firstwindow.java

《A first book of java》by Gary J.Bronson 北大出版社

import javax.swing.*;
public class FirstWindow extends JFrame
{
  private JFrame mainFrame;

  public FirstWindow() // a constructor
  {
    mainFrame = new JFrame("First GUI Window");

    mainFrame.setSize(300,150);
    mainFrame.show();
  } 

  public static void main(String args[])
  {
    new FirstWindow(); 
  }
}  // end of class