Java tutorial
//package com.java2s; import javax.swing.*; import java.awt.*; public class Main { public static void createAndShowGUI(final String titile, final JPanel pane) { SwingUtilities.invokeLater(new Runnable() { public void run() { JFrame frame = new JFrame(titile); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); pane.setOpaque(true); frame.setContentPane(pane); frame.pack(); // frame.setSize(width, height); frame.setVisible(true); moveToCenter(frame); } }); } public static void moveToCenter(JFrame frame) { int windowWidth = frame.getWidth(); int windowHeight = frame.getHeight(); Toolkit kit = Toolkit.getDefaultToolkit(); Dimension screenSize = kit.getScreenSize(); int screenWidth = screenSize.width; int screenHeight = screenSize.height; frame.setLocation(screenWidth / 2 - windowWidth / 2, screenHeight / 2 - windowHeight / 2); } }