Swing的JFrame窗体跳转及关闭问题

我通过窗体A 调用 窗体 B，点击窗体B右上角的x关闭窗体B，然后就退出整个程序了
请问怎么才能关闭B，但是保留A呢
A是用SwingUtilities.invokeLater执行的
A的调用代码：
  public static void main(String[] args) throws InvocationTargetException, InterruptedException{         SwingUtilities.invokeLater(new Runnable(){             public void run() {         JFrame.setDefaultLookAndFeelDecorated(true);           JDialog.setDefaultLookAndFeelDecorated(true);                    try {                      //设置皮肤                         UIManager.setLookAndFeel( new  SubstanceOfficeBlue2007LookAndFeel());                  } catch (UnsupportedLookAndFeelException e) {                     // TODO Auto-generated catch block                     e.printStackTrace();                 }                             ChatView cv = new ChatView();         name = "大肚腩";         cv.setTitle(name);         cv.setSize(500,400);   //      cv.setResizable(false);  //不允许用户改变窗口大小         cv.setDefaultCloseOperation(EXIT_ON_CLOSE); //       com.sun.awt.AWTUtilities.setWindowOpacity(cv, .7f);         cv.setVisible(true);         cv.setLocationRelativeTo(null);             }         });     }

不要使用 setDefaultCloseOperation(EXIT_ON_CLOSE)，使用 DISPOSE_ON_CLOSE