example5_6.java

书中的例题

    /*  下拉列表示例   */
	import java.awt.*; 
    import java.awt.event.*; 
    import javax.swing.*; 
    class CobDemo extends JFrame implements ItemListener
	{ 
      JLabel jlb; 
      ImageIcon france, germany, italy, japan; 
      CobDemo()
		{ 
         super("下拉列表示例");
	     setSize(300,200);setVisible(true);
       Container contentPane = getContentPane(); 
       contentPane.setLayout(new FlowLayout()); 
       JComboBox jc = new JComboBox(); 
       jc.addItem("中国"); 
       jc.addItem("俄罗斯"); 
       jc.addItem("韩国"); 
       jc.addItem("联合国"); 
       jc.addItemListener(this); 
       contentPane.add(jc); 
       jlb = new JLabel(new ImageIcon("中国.jpg")); 
       contentPane.add(jlb); 
       validate();
       addWindowListener(new WindowAdapter()
         {public void windowClosing(WindowEvent e)
           {System.exit(0);}});
    } 
    public void itemStateChanged(ItemEvent ie)
	{ 
       String s = (String)ie.getItem().toString(); 
       jlb.setIcon(new ImageIcon(s + ".jpg")); 
    } 
  } 
  public class Example5_6
  {  public static void main(String args[])
       {  new CobDemo();   }
  }