其中一个类：
import javax.swing.*;
import java.PushCounterPanel;
 
public class PushCounter
{
 public static void main(String []args)
 {
  JFrame frame=new JFrame("Push Counter");
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  
  frame.getContentPane().add(new PushCounterPanel());
  frame.pack();
  frame.setVisible(true);
 }
}
 
 
另一个类：
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class PushCounterPanel extends JPanel;
{
 private int count;
 private JButton push;
 private JLabel label;
 
 public PushCounterPanel()
 {
  count=0;
  
  push=new JButton ("Push me");
  push.addActionListener(new ButtonListener());
  
  label=new JLabel ("Pushes:"+count);
  
  add(push);
  add(label);
  
  setPreferredSize(new Dimension (300,40));
  setBackground(Color.cyan);
 }
 private class ButtonListener implements ActionListener
 {
  public void actionPerformed(ActionListener event)
  {
   count++;
   label.setText("Pushes:"+count);
  }
 }
}

导包！

引入包，调用时在上面这么写 : import 包名.*; 或者；import 包名.类名;