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

/** Random Line Program  (Figure 11.4)
 *  Author: David D. Riley
 *  Date: January, 2005
 */
public class Driver implements ActionListener {
   private JFrame  window;
	private JButton addBtn, redBtn;
	private Bag<RandomLine> bagOfLines;

	/**	post:	window is created at (10, 10) with width and height of 400
	 *			and  addBtn & removeBtn are added to window  
	 */
	public Driver()  {
		window = new JFrame("Random Lines");
		window.setBounds(10, 10, 400, 400);
		window.setVisible(true);
		window.setLayout(null);
		addBtn = new JButton("Add a Line");
		addBtn.setBounds(10, 330, 180, 30);
        addBtn.addActionListener(this);
		window.add( addBtn, 0 );
		redBtn = new JButton("Color Line Red");
		redBtn.setBounds(210, 330, 180, 30); 
        redBtn.addActionListener(this);
		window.add(redBtn, 0 );
		window.repaint();
		bagOfLines = new Bag<RandomLine>();
	}
    
	/**	post:	e.getSource() == addBtn  
	 *				implies  a new randomly drawn line segment appears.
	 *			and  e.getSource() == redBtn
	 *				implies one line from pane@pre has been removed 
	 */
	public  void  actionPerformed(ActionEvent e)   {
		RandomLine someLine;
		if (e.getSource() == addBtn)   {
			someLine = new RandomLine();
			window.getContentPane().add(someLine, 0);
			bagOfLines.add(someLine);
    	} else {
    		if (bagOfLines.size() != 0)   {
				someLine = bagOfLines.item();
				someLine.setBackground(Color.red);
			}
    	}
		window.repaint();
    }
}