By default, instances of Window subclasses such as Frame and Dialog appear at the upper-left corner of the screen when made visible. For a more user-friendly interface, you can center the component with only a few lines of code:

 	//  Create an instance of a Frame subclass	Frame f = new MyAppFrame();	//  Get default toolkit for system	Toolkit tk = Toolkit.getDefaultToolkit();	//  Obtain screen dimensions	Dimension screenSize = tk.getScreenSize();	//  Center the Frame instance by setting left and top edges	f.setLocation((screenSize.width -  f.getSize().width) / 2,			(screenSize.height - f.getSize().height) / 2);