Interface of

• Window .dispose () // release (closed) window
• this.setResizeable (false); // screen size is not adjustable
• Jpanel or Jframe add keyboard listeners invalid:
  impossible to obtain because there is no keyboard monitor screen focus will need to monitor the controls to get the screen to focus, as follows:

控件名.setFocusable(true);  /*注意要写setVisible(true)后面才行。*/