This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
did you try and read the API doc of the window (perhaps its JFrame or so) ? there is probably something like getDimension(), getWidth()/getHeight(), getSize(). and if you find the size... your halfway there :-) API Docs