Re: ClassNotFound again :-( Java 6 Extending Dialog Please help

From:
"Richard Maher" <maher_rj@hotspamnotmail.com>
Newsgroups:
comp.lang.java.programmer
Date:
Sun, 4 Feb 2007 07:34:04 +0800
Message-ID:
<eq32b8$p80$1@news-01.bur.connect.com.au>
"none" <""tim\"@(none)"> wrote in message
news:45c4ce7c$0$27099$db0fefd9@news.zen.co.uk...

Richard Maher wrote:

Hi,

[I'm floundering - please help]

Below is the short and simple code for my 4 classes: -

LogApp.java - Applet driver code
Tier3Socket.java - Sets up and authorizes communication with the server
Tier3Logon.java - Dialog box for Username/Password
*Tier3Welcome.java - Dialog box to display Last Login time/Login

failures

etc
(Tier3Socket$Message.class) - Haven't sorted out main message passing

yet

(Javascript)

(*) This appears to be the troublemaker.
[Java.lang.ClassNotFoundException:LogApp]

All sourcefiles have been Javac'd and all classes have been Jar'd.

(Manifest

looks good)

If I remove any reference in LogApp to Tier3Welcome (and don't archive

it)

everything is great! I get a dialog box, authorization either succeeds

or

fails, and everything is peachy. So what am I, and Tier3Welcome, doing
wrong? All I want to do is (on successful authorization) pop-up a second

box

that displays some verification details, and asks the user to click OK.

1) Can you only Extend Dialog once per (some Java unit of work)

Interfaces?

2) Is it because I using the default package
3) Is it because I'm using the command line for JAR and am not JARing

all

classes in the directory?
4) Typo?
5) Name and method scoping issues?

Cheers Richard Maher

PS. Once again, I am a newbie so appologies if it's simple. BTW Windows

2000

LogApp.java
===========

import java.applet.Applet;
import java.awt.*;
import java.net.*;
import java.io.IOException;

import java.util.Date;
import java.util.Properties;

public class LogApp extends Applet
{
    String Username = "";
    String Password = "";
    Boolean Pass = false;
    Tier3Socket Pipe;

    public void init()
    {
        if (!Authorize())
        {
            try
             {
               getAppletContext().showDocument
                   (new URL (getCodeBase()+"accessdenied.html"),"_top");
             }
            catch (Exception e) {e.printStackTrace(); }
        }
    }

    public boolean Authorize()
    {
        System.out.println("Step 1");
        int Port = Integer.parseInt(getParameter("PORT"));
        String Appl = getParameter("APPLICATION");
        System.out.println("Step 2");
        Pipe = new Tier3Socket(getCodeBase().getHost(),Port);
        System.out.println("Step 3");

        try {Pipe.open();} catch (Exception e) {return false;}
        System.out.println("Step 4");

        Object ParentFrame = getParent();
        while ((ParentFrame != null) &&
                !(ParentFrame instanceof Frame))
                {
                ParentFrame = ((Component)ParentFrame).getParent();
                }

        Frame Creds = (Frame)ParentFrame;

        Tier3Logon Logon = new Tier3Logon(Creds);

        requestFocus();

        if (Logon.LogonAborted)
            {
            System.out.println("Logon Aborted");
            }
        else
            {
            Username = Logon.InUser.getText();
            Password = Logon.InPass.getText();

            Pass = true;
            try {Pipe.handShake(Username, Password);}
            catch (Exception e)
                {
                  Pass = false;
                  e.printStackTrace();
                  System.out.println("Logon Failed");
                }
            }

        if (Pass && Logon.Cb.getState())
        {
// Tier3Welcome Welcome = new Tier3Welcome(Creds, Appl,
Pipe.t3IdBuf);
// requestFocus();
// Welcome.dispose();
        }

        Logon.dispose();

        System.out.println("Step 5");
        return Pass;
    }

    public void destroy() {
    try
    {Pipe.close();}
    catch (IOException e)
          {e.printStackTrace();}

    super.destroy();
 }

}

Tier3Socket.java
================

import java.io.BufferedOutputStream;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import java.lang.System;

public class Tier3Socket
 {
 public static final
         String HOSTCHARSET="ISO-8859-1";
 public static final
         String T3ID = "T3$";
 public static final
         int MAXAPPMSG=510;
 public static final
         int HDRSIZ=2;
 public static final
         int USERSIZ=40;
 public static final
         int T3IDBUFSIZ=48;
 public static final
         int CREDBUFSIZ=80;

 public byte [] t3IdBuf;

 private String host;
 private int port;
 private Socket t3Sock;
 private BufferedInputStream in;
 private BufferedOutputStream out;
 private byte [] MsgHdr;
 private byte [] OutUser;
 private byte [] OutPwd;
 private byte [] CredBuf;

 private String inMsg;

 public class Message
 {
  String type;
  String message;
  Message (String type , String message)
  {
   this.type = type;
   this.message = message;
  }
  public String getMessage()
  {
   return message;
  }
  public String getType()
  {
   return type;
  }

 }
 Tier3Socket (String host, int port)
 {
  this.host = host;
  this.port = port;

  MsgHdr = new byte[HDRSIZ];
  t3IdBuf = new byte[T3IDBUFSIZ];
 }

 public void open() throws UnknownHostException, IOException
 {
  t3Sock = new Socket();

  t3Sock.setKeepAlive(new Boolean(true));
  t3Sock.setSoTimeout(new Integer(10000));
  t3Sock.setTcpNoDelay(new Boolean(true));

  t3Sock.connect(new InetSocketAddress(host,port), new Integer(3));

  in = new BufferedInputStream (t3Sock.getInputStream() ,MAXAPPMSG);
  out = new BufferedOutputStream (t3Sock.getOutputStream(),MAXAPPMSG);
 }

 public void handShake(String Username, String Password) throws

IOException

 {
  CredBuf = new byte[CREDBUFSIZ];

  OutUser = Username.getBytes(HOSTCHARSET);
  System.arraycopy(OutUser, 0, CredBuf, 0, OutUser.length);

  OutPwd = Password.getBytes(HOSTCHARSET);
  System.arraycopy(OutPwd, 0, CredBuf, USERSIZ, OutPwd.length);

  out.write(CredBuf, 0, CREDBUFSIZ);
  out.flush();

  if (in.read(t3IdBuf) < t3IdBuf.length)
  {
      System.out.println("Read < " + Integer.toString(t3IdBuf.length) +

"

read");
      throw new IOException();
  }

  inMsg = new String(t3IdBuf, 0, 3, HOSTCHARSET);

  if (!inMsg.equals(T3ID))
  {
      throw new IOException();
  }

 }

 public void close () throws IOException
 {
  if (t3Sock != null && !t3Sock.isClosed())
  {
      try {t3Sock.close();}
      catch (Exception e)
            {e.printStackTrace();}
  }
 }

 public void sendMessage (String type , String message) throws

IOException

 {
  byte [] msgtype = type.getBytes(HOSTCHARSET);
  byte [] msg = message.getBytes(HOSTCHARSET);

  out.write(msgtype);
  out.write(msg);
  out.flush();
 }

 public Message readMessage () throws IOException
 {

  if (in.read(MsgHdr, 0, HDRSIZ) < HDRSIZ)
  {
      throw new IOException();
  }

  String wholemsg = "Hello";
  String type = wholemsg.substring(0,2);
  String msg = wholemsg.substring(2);
  return new Message (type , msg);
 }

 public void initEmployeeRead (String employee) throws IOException
 {
  sendMessage ("20" , employee);
 }

 public String readNextEmployee () throws IOException
 {
  Message msg = readMessage ();
  if (msg.getType().equals("21"))
   return msg.getMessage().trim();
  return null;
 }
}

Tier3Logon.java
===============

import java.awt.*;
import java.awt.event.*;

public class Tier3Logon extends Dialog
                        implements ActionListener
{
    Label Headr = new Label("Server Authentication

Required",Label.LEFT);

    Label User = new Label("Username:", Label.RIGHT);
    Label Pass = new Label("Password:", Label.RIGHT);

    TextField InUser = new TextField(40);
    TextField InPass = new TextField(40);

    Button Okay = new Button("OK");
    Button Cncl = new Button("Cancel");

    Checkbox Cb = new Checkbox("Display logon confirmation",true);

    boolean LogonAborted = false;

    public Tier3Logon(Frame Dframe)
    {
        super(Dframe,"Tier3 Logon",true);

        setBackground(Color.white);

        Headr.setFont(new Font("Helvetica", Font.BOLD, 14));

        InPass.setEchoChar('*');

        Panel Top = new Panel();
        Top.setLayout(new GridLayout(1, 2, 8, 2));
        Top.add(Headr);
        Top.add(Cb);
        add("North", Top);

        Panel pc = new Panel();
        pc.setLayout(new GridLayout(2, 2, 8, 2));
        pc.add(User);
        pc.add(InUser);
        pc.add(Pass);
        pc.add(InPass);
        add("Center", pc);

        Okay.addActionListener(this);
        Cncl.addActionListener(this);

        Panel pb = new Panel();
        pb.add(Okay);
        pb.add(Cncl);
        add("South", pb);

        setBounds(50, 150, 300, 300);
        pack();
        setResizable(false);
        setVisible(true);
    }

    public void actionPerformed(ActionEvent ae)
    {
        if (ae.getSource() == Okay)
            {
            setVisible(false);
            }
        else
            {
            LogonAborted = true;
            setVisible(false);
            }
    }
}

Tier3Welcome.java
=================

import java.awt.*;
import java.awt.event.*;

public class Tier3Welcome extends Dialog
                          implements ActionListener
{
    Button Okay = new Button("OK");
    Label Label1 = new Label();

    public Tier3Welcome(Frame Wframe, String AppName, byte[] t3IdBuf)
    {
        super(Wframe,"Tier3 Confirmation",true);

        String Line1 = "Welcome to the " + AppName + " application via

TIER3

V" +
                       Byte.toString(t3IdBuf[3]) + "." +
Byte.toString(t3IdBuf[4]) +
                       " on node " + new String(t3IdBuf, 5, 6);

        Label1.setAlignment(Label.LEFT);
        Label1.setText(Line1);
        Label1.setFont(new Font("Helvetica", Font.BOLD, 14));

        Panel top = new Panel();
        top.setLayout(new GridLayout(2, 1, 0, 8));
        top.add(Label1);

        Okay.addActionListener(this);
        top.add(Okay);

        add("Center", top);

        setBounds(50, 150, 300, 300);
        pack();
        setResizable(false);
        setVisible(true);
    }

    public void actionPerformed(ActionEvent ae)
    {
        if (ae.getSource() == Okay)
            setVisible(false);
    }
}


if all files are compiled and include in your jar file it might be a
typo in your html applet/object tag (maybe the jar or codebase
attribute?). Also if you are testing this in a browser it might be wise
to clear the classloader cache via the java console after you redeploy.
i can't remember the hotkey to do this but i think its 'x'.

Tim Terry
www.devisland.net


Hi Tim,

Thanks for the reply.

The point is that if I remove the Tier3Welcome class then everything works
as expected. Tier3Welcome is either somehow corrupting the JAR file or the
Applet activation. Maybe a "Linker" for Java would be worthwhile :-) I'm
going to knock up a DoNothin class that doesn't extend dialog an see if that
works, and I'll also give the Appletviewer a guernsey and see what happens
there. But given my plebian mastery of the Java Language I had thought that
some simple schoolboy error would be sittin' up like a fly-shit in the sugar
bowl.

Tier3Welcome (above) is only about 40 lines long; any chance of having a
quick look at it (and probably Tier3Logon)?

A deplorable example of a procedural programmer trying to grapple with the
inherent beauty of an OO language? An ingnorance of constructors, super()
(and String equality comparisons) seldom exhibited outside of Java 1A? Or a
crappy language that should do a lot better at compile/link time error
detection than a loathesome runtime ClassNotFound :-)

Regards Richard Maher

PS. "Welcome" a reserved word/method? My inability to come to terms with
lowercasing the first letter of my objects leading to ambiguity?

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