Launcher.java

import java.applet.Applet;
import java.applet.AppletContext;
import java.applet.AppletStub;
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.net.URL;
import javax.swing.JFrame;

public final class Launcher {
    private static final int DEFAULT_WIDTH = 800;
    private static final int DEFAULT_HEIGHT = 510;

    public static void main(String[] args) throws Exception {
        System.setProperty("java.awt.headless", "false");
        Class<?> clazz = Class.forName("Model2");
        Object instance = clazz.getDeclaredConstructor().newInstance();

        JFrame frame = new JFrame("LEGI Mechanism");
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.setLayout(new BorderLayout());

        if (instance instanceof Applet) {
            Applet applet = (Applet) instance;
            applet.setStub(new BasicAppletStub());
            applet.setPreferredSize(new Dimension(DEFAULT_WIDTH, DEFAULT_HEIGHT));
            applet.setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
            frame.add(applet, BorderLayout.CENTER);
            frame.pack();
            frame.setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
            frame.setLocationRelativeTo(null);
            frame.setVisible(true);
            applet.addNotify();
            applet.init();
            applet.start();
            applet.doLayout();
            applet.validate();
            frame.validate();

            frame.addWindowListener(new WindowAdapter() {
                @Override
                public void windowClosed(WindowEvent e) {
                    applet.stop();
                    applet.destroy();
                }
            });
        } else if (instance instanceof Component) {
            Component comp = (Component) instance;
            comp.setPreferredSize(new Dimension(DEFAULT_WIDTH, DEFAULT_HEIGHT));
            frame.add(comp, BorderLayout.CENTER);
            frame.pack();
            frame.setLocationRelativeTo(null);
            frame.setVisible(true);
        } else {
            throw new IllegalStateException("Model2 is not an Applet or Component");
        }
    }

    private static final class BasicAppletStub implements AppletStub {
        @Override
        public boolean isActive() {
            return true;
        }

        @Override
        public URL getDocumentBase() {
            return null;
        }

        @Override
        public URL getCodeBase() {
            return null;
        }

        @Override
        public String getParameter(String name) {
            return null;
        }

        @Override
        public AppletContext getAppletContext() {
            return null;
        }

        @Override
        public void appletResize(int width, int height) {
            // Let the frame manage sizing.
        }
    }
}