Program import javax.swing.*; public class SwingThread extends JFrame { public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { @Override public void run() { final JFrame f = new JFrame("Swing using Thread Frame 1"); f.setSize(600, 400); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.setVisible(true); final JFrame fr = new JFrame("Swing using Thread Frame 2"); fr.setSize(600, 600); fr.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); fr.setVisible(true); } }); } } Output: