listselectiondemo.java

《java事件处理指南》一书的代码,好东西

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

public class ListSelectionDemo extends JFrame 
                             implements ListSelectionListener
{
   private JTextField jtf;
   private JList list;
   private DefaultListModel model;

   public ListSelectionDemo() 
   {
/*  A JList object is created by first initializing a DefaultListModel  */
/*  with a list of names.  The JList object registers a                 */
/*  ListDataListener.  The ListSelectionDemo class serves as the        */
/*  ListDataListener, so the addListSelectionListener() method is       */
/*  passed the "this" reference as an argument.                         */

      model = new DefaultListModel();
      model.addElement("Lisa");
      model.addElement("Angela");
      model.addElement("Diana");

      list = new JList(model);
      list.setVisibleRowCount(5);
      list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
      list.addListSelectionListener(this);

      jtf = new JTextField(15);
      jtf.setEditable(false);

      JPanel centerPanel = new JPanel();
      centerPanel.add(new JScrollPane(list));

      JPanel southPanel = new JPanel();
      southPanel.add(jtf);

      getContentPane().add(centerPanel, BorderLayout.CENTER);
      getContentPane().add(southPanel, BorderLayout.SOUTH);

      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      setBounds(100, 100, 300, 250);
      setVisible(true);
   }

/*  The ListSelectionDemo class serves as the ListSelectionListener  */
/*  so it implements the valueChanged() method.  When the user       */
/*  changes the list selection, a ListSelectionEvent is generated    */
/*  and sent to this method.  The method displays the currently      */
/*  selected item in a textfield at the bottom of the frame.         */

   public void valueChanged(ListSelectionEvent event)
   {
      jtf.setText("Selection is "+
            (String)model.elementAt(list.getSelectedIndex()));
   }

   public static void main(String args[]) 
   {
      ListSelectionDemo demo = new ListSelectionDemo();
   }
}