JAVA13 - プログラム倉庫

import java.awt.*;
import java.awt.event.*;

public class ex28
{
  public static void main(String[] args)
  {
FrameListener f = new FrameListener("ex28");  
    Button b1 = new Button("計算せよ");
    f.add(b1);                        
    b1.addActionListener(f);          
    f.setVisible(true);                    
  }
}
class FrameListener extends Frame implements ActionListener
{
  public FrameListener(String title)
  {
    setTitle(title);
    setSize(500, 500);                  
    setBackground(Color.BLUE);          
    setLayout(new FlowLayout());    
    addWindowListener(new WindowAdapter()
      {
        public void windowClosing(WindowEvent e)
        {
          System.exit(0);                  
        }
      });
  }
  public void actionPerformed(ActionEvent e)
  {
    if (getBackground() != Color.RED)
      setBackground(Color.RED);        
    else
      setBackground(Color.BLUE);      
  }
}