example4_16.java

书中的例题

/* 演示下拉列表及列表 */
import java.awt.*;
import java.awt.event.*;
public class Example4_16 extends Frame implements
ItemListener,ActionListener
{
   Choice choice; 
   TextField text;
   List  list;
   Button add,del;
   private class WindowCloser extends WindowAdapter
     {  public void windowClosing(WindowEvent we)
	       {System.exit(0);}	    
     }
   Example4_16()
   {
	  super("演示下拉列表及列表");
	  setSize(200,200);
	  setVisible(true);
	  setLayout(new FlowLayout());  
	  choice=new Choice(); 
      text=new TextField(8);
	  list=new List(6,true);
      choice.add("产品展示"); 
      choice.add("人才天地");
      choice.add("企业名录");     
      choice.add("行业资讯");
      add=new Button("添加");
      del=new Button("删除");
      add(choice);  add(del); 
      add(text);    add(add);  
	  add(list);
	  validate();     
	  add.addActionListener(this);
	  del.addActionListener(this);
      choice.addItemListener(this);
      addWindowListener(new WindowCloser());
   }
   public void itemStateChanged(ItemEvent e)
   {  String name=choice.getSelectedItem();
      int index=choice.getSelectedIndex();
      list.add("\n"+index+":"+name);
   }
   public void actionPerformed(ActionEvent e)
   {  if(e.getSource()==add||e.getSource()==text)
        {  String name=text.getText();
           if(name.length()>0)
              {  choice.add(name);
                 choice.select(name);
                 list.add("\n添加"+name);
              }
        }
      else if(e.getSource()==del)
        {  choice.remove(choice.getSelectedIndex());
           list.add("\n删除"+choice.getSelectedItem());
        }
   }
 public static void main(String[] args) 
	{  new Example4_16();	}

}