import javax.swing.*; public class EditorIF extends JFrame { public static void main(String[] args) { EditorIF jframe=new EditorIF(); EditorInternalFrame frame = new EditorInternalFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(640, 480); frame.show(); jframe.getContentPane().add(frame); jframe.show(); } }