import java.awt.Toolkit; import javax.swing.JFrame; public class Test2 extends JFrame{ public static void main(String[] args) { JFrame jf=new JFrame(); int windowsWedth = 600; int windowsHeight = 600; int width = Toolkit.getDefaultToolkit().getScreenSize().width; int height = Toolkit.getDefaultToolkit().getScreenSize().height; jf.setBounds((width - windowsWedth) / 2,(height - windowsHeight) / 2, windowsWedth, windowsHeight); jf.setVisible(true); } }