();
				
		initialDisplacement = new JTextField( "0", 2 );
		finalDisplacement = new JTextField( "0", 2 );
		
		generate = new JButton( "Generate" );		
		generate.addActionListener( this );
		
		add( initialDisplacement );
		add( finalDisplacement );
		add( generate );
		
	}
	
	public void setter( int s )
	{
		disp = s;
	}
		
	public int getter()
	{
		return disp;
	}
	
	@Override
	public void actionPerformed( ActionEvent e ) 
	{
		// TODO Auto-generated method stub
		Object obj = e.getSource();
		if( obj.equals( generate ) )
		{
			setter( 80 );
			System.out.println( "True" );
		}
		repaint();
				
	}

}

package diagramSystem;

import javax.swing.*;
import formulaSystem.Formula;
import java.awt.*;


public class Diagram extends JPanel 
{

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	private Formula formula;
			
	public Diagram() 
	{
		// TODO Auto-generated constructor stub
		super();
		formula = new Formula();
	}
	
	
	@Override
	public void paintComponent( Graphics g )
	{
		super.paintComponent( g );
		g.setColor( Color.WHITE );
		g.fillRect( 0, 0, getWidth(), getHeight() );		
		g.setColor( Color.RED );
		g.fillOval( formula.getter(), 40, 50, 50 );	
				
	}	

}