import javax.swing.*; public class Executor extends JFrame { public Executor(){ initUI(); } private void initUI(){ Panel panel = new Panel(); add(panel); pack(); setDefaultCloseOperation(EXIT_ON_CLOSE); setLocationRelativeTo(null); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { @Override public void run() { Executor executor = new Executor(); executor.setVisible(true); } }); } }