import java.applet.*;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

/**
 * HelloApplet is a simple applet that toggles a message
 * when you click on a Draw button.
 */
public class HelloApplet extends JApplet {

    /** The flag which controls drawing the message. */
    protected boolean requested;

    /** init(  ) is an Applet method called by the browser to initialize */
    public void init(  ) {
        JButton b;
        requested = false;
        Container cp = (Container)getContentPane(  );
        cp.setLayout(new FlowLayout(  ));
        cp.add(b = new JButton("Draw/Don't Draw"));
        b.addActionListener(new ActionListener(  ) {
            /*  Button - toggle the state of the "requested" flag, to draw or
             *  not to draw.
             */
            public void actionPerformed(ActionEvent e) {
                String arg = e.getActionCommand(  );
                // Invert the state of the draw request.
                requested = !requested;
                do_the_work(  );
            }
        });
    }

    /** paint(  ) is an AWT Component method, called when the 
     *  component needs to be painted.
     */
    public void do_the_work(  ) {
        /* If the Draw button is selected, draw something */
        if (requested) {
            showStatus("Welcome to Java!");
        } else {
            showStatus("");    // retract welcome? :-)
        }
    }
}

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.applet.*;
import java.lang.reflect.*;
import java.net.*;
import java.util.*;

/*
 * AppletViewer - a simple Applet Viewer program.
 */
public class AppletViewer {
    /** The main Frame of this program */
    JFrame f;
    /** The AppletAdapter (gives AppletStub, AppletContext, showStatus) */
    static AppletAdapter aa = null;
    /** The name of the Applet subclass */
    String appName = null;
    /** The Class for the actual applet type */
    Class ac = null;
    /** The Applet instance we are running, or null. Can not be a JApplet
     * until all the entire world is converted to JApplet. */
    Applet ai = null;
    /** The width of the Applet */
    final int WIDTH = 250;
    /** The height of the Applet */
    final int HEIGHT = 200;

    /** Main is where it all starts. 
     * Construct the GUI. Load the Applet. Start it running.
     */
    public static void main(String[] av) {
        new AppletViewer(av.length==0?"HelloApplet":av[0]);
    }

    /** Construct the GUI for an Applet Viewer */
    AppletViewer(String appName) {
        super(  );

        this.appName = appName;

        f = new JFrame("AppletViewer");
        f.addWindowListener(new WindowAdapter(  ) {
            public void windowClosing(WindowEvent e) {
                f.setVisible(false);
                f.dispose(  );
                System.exit(0);
            }
        });
        Container cp = f.getContentPane(  );
        cp.setLayout(new BorderLayout(  ));

        // Instantiate the AppletAdapter which gives us
        // AppletStub and AppletContext.
        if (aa == null)
            aa = new AppletAdapter(  );

        // The AppletAdapter also gives us showStatus.
        // Therefore, must add(  ) it very early on, since the Applet's
        // Constructor or its init() may use showStatus(  )
        cp.add(BorderLayout.SOUTH, aa);

        showStatus("Loading Applet " + appName);

        loadApplet(appName , WIDTH, HEIGHT);    // sets ac and ai
        if (ai == null)
            return;

        // Now right away, tell the Applet how to find showStatus et al.
        ai.setStub(aa);

        // Connect the Applet to the Frame.
        cp.add(BorderLayout.CENTER, ai);

        Dimension d = ai.getSize(  );
        d.height += aa.getSize(  ).height;
        f.setSize(d);
        f.setVisible(true);        // make the Frame and all in it appear

        showStatus("Applet " + appName + " loaded");

        // Here we pretend to be a browser!
        ai.init(  );
        ai.start(  );
    }

    /*
     * Load the Applet into memory. Should do caching.
     */
    void loadApplet(String appletName, int w, int h) {
        // appletName = ... extract from the HTML CODE= somehow ...;
        // width =         ditto
        // height =         ditto
        try {
            // get a Class object for the Applet subclass
            ac = Class.forName(appletName);
            // Construct an instance (as if using no-argument constructor)
            ai = (Applet) ac.newInstance(  );
        } catch(ClassNotFoundException e) {
            showStatus("Applet subclass " + appletName + " did not load");
            return;
        } catch (Exception e ){
            showStatus("Applet " + appletName + " did not instantiate");
            return;
        }
        ai.setSize(w, h);
    }

    public void showStatus(String s) {
        aa.getAppletContext(  ).showStatus(s);
    }
}

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.net.*;
import java.util.*;

/*
 * AppletAdaptor: partial implementation of AppletStub and AppletContext.
 *
 * This code is far from finished, as you will see.
 *
 */
public class AppletAdapter extends Panel implements AppletStub, AppletContext {
    /** The status window at the bottom */
    Label status = null;

    /** Construct the GUI for an Applet Status window */
    AppletAdapter(  ) {
        super(  );

        // Must do this very early on, since the Applet's
        // Constructor or its init() may use showStatus(  )
        add(status = new Label(  ));

        // Give "status" the full width
        status.setSize(getSize().width, status.getSize(  ).height);

        showStatus("AppletAdapter constructed");    // now it can be said
    }

    /****************** AppletStub ***********************/
    /** Called when the applet wants to be resized.  */
    public void appletResize(int w, int h) {
        // applet.setSize(w, h);
    }

    /** Gets a reference to the applet's context.  */
    public AppletContext getAppletContext(  ) {
        return this;
    }

    /** Gets the base URL.  */
    public URL getCodeBase(  ) {
        return getClass(  ).getResource(".");
    }

    /** Gets the document URL.  */
    public URL getDocumentBase(  ) {
        return getClass(  ).getResource(".");
    }

    /** Returns the value of the named parameter in the HTML tag.  */
    public String getParameter(String name) {
        String value = null;
        return value;
    }
    /** Determines if the applet is active.  */
    public boolean isActive(  ) {
        return true;
    }

    /************************ AppletContext ************************/

    /** Finds and returns the applet with the given name. */
    public Applet getApplet(String an) {
        return null;
    }

    /** Finds all the applets in the document */
    public Enumeration getApplets(  )  {
        class AppletLister implements Enumeration {
            public boolean hasMoreElements(  ) {
                return false;
            }
            public Object nextElement(  ) {
                return null;
            }
        }
        return new AppletLister(  );
    }

    /** Create an audio clip for the given URL of a .au file */
    public AudioClip getAudioClip(URL u) {
        return null;
    }

    /** Look up and create an Image object that can be paint(  )ed */
    public Image getImage(URL u)  {
        return null;
    }

    /** Request to overlay the current page with a new one - ignored */
    public void showDocument(URL u) {
    }

    /** as above but with a Frame target */
    public void showDocument(URL u, String frame)  {
    }

    /** Called by the Applet to display a message in the bottom line */
    public void showStatus(String msg) {
        if (msg == null)
            msg = "";
        status.setText(msg);
    }
}