// Figure 8.47import java.awt.*;import java.awt.event.ActionEvent;public class FahrenheitField extends EventTextField {	private Driver driver;	/**	pre:	d != null  <br>	 *		post:	driver == d	 *				and  getX() == x  and  getY() == y	 *				and	getWidth() = 60  and  getHeight() ==30  	 */	public FahrenheitField(int x, int y, Driver d)  {		super();    	setBounds(x, y, 100, 30);		driver = d;	}	/**	pre:	driver != null  <br>	 *		post:	the postconditon of driver.updateCelsius() 	 */	public void actionPerformed( ActionEvent e )   {		driver.updateCelsius();		driver.updateFahrenSlider();	}}