Java API

http://www.javabeginner.com/java-swing/java-jframe-class-example

Centering JFrame’s

By default,a Jframe is displayed in
the upper-left corner of the screen.
To display a frame at a specified
location,you can use the
setLocation(x,y) method in the JFrame
class. This method places the
upper-left corner of a frame at
location (x,y).

右上角的伪代码看起来像这样：

yourJFrame.setLocation(
  GraphicsEnvironment.getMaximumWindowBounds().getWidth() - 
  yourJFrame.getWidth(),0);