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

/** Marquee lights program  (Figure 12.7)
 *  Author: David D. Riley
 *  Date:   January, 2005
 */
public class Driver implements ActionListener{
	private	Oval[] dots;
	private	JFrame window;
	
	/** post:	window is created 
	 *			and a row of filled ovals is assigned to dots
	 *				(These ovals span the window horizontally.)
	 *			and any dot with a multiple of 3 for an index
	 *				is dark gray, while all other dots are white.  
	 */
	public Driver()  { 
		window = new JFrame("Marquee Lights");
		window.setBounds(10, 10, 600, 500);
		window.setVisible(true);
		window.setLayout(null);
		window.setBackground(Color.black);
			JButton button = new JButton("Click to change light colors.");
			button.setBounds(100, 420, 400, 30);
			button.addActionListener(this);
			window.add(button, 0);
 
		int xPos = 5;
		dots = new Oval[32];
		for  ( int j=0; j!=32; j++ )   {
			dots[j] = new Oval(xPos, 100, 10, 10);
			if ( j % 3 == 0 )   {
				dots[j].setBackground( Color.darkGray );
			} else {
				dots[j].setBackground( Color.white );
			}
			window.add(dots[j], 0);
			xPos = xPos + 15;
		}
		window.repaint();
	}
	
	/**	post:	all dot's old colors are moved to the left by one dot
	 *			and the rightmost dot gets the previous color of 
	 *			the leftmost dot 
	 */
	public void actionPerformed(ActionEvent e)   {
		Color leftmostDotColor;
		leftmostDotColor = dots[0].getBackground();
		for  ( int j=0; j!=31; j++ )   {
			dots[j].setBackground( dots[j+1].getBackground() );
		}
		dots[31].setBackground( leftmostDotColor );
		window.repaint();
	}
}