import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
  
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextArea;
  
class MyFrame extends JFrame {
    JButton myButton;
    JTextArea myTextArea;
    int count;
    public MyFrame(String title) {
        super(title);
        myButton = new JButton("click me");
        myTextArea = new JTextArea();
        add(myButton);
        add(myTextArea);
        ButtonListener bList = new ButtonListener();
        myButton.addActionListener(bList);
    }
    class ButtonListener implements ActionListener //这里定义了一个内部类
    {
        public void actionPerformed(ActionEvent e) {
            count++;
            myTextArea.setText("button clicked" + count + "times");
        }
    }  
    // end of innerclass ButtonListener
    public static void main(String args[]) {
        MyFrame f = new MyFrame("Inner Class Frame");
        f.setSize(300, 300);
        f.setVisible(true);
        f.show();
    }
}

//源代码片段来自云代码http://yuncode.net