changeeventdemo.java

来自「《java事件处理指南》一书的代码,好东西」· Java 代码 · 共 61 行

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

public class ChangeEventDemo extends JFrame 
{
   private JSlider slider;
   private JTextField jtf;

   public ChangeEventDemo() 
   {

/*  A JSlider is created and placed on a JFrame.  The JSlider    */
/*  registers a ChangeListener.                                  */

      slider = new JSlider(JSlider.VERTICAL, 0, 50, 0);
      slider.setMajorTickSpacing(5);//主刻度间隔
      slider.setMinorTickSpacing(1);//附刻度间隔
      slider.setPaintTicks(true);
      slider.setPaintLabels(true);
      slider.setForeground(Color.black);
      slider.setBorder(BorderFactory.createLineBorder(Color.black));
      slider.addChangeListener(new ChangeHandler());

      jtf = new JTextField(15);
      jtf.setText("Value is "+slider.getValue());
      jtf.setEditable(false);

      JPanel p = new JPanel();
      p.add(slider);

      getContentPane().add(p, BorderLayout.CENTER);
      getContentPane().add(jtf, BorderLayout.SOUTH);

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

/*  The ChangeListener is implemented as an inner class.  Whenever  */
/*  the slider value is changed, a ChangeEvent is generated and     */
/*  sent to the stateChanged() method.  A JTextField at the bottom  */
/*  of the JFrame is updated to indicate the current value of the   */
/*  JSlider.                                                        */

   class ChangeHandler implements ChangeListener 
   {
      public void stateChanged(ChangeEvent event) 
      {
         JSlider js = (JSlider)event.getSource();
         jtf.setText("Value is "+js.getValue());
      }
   }

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