driver.java

Java程序设计(美) David D. Riley著 机械工业出版社 书籍配套 代码

import java.awt.Color;
import javax.swing.JFrame;

/**	Author: David D. Riley
 *		Date: Jan, 2005
 *   Three Squares Program (Figure 4.10)
 */
public class Driver  {
	private JFrame  theWindow;
	private Rectangle leftSquare, midSquare, rightSquare;

	/**	post:	a window with three blue filled squares is drawn  */
	public Driver()   {
		theWindow = new JFrame("The Window");
		theWindow.setBounds(10, 10, 450, 250);
		theWindow.setLayout(null);
		theWindow.setBackground(Color.white);
		theWindow.setVisible(true);
		leftSquare = new Rectangle(100, 100, 50, 50);
		colorAndAdd(leftSquare, Color.blue);
		midSquare = new Rectangle(200, 100, 50, 50);
		colorAndAdd(midSquare, Color.blue);
		rightSquare = new Rectangle(300, 100, 50, 50);
		colorAndAdd(rightSquare, Color.blue);
	}
	
	/**	pre:	w has been instantiated  
	 *			and r has been instantiated  
	 *			and c is a valid Color
	 *	post:	r is set to color c 
	 *			and  r is added to theWindow   
	 */
	private  void  colorAndAdd(Rectangle r, Color c)   {
        r.setBackground(c);
        theWindow.add(r, 0);
        r.repaint();
	}
}