Ho risolto , questa è una classe di prova....

codice:
import java.awt.EventQueue;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.text.DateFormat;
import java.text.SimpleDateFormat;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;

import com.toedter.calendar.JDateChooser;


public class Calendario extends JFrame {

	private JPanel contentPane;

	/**
	 * Launch the application.
	 */
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					Calendario frame = new Calendario();
					frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}

	/**
	 * Create the frame.
	 */
	public Calendario() {
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setBounds(100, 100, 450, 300);
		contentPane = new JPanel();
		contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
		setContentPane(contentPane);
		contentPane.setLayout(null);
		
		
		
		
		final JDateChooser dateChooser = new JDateChooser();
		dateChooser.setBounds(126, 72, 152, 19);
		contentPane.add(dateChooser);
		
		dateChooser.addPropertyChangeListener (new
				PropertyChangeListener () {
				    public void propertyChange (PropertyChangeEvent evt) {
				    	if (evt.getPropertyName().equals("date")) { 
				    	DateFormat dateformat1 = new SimpleDateFormat("yyyy/MM/dd");
				    	String data = dateformat1.format(dateChooser.getDate()); 	
				    	System.out.println(data);
				    	}
				    }
				});

	}
}
Perchè però mi obbliga a mettere final su JDateChooser?