GetRequestURL() problem

Hi all,
I've a problem with getRequestURL().
I've an address like this : "https://www.testtest.com", but when I invoke request.getRequestURL() I receive in http so "http://www.testtest.com".
What could be the problem? Could it be something about java.security?
thanks in advance.

wkgrp wrote:
How can i check this to be sure?If you didn't install it, then ask the person who did install it. If you did install it then no, you're not running a separate HTTP server in front of the servlet container. Unless you install things without knowing about it :/
Note that this is not the IBM forum, its on their own website. There you'll find people who use Websphere, who might just know how to help you.

Similar Messages

Java EE 5 request.getRequestURL() change

Hello,
I have a problem with change of the method HttpServletRequest.getRequestURL() in my action servlets. I have this situation:
URL matches http://server/app/page-key-word-string
These URLs generates 404 Tomcat error page, which redirects to redirectServlet, where I get the client URL by calling request.getRequestURL() and then I parse the page-key-word-string and select the matching page from DB.
This worked fine in Java EE 1.4 but in Java EE 5 the getRequestURL() method returns the path to redirectServlet instead of the client URL. Please, where can I get the client URL? Or is there other way to implement these functionality?
Thanks a lot.

Hmm.. Do you mean response.redirect() or forward via RequestDispatcher? A redirect issues a new GET request from the client, changing the url returned from getRequestURL() so the behavior via J2EE 5 is more understandable. I'm not sure how the process worked for you using J2EE 4 unless you were using the RequestDispatcher and changed your code... But maybe there's more to this..

Problems with servlet filters

Hello,
I'm trying to implement filters for some of the examples presented in the j2ee tutorial. Thus, I've realized a very simple filter that works very well for the Converter example (mapped to the index.jsp URL). But this filter doesn't work with the Duke's Bank application and I don't understand why. I've tried to map this filter to the Dispatcher servlet and also to different URLs, the filter is actually executed, but the client gets no response from the server.
Here's the source code for my filter :
package com.sun.ebank.web.filters;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public final class MyFilter implements Filter {
private FilterConfig filterConfig = null;
public void init(FilterConfig filterConfig) throws ServletException {
this.filterConfig = filterConfig;
public void destroy() {
this.filterConfig = null;
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
if (filterConfig == null) return;
HttpServletRequest hr = (HttpServletRequest)request;
System.out.println ("MyFilter : " + hr.getMethod () + " URL=" + hr.getRequestURL () + " QueryString={" + hr.getQueryString () + "}");
chain.doFilter(request, response);
public String toString() {
if (filterConfig ==null) return ("MyFilter()");
StringBuffer sb = new StringBuffer("MyFilter(");
sb.append(filterConfig);
sb.append(")");
return (sb.toString());
Can anybody help me?
Thanks,
B.F.

As you're not actually doing anything in this filter but a quick System.out.print, there doesn't appear to be a problem with the filter code.
What does your web.xml file look like?
Does your IDE allow you to trace through the filter to the next target in the chain? If so, where does the code die? If not, use System.out.print statements to determine how far into the code you get.
No response to the client usually means that the response didn't have any content set. You can verify this by checking the state of the response object after doFilter has been called; if the headers haven't been set then something crashed in a bad way.
Good luck!

WL 6.1sp1&sp2 BUG: HttpServletRequest.getRequestURL()

          HttpServletRequest.getRequestURL() always returns "http://..." even if the request
          was made with "https://...". The fix is to replace the protocol specification with
          the results from getScheme() like so:
          StringBuffer aURL = request.getRequestURL();
          // broken on WL 6.1 -- need to correct the scheme
          aURL = aURL.replace(0, aURL.toString().indexOf(':'),
          request.getScheme());


Tonna I wrote:
          > Hi there,
          > Which version was this bug resolved in? Is it still outstanding in WL6.1sp4?
          > We?re currently using WL6.1sp2?if it?s resolved in WL6.1SP4 we may consider upgrading
          > instead of putting in a fix.
          >
          > Cheers
          > Tonna
          >
          > Nagesh Susarla <[email protected]> wrote:
          >
          >>thanks for pointing this out!
          >>its indeed a bug
          >>
          >>Steve Ditlinger wrote:
          >>
          >>>HttpServletRequest.getRequestURL() always returns "http://..." even
          >>
          >>if the request
          >>
          >>>was made with "https://...". The fix is to replace the protocol specification
          >>
          >>with
          >>
          >>>the results from getScheme() like so:
          >>>
          >>> StringBuffer aURL = request.getRequestURL();
          >>> // broken on WL 6.1 -- need to correct the scheme
          >>> aURL = aURL.replace(0, aURL.toString().indexOf(':'),
          >>>request.getScheme());
          >
          >
          Yes the fix is a part of 61sp4. If you still have any issues with the
          above mentioned problem, or if you need a patch please contact support
          the associated bug-id : CR076389
          rgds
          Nagesh

Javax.servlet.http.getRequestURL

Hello,
i�m using tomcat-4.1.34, and we use getRequestURL. We have a problem, getRequestUrl is returning the name of jsp is executing, and no the url.
In tomcat-4.1.31 is ok.
what happens??
thanks in advance

"DEPRECATED: As of Java(tm) Servlet API 2.3. These methods were only useful with the default encoding and have been moved to the request interfaces. "
You will find the getRequestURL() method in HttpServletRequest. The parsePostData() method and parseQueryString() methods were replaced with an Enumeration from ServletRequest.getAttributeNames() that is used to get Objects from ServletRequest.getAttribute(String name).
HTH.

Proxy redirect problem

I'm having a redirect problem going through a weblogic proxy. An app I was using appears to be redirecting the browser always to localhost:7121 which won't work with access via the my domain.
To explain fully I set up a test JSP page which outputs request.getRequestURL().toString() so I could trace what was happening. The weblogic configuration is explained below:
I'm using Weblogic 8.1 sp5. I've setup a 4 instances: a proxy (port 7120), redirector (port 7121) and cluster (two instances running on 7131, 7132)
If I navigate to:
http://localhost:7120/myapp/test.jsp my test page outputs: request.getRequestURL().toString() : http://localhost:7121/myapp/test.jsp
and again to:
http://localhost:7131/myapp/test.jsp my test page outputs: request.getRequestURL().toString() : http://localhost:7121/myapp/test.jsp
or
http://localhost:7132/myapp/test.jsp my test page outputs: request.getRequestURL().toString() : http://localhost:7121/myapp/test.jsp
The output is always the same ... it always says the requestURL is from localhost:7121 the redirector?
Can anyone help explain why I always get the same output? It is completely baffling me.
Thanks,
Matt
Edited by: user5673380 on Oct 15, 2008 3:52 PM

The problem was caused by incorrect configuration of FrontEndHttpPort and FrontEndListener and FrontEndHost in the cluster configuration. These values were incorrectly during config wizard install.

Httpservlet doPost() problem

Hi everyone,
I'm having trouble with httpServlet. I can't seem to make a doPost() happen.
Here's my problem:
Everytime I click on the submit button on the html whether it is the "submit post" or "submit get". The text that appears on the console is "doGet". I never get a "doPost". I tried overriding the service method (which I commented out right now), to see what the method type of the request is and it is always GET even if I submitted using post.
Is there something wrong with my code? Or am I not just understanding how doPost() works correctly. I'm really stumped, I don't know what else to do.Any help would be appreciated.
here is my simple html form:
<html><head><title>tester</title></head>
<form name="input" action=http://localhost:8080/testSevlet method="get">
Username:
<input type="text" name="user">
<input type="submit" value="Submit get">
</form>
<form name="input" action=http://localhost:8080/testSevlet method="post">
Username:
<input type="text" name="user">
<input type="submit" value="Submit post">
</form>
Here's my processing servlet
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
public class testServlet extends HttpServlet
public testServlet)
super();
public void init() throws ServletException
super.init();
public void destroy()
super.destroy();
public void service(HttpServletRequest req, HttpServletResponse res)
throws ServletException,IOException
System.out.println(req.getMethod());
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException
System.out.println("doGet");
public void doPost(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException
System.out.println("doPost");
}

I'm having a similar problem with POST and HttpServlet in Tomcat 5.0.25 and JDK 1.5.0_06-b05
The problem appears to be performing a POST to an HttpServlet before performing a GET.
Using a very simple form test.html:
<html>
<body>
<form method="post" action="http://localhost/test" name="request">
<textarea rows="10" cols="60" name="textarea">
some sample text
</textarea>
<input type="submit" name="submit" value="Ok">
</form>
</body>
</html>--------------------
If I load this form from Tomcat as http://localhost/test/test.html and click the Ok button, my test HttpServlet works fine, and outputs the following debug info:
req.getRequestURL: http://localhost/test/
req.getContentLength: 30
req.getContentType: application/x-www-form-urlencoded
req.getMethod: POST
req.getProtocol: HTTP/1.1
Request.Headers
accept=image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*
referer=http://localhost/test/test.html
accept-language=en-us
content-type=application/x-www-form-urlencoded
accept-encoding=gzip, deflate
user-agent=Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)
host=localhost
content-length=30
connection=Keep-Alive
cache-control=no-cache
Request.Parameters
xml=some sample text
submit=Ok--------------------------------
However, if I load the same html file into the browser from the filesystem (e.g., C:\Program Files\Apache Software Foundation\Tomcat 5.0\webapps\test\test.html) and click OK, I get the following output:
req.getRequestURL: http://localhost/test/
req.getContentLength: -1
req.getContentType: null
req.getMethod: GET
req.getProtocol: HTTP/1.1
Request.Headers
accept=image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*
accept-language=en-us
accept-encoding=gzip, deflate
user-agent=Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)
host=localhost
connection=Keep-Alive
cache-control=no-cache
Request.Parameters--------------------------------------
Highlighting the differences:
In the first case -- when the form is POSTed after GETting the form through Tomcat, things are correct:
* the method is POST
* the content-length and content-type are set appropriately
* the request parameters (from req.getParameter()) are correct
However, when the form is POSTed after being opened from the filesystem, HttpServlet has done some strange things:
* the method has changed to GET
* the content-length has changed to -1, and the content-type isn't set
* the content-length and content-type HTTP headers are gone
* there are no request parameters
In both cases, I've verified that the browser is outputting the same HTTP (with the exception of the referer header, which is missing if the form was opened from the filesystem):
POST / HTTP/1.1
Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*
Accept-Language: en-us
Content-Type: application/x-www-form-urlencoded
Accept-Encoding: gzip, deflate
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)
Host: localhost:8002
Content-Length: 41
Connection: Keep-Alive
Cache-Control: no-cache
textarea=some+sample+text%0D%0A&submit=Ok
Why is HttpServlet responding differently to effectively the same HTTP? The only difference is the Referer header -- I don't see why that should matter....
Any help here would be much appreciated!
Thanks,
Gerald

Querry string problem

hello
I am facing a problem while working with jsf
the problem is
i have implemented a filter which redirects a user to login page if he is no loggen in now
in this filter class i set a parameter in querry string which is the address of the previous from where it is redirected because he is not logged in.
uptill now every thing is fine ie in the login page i can see the querry string append in url now on this page when user enters password etc it is varified from data base if valid then i wana redirect the the user to the page that is appended in the querry string how can i do that????
In short
how can i get the query string in beans action listener which is on a command button of login page???
regards
Shakeel Abbas

hai BalusC
u r right very soon i am gona take english language course.
thanks for reply but how can i get the querry string in action method of command button
and u fellow Selvakumar have a look.
<filter>
<filter-name>AccessFilter</filter-name>
<filter-class>com.yourcompany.AccessFilter</filter-class>
<init-param>
<param-name>loginPage</param-name>
<param-value>login.faces</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>AccessFilter</filter-name>
<url-pattern>/reports/*</url-pattern>
</filter-mapping>
i used this in web.xml
and in the filter class i used is
public class AccessFilter implements Filter {
     private FilterConfig config;
     public void destroy() {
          // TODO Auto-generated method stub
     public void doFilter(ServletRequest request, ServletResponse response,
               FilterChain chain) throws IOException, ServletException {
          // TODO Auto-generated method stub
          HttpServletRequest servletRequest=((HttpServletRequest) request);
          HttpSession session = servletRequest.getSession();
          String url=servletRequest.getRequestURL().toString();
          url=url.substring(url.indexOf('/')+1);
          url=url.substring(url.indexOf('/')+1);
          url=url.substring(url.indexOf('/')+1);
          url=url.substring(url.indexOf('/')+1);
          if (session.getAttribute("loggedUser") == null) // if user is not logged
                                                                      // in
               HttpServletRequest req = (HttpServletRequest) request;
               String contextPath = req.getContextPath();
               String loginPage = config.getInitParameter("loginPage");
               String gotoPage=contextPath+"/"+loginPage+"?previousPage="+url;
               HttpServletResponse res = (HttpServletResponse) response;
               session.setAttribute("url", url);
               res.sendRedirect(gotoPage); // then redirect to loginPage
          } else {
               chain.doFilter(request, response);
     public void init(FilterConfig filterConfig) throws ServletException {
          // TODO Auto-generated method stub
          this.config = filterConfig;
I hope this may be help ful to u
regards
Shakeel Abbas
Edited by: Shakeel.Abbas on Sep 23, 2008 7:45 AM

GetRequestURL() and aliased URLs

I've just updated from Tomcat 5.0 to Tomcat 6.0, which also means that I've moved from Servlet 2.3 to Servlet 2.5.
We have a useful old programme that tracks clicks from search engines and at some point saves the URL requested by the user.
The programme uses request.getRequestURL().
That's fine up to a point, but the problem is that, since I changed to Tomcat 6, getRequestURL() is ignoring aliases, and is storing the path to the underlying .jsp.
For example:
The alias url seen by the user might be www.mysite.com/cars/VauxhallViva.jsp which is actually an alias for www.mysite.com/Cars.jsp?type=Vauxhall+Viva.
And the point is that since Tomcat6, getRequestURL is returning the url www.mysite.com/Cars.jsp?type=Vauxhall+Viva (the underlying .jsp) which is not what I want.
I've searched all over the place, but haven't found anything from other people related to this problem, and whatever I try, I can't manage to get to the alias that the user sees by any of the other methods available in the servlet api.
Any help with this apparently banal problem would be much appreciated.

Thanks very much for your reply. So that's why everything suddenly changed.
But unfortunately there's no RequestDispatcher involved with clicks from search engines, and only rarely have I used RequestDispatcher in my programmes. Perhaps jsp:forwards use it, I'll have to check.
The long and short of it is that there appears to be no way in the Servlet API to get to the url the user sees and uses. In other words if there's an alias, you can't get to it, which is odd: actually in my case it's very inconvenient, as I work(ed) with aliases a lot.
Apache knows all about it, but not Tomcat.
Surely there's a case here for an addition to the API, I would certainly find it very useful to know the alias in certain conditions? Luckily I think I had a fallback to the underlying .jsp in all cases, but I'm going to have to thoroughly check all my sites...
Thanks again for your help.

A problem with threads

I am trying to implement some kind of a server listening for requests. The listener part of the app, is a daemon thread that listens for connections and instantiates a handling daemon thread once it gets some. However, my problem is that i must be able to kill the listening thread at the user's will (say via a sto button). I have done this via the Sun's proposed way, by testing a boolean flag in the loop, which is set to false when i wish to kill the thread. The problem with this thing is the following...
Once the thread starts excecuting, it will test the flag, find it true and enter the loop. At some point it will LOCK on the server socket waiting for connection. Unless some client actually connects, it will keep on listening indefinatelly whithought ever bothering to check for the flag again (no matter how many times you set the damn thing to false).
My question is this: Is there any real, non-theoretical, applied way to stop thread in java safely?
Thank you in advance,
Lefty

This was one solution from the socket programming forum, have you tried this??
public Thread MyThread extends Thread{
     boolean active = true;
     public void run(){
          ss.setSoTimeout(90);
          while (active){
               try{
                    serverSocket = ss.accept();
               catch (SocketTimeoutException ste){
               // do nothing
     // interrupt thread
     public void deactivate(){
          active = false;
          // you gotta sleep for a time longer than the
          // accept() timeout to make sure that timeout is finished.
          try{
               sleep(91);
          }catch (InterruptedException ie){
          interrupt();
}

A problem with Threads and MMapi

I am tring to execute a class based on Game canvas.
The problem begin when I try to Play both a MIDI tone and to run an infinit Thread loop.
The MIDI tone "Stammers".
How to over come the problem?
Thanks in advance
Kobi
See Code example below:
import java.io.IOException;
import java.io.InputStream;
import javax.microedition.lcdui.Graphics;
import javax.microedition.lcdui.Image;
import javax.microedition.lcdui.game.GameCanvas;
import javax.microedition.media.Manager;
import javax.microedition.media.MediaException;
import javax.microedition.media.Player;
public class MainScreenCanvas extends GameCanvas implements Runnable {
     private MainMIDlet parent;
     private boolean mTrucking = false;
     Image imgBackgound = null;
     int imgBackgoundX = 0, imgBackgoundY = 0;
     Player player;
     public MainScreenCanvas(MainMIDlet parent)
          super(true);
          this.parent = parent;
          try
               imgBackgound = Image.createImage("/images/area03_bkg0.png");
               imgBackgoundX = this.getWidth() - imgBackgound.getWidth();
               imgBackgoundY = this.getHeight() - imgBackgound.getHeight();
          catch(Exception e)
               System.out.println(e.getMessage());
      * starts thread
     public void start()
          mTrucking = true;
          Thread t = new Thread(this);
          t.start();
      * stops thread
     public void stop()
          mTrucking = false;
     public void play()
          try
               InputStream is = getClass().getResourceAsStream("/sounds/scale.mid");
               player = Manager.createPlayer(is, "audio/midi");
               player.setLoopCount(-1);
               player.prefetch();
               player.start();
          catch(Exception e)
               System.out.println(e.getMessage());
     public void run()
          Graphics g = getGraphics();
          play();
          while (true)
               tick();
               input();
               render(g);
      * responsible for object movements
     private void tick()
      * response to key input
     private void input()
          int keyStates = getKeyStates();
          if ((keyStates & LEFT_PRESSED) != 0)
               imgBackgoundX++;
               if (imgBackgoundX > 0)
                    imgBackgoundX = 0;
          if ((keyStates & RIGHT_PRESSED) != 0)
               imgBackgoundX--;
               if (imgBackgoundX < this.getWidth() - imgBackgound.getWidth())
                    imgBackgoundX = this.getWidth() - imgBackgound.getWidth();
      * Responsible for the drawing
      * @param g
     private void render(Graphics g)
          g.drawImage(imgBackgound, imgBackgoundX, imgBackgoundY, Graphics.TOP | Graphics.LEFT);
          this.flushGraphics();
}

You can also try to provide a greater Priority to your player thread so that it gains the CPU time when ever it needs it and don't harm the playback.
However a loop in a Thread and that to an infinite loop is one kind of very bad programming, 'cuz the loop eats up most of your CPU time which in turn adds up more delays of the execution of other tasks (just as in your case it is the playback). By witting codes bit efficiently and planning out the architectural execution flow of the app before start writing the code helps solve these kind of issues.
You can go through [this simple tutorial|http://oreilly.com/catalog/expjava/excerpt/index.html] about Basics of Java and Threads to know more about threads.
Regds,
SD
N.B. And yes there are more articles and tutorials available but much of them targets the Java SE / EE, but if you want to read them here is [another great one straight from SUN|http://java.sun.com/docs/books/tutorial/essential/concurrency/index.html] .
Edited by: find_suvro@SDN on 7 Nov, 2008 12:00 PM

J2ME problem with threads

Hi all,
I would like to ask you for a help. I need to write a small program at my university. I started to write a midlet which function would be to countdown time for sports activities. I woul like to start a new thread - the one that counts down - and at the same time make the main thread sleep. After the "countdown" thread finishes, the main thread wakes up and waits for user input. The problem is that when the "countdown" thread finishes his work, I've got Uncaught exception java/lang/NullPointerException. error and the midlet halts.
Below you can find the code
import java.lang.*;
import java.util.*;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
public class intervals extends MIDlet implements CommandListener
public Display ekran;
private SweepCanvas sweeper;
private Form rundy;
private TextField round0, round1, round2, round3, round4, round5, round6, round7, round8;
private long czas,x;
private Command exitCommand;
private Command addRound;
private Command delRound;
private Command start;
private TextField repeat;
private Form odliczanie;
private Alert ostrz;
Licznik thread;
String test;
StringItem test1;
int parz,i,j,k;
static int l;
int ilrund;
int ilpowt;
Item sec;
long sec1;
public intervals()
    rundy = new Form("Interwały sportowe");
    exitCommand = new Command("Wyjście", Command.EXIT, 2);
    addRound = new Command("Dodaj","Dodaj rundę", Command.ITEM,1);
    delRound = new Command("Usuń","Usuń ostatnią rundę", Command.ITEM,1);
    start = new Command("Start", Command.ITEM,1);
    odliczanie = new Form("Odliczanie");
    TextField dodaj(TextField kolej)
        kolej=new TextField("Podaj czas (s) rundy "+parz,null, 4, TextField.NUMERIC);//stworzenie nowej instancji do wybierania czasu trwania rundy
        if(rundy.size()==0)
            rundy.insert(rundy.size(),kolej);
            else
                rundy.insert(rundy.size()-1, kolej);
        return kolej;
    void odliczanie(TextField round)
        monitor m=new monitor();
        k=Integer.parseInt(round.getString());
        ekran.setCurrent(odliczanie);
        thread=new Licznik(k,odliczanie);
        thread.start();
        ekran.setCurrent(rundy);
public void startApp()// throws MIDletStateChangeException
    rundy.deleteAll();
    repeat = new TextField("Podaj ilość powtórzeń",null,1,TextField.NUMERIC);
    rundy.addCommand(addRound);
    rundy.addCommand(exitCommand);
    rundy.setCommandListener(this);
    Canvas obrazek = new MyCanvas();
    ekran = Display.getDisplay(this);
    ekran.setCurrent(obrazek);
    czas=System.currentTimeMillis();
    while (System.currentTimeMillis()<czas+1000)
        continue;
    ekran.setCurrent(rundy);
public void pauseApp()
public void destroyApp(boolean unconditional)
    notifyDestroyed();
public void commandAction(Command c, Displayable s)
    if (c == exitCommand)
        destroyApp(false);
        notifyDestroyed();
    else if(c==addRound)
        if(rundy.size()==0)//Sprawdzenie ilości elementów w celu poprawnego wyświetlania liczby rund w formie
            parz=1;
            else
            parz=rundy.size();
        switch(parz)
            case 1:
                round0=dodaj(round0);break;
            case 2:
                round1=dodaj(round1);break;
            case 3:
               round2= dodaj(round2);break;
            case 4:
                round3=dodaj(round3);break;
            case 5:
                round4=dodaj(round4);break;
            default:
                ostrz=new Alert("Uwaga","Maksymalna liczba rund wynosi 9", null, AlertType.INFO);
                ostrz.setTimeout(3000);
                ekran.setCurrent(ostrz);
        if(rundy.size()==1)
            rundy.append(repeat);
            rundy.addCommand(start);
        rundy.addCommand(delRound);
    else if(c==delRound)
        if(rundy.size()!=0)
            rundy.delete(rundy.size()-2);
            if (rundy.size()==1)
                rundy.deleteAll();
            if(rundy.size()==0)
                rundy.removeCommand(delRound);
                rundy.removeCommand(start);
    else if(c==start)
        ilrund=rundy.size()-1;
        if(this.repeat.size()>0)
            ilpowt=Integer.parseInt(this.repeat.getString());
        ekran = Display.getDisplay(this);
        for (i=1; i<=ilpowt;i++)
            odliczanie= new Form("Odliczanie");
             for (j=0;j<ilrund;j++)
                switch(j)
                     case 0:
                         odliczanie(round0);
                         break;
                     case 1:
                         odliczanie(round1);
                         break;
                     case 2:
                         odliczanie(round2);
                         break;
                     case 3:
                         odliczanie(round3);
                         break;
                     case 4:
                         odliczanie(round4);
                         break;
                     case 5:
                         odliczanie(round5);
                         break;
                     case 6:
                         odliczanie(round6);
                         break;
                     case 7:
                         odliczanie(round7);
                         break;
                     case 8:
                         odliczanie(round8);
                         break;
class Licznik extends Thread
    int czas1,k;
    Form forma;
    monitor m;
    public Licznik(int k,Form formap)
        czas1=k;
        forma=formap;
    public synchronized void run()
        while(czas1>0)
            forma.deleteAll();
            forma.append("Czas pozostały (s): "+czas1);
            try{Thread.sleep(1000);} catch(InterruptedException e){e.printStackTrace();}
            czas1--;
        if(czas1<=0)
            m.put();
    }and monitor class
public class monitor
boolean busy=false;
synchronized void get()
    if(!busy)
        try
            wait();
        }catch(InterruptedException e){e.printStackTrace();}
    notify();
synchronized void put()
    if(busy)
        try
        wait();
        }catch(InterruptedException e){e.printStackTrace();}
    busy=true;
    notify();
}Can anybody help me with this?

Groovemaker,
Your Licznik class has a member m of type monitor, which has not been instantiated (in other words is null) hence, when calling m.put() you get NullPointerException. Please also mind, that using Thread.sleep(1000) is not an accurate way of measuring time.
If I may, please use recommended for Java class naming conventions - some of your names use lower case, while other don't which is confusing to the reader.
Daniel

Problem with threads within applet

Hello,
I got an applet, inside this applet I have a singleton, inside this singleton I have a thread.
this thread is running in endless loop.
he is doing something and go to sleep on and on.
the problem is,
when I refresh my IE6 browser I see more than 1 thread.
for debug matter, I did the following things:
inside the thread, sysout every time he goes to sleep.
sysout in the singleton constructor.
sysout in the singleton destructor.
the output goes like this:
when refresh the page, the singleton constructor loading but not every refresh, sometimes I see the constructor output and sometimes I dont.
The thread inside the singleton is giving me the same output, sometime I see more than one thread at a time and sometimes I dont.
The destructor never works (no output there).
I don't understand what is going on.
someone can please shed some light?
thanks.
btw. I am working with JRE 1.1
this is very old and big applet and I can't convert it to something new.

Ooops. sorry!
I did.
     public void start() {
     public void stop() {
     public void destroy() {
          try {
               resetAll();
               Configuration.closeConnection();
               QuoteItem.closeConnection();
          } finally {
               try {
                    super.finalize();
               } catch (Throwable e) {
                    e.printStackTrace();
     }

Problem with Threads and a static variable

I have a problem with the code below. I am yet to make sure that I understand the problem. Correct me if I am wrong please.
Code functionality:
A timer calls SetState every second. It sets the state and sets boolean variable "changed" to true. Then notifies a main process thread to check if the state changed to send a message.
The problem as far I understand is:
Assume the timer Thread calls SetState twice before the main process Thread runs. As a result, "changed" is set to true twice. However, since the main process is blocked twice during the two calls to SetState, when it runs it would have the two SetState timer threads blocked on its synchronized body. It will pass the first one, send the message and set "changed" to false since it was true. Now, it will pass the second thread, but here is the problem, "changed" is already set to false. As a result, it won't send the message even though it is supposed to.
Would you please let me know if my understanding is correct? If so, what would you propose to resolve the problem? Should I call wait some other or should I notify in a different way?
Thanks,
B.D.
Code:
private static volatile boolean bChanged = false;
private static Thread objMainProcess;
   protected static void Init(){
        objMainProcess = new Thread() {
            public void run() {
                while( objMainProcess == Thread.currentThread() ) {
                   GetState();
        objMainProcess.setDaemon( true );
        objMainProcess.start();
    public static void initStatusTimer(){
        if(objTimer == null)
             objTimer = new javax.swing.Timer( 1000, new java.awt.event.ActionListener(){
                public void actionPerformed( java.awt.event.ActionEvent evt){
                          SetState();
    private static void SetState(){
        if( objMainProcess == null ) return;
        synchronized( objMainProcess ) {
            bChanged = true;
            try{
                objMainProcess.notify();
            }catch( IllegalMonitorStateException e ) {}
    private static boolean GetState() {
        if( objMainProcess == null ) return false;
        synchronized( objMainProcess ) {
            if( bChanged) {
                SendMessage();
                bChanged = false;
                return true;
            try {
                objMainProcess.wait();
            }catch( InterruptedException e ) {}
            return false;
    }

Thanks DrClap for your reply. Everything you said is right. It is not easy to make them alternate since SetState() could be called from different places where the state could be anything else but a status message. Like a GREETING message for example. It is a handshaking message but not a status message.
Again as you said, There is a reason I can't call sendMessage() inside setState().
The only way I was able to do it is by having a counter of the number of notifies that have been called. Every time notify() is called a counter is incremented. Now instead of just checking if "changed" flag is true, I also check if notify counter is greater than zero. If both true, I send the message. If "changed" flag is false, I check again if the notify counter is greater than zero, I send the message. This way it works, but it is kind of a patch than a good design fix. I am yet to find a good solution.
Thanks,
B.D.

Problem with threads running javaw

Hi,
Having a problem with multi thread programming using client server sockets. The program works find when starting the the application in a console using java muti.java , but when using javaw multi.java the program doesnt die and have to kill it in the task manager. The program doesnt display any of my gui error messages either when the server disconnect the client. all works find in a console. any advice on this as I havent been able to understand why this is happening? any comment would be appreciated.
troy.

troy,
Try and post a minimum code sample of your app which
does not work.
When using javaw, make sure you redirect the standard
error and standard output streams to file.
Graeme.Hi Graeme,
I dont understand what you mean by redirection to file? some of my code below.
The code works fine under a console, code is supposed to exit when the client (the other server )disconnects. the problem is that but the clientworker side of the code still works. which under console it doesnt.
public class Server{
ServerSocket aServerSocket;
Socket dianosticsSocket;
Socket nPortExpress;
ClientListener aClientListener;
LinkedList queue = new LinkedList();
int port = 0;
int clientPort = 0;
String clientName = null;
boolean serverAlive = true;
* Server constructor generates a server
* Socket and then starts a client threads.
* @param aPort      socket port of local machine.
public Server(int aPort, String aClientName, int aClientPort){
port = aPort;
clientName = aClientName;
clientPort = aClientPort;
try{
// create a new thread
aServerSocket = new ServerSocket(port) ;
// connect to the nPortExpress
aClientListener = new ClientListener(InetAddress.getByName(clientName), clientPort, queue,this);
// aClientListener.setDaemon(true);
aClientListener.start();
// start a dianostic port
DiagnosticsServer aDiagnosticsServer = new DiagnosticsServer(port,queue,aClientListener);
// System.out.println("Server is running on port " + port + "...");
// System.out.println("Connect to nPort");
catch(Exception e)
// System.out.println("ERROR: Server port " + port + " not available");
JOptionPane.showMessageDialog(null, (e.toString()),"ERROR: Server port " + port + " not available", JOptionPane.ERROR_MESSAGE);
serverAlive = false;
System.exit(1);
while(serverAlive&&aClientListener.hostSocket.isConnected()){
try{
// connect the client
Socket aClient = aServerSocket.accept();
//System.out.println("open client connection");
//System.out.println("client local: "+ aClient.getLocalAddress().toString());
// System.out.println("client localport: "+ aClient.getLocalPort());
// System.out.println("client : "+ aClient.getInetAddress().toString());
// System.out.println("client port: "+ aClient.getLocalPort());
// make a new client thread
ClientWorker clientThread = new ClientWorker(aClient, queue, aClientListener, false);
// start thread
clientThread.start();
catch(Exception e)
//System.out.println("ERROR: Client connection failure");
JOptionPane.showMessageDialog(null, (e.toString()),"ERROR: Client connection failure", JOptionPane.ERROR_MESSAGE);
}// end while
} // end constructor Server
void serverExit(){
     JOptionPane.showMessageDialog(null, "Server ","ERROR: nPort Failure", JOptionPane.ERROR_MESSAGE);
     System.exit(1);
}// end class Server
*** connect to another server
public class ClientListener extends Thread{
InetAddress hostName;
int hostPort;
Socket hostSocket;
BufferedReader in;
PrintWriter out;
boolean loggedIn;
LinkedList queue;      // reference to Server queue
Server serverRef; // reference to main server
* ClientListener connects to the host server.
* @param aHostName is the name of the host eg server name or IP address.
* @param aHostPort is a port number of the host.
* @param aLoginName is the users login name.
public ClientListener(InetAddress aHostName, int aHostPort,LinkedList aQueue,Server aServer)      // reference to Server queue)
hostName = aHostName;
hostPort = aHostPort;
queue = aQueue;
serverRef = aServer;
// connect to the server
try{
hostSocket = new Socket(hostName, hostPort);
catch(IOException e){
//System.out.println("ERROR: Connection Host Failed");
JOptionPane.showMessageDialog(null, (e.toString()),"ERROR: Connection to nPort Failed", JOptionPane.ERROR_MESSAGE);
System.exit(0);
} // end constructor ClientListener
** multi client connection server
ClientWorker(Socket aSocket,LinkedList aQueue, ClientListener aClientListener, boolean diagnostics){
queue = aQueue;
addToQueue(this);
client = aSocket;
clientRef = aClientListener;
aDiagnostic = diagnostics;
} // end constructor ClientWorker
* run method is the main loop of the server program
* in change of handle new client connection as well
* as handle all messages and errors.
public void run(){
boolean alive = true;
String aSubString = "";
in = null;
out = null;
loginName = "";
loggedIn = false;
while (alive && client.isConnected()&& clientRef.hostSocket.isConnected()){
try{
in = new BufferedReader(new InputStreamReader(client.getInputStream()));
out = new PrintWriter(new OutputStreamWriter(client.getOutputStream()));
if(aDiagnostic){
out.println("WELCOME to diagnostics");
broadCastDia("Connect : diagnostics "+client.getInetAddress().toString());
out.flush();
else {
out.println("WELCOME to Troy's Server");
broadCastDia("Connect : client "+client.getInetAddress().toString());
     out.flush();
String line;
while(((line = in.readLine())!= null)){
StringTokenizer aStringToken = new StringTokenizer(line, " ");
if(!aDiagnostic){
broadCastDia(line);
clientRef.sendMessage(line); // send mesage out to netExpress
out.println(line);
out.flush();
else{
if(line.equals("GETIPS"))
getIPs();
else{
clientRef.sendMessage(line); // send mesage out to netExpress
out.println(line);
out.flush();
} // end while
catch(Exception e){
// System.out.println("ERROR:Client Connection reset");
                         JOptionPane.showMessageDialog(null, (e.toString()),"ERROR:Client Connection reset", JOptionPane.ERROR_MESSAGE);
try{
if(aDiagnostic){
broadCastDia("Disconnect : diagnostics "+client.getInetAddress().toString());
out.flush();
else {
broadCastDia("Disconnect : client "+client.getInetAddress().toString());
     out.flush();
// close the buffers and connection;
in.close();
out.close();
client.close();
// System.out.println("out");
// remove from list
removeThreadQueue(this);
alive = false;
catch(Exception e){
// System.out.println("ERROR: Client Connection reset failure");
JOptionPane.showMessageDialog(null, (e.toString()),"ERROR: Client Connection reset failure", JOptionPane.ERROR_MESSAGE);
}// end while
} // end method run
* method run - Generates io stream for communicating with the server and
* starts the client gui. Run also parses the input commands from the server.
public void run(){
boolean alive = true;
try{
// begin to life the gui
// aGuiClient = new ClientGui(hostName.getHostName(), hostPort, loginName, this);
// aGuiClient.show();
in = new BufferedReader(new InputStreamReader(hostSocket.getInputStream()));
out = new PrintWriter(new OutputStreamWriter(hostSocket.getOutputStream()));
while (alive && hostSocket.isConnected()){
String line;
while(((line = in.readLine())!= null)){
System.out.println(line);
broadCast(line);
} // end while
} // end while
catch(Exception e){
//     System.out.println("ERRORa Connection to host reset");
JOptionPane.showMessageDialog(null, (e.toString()),"ERROR: Connection to nPort reset", JOptionPane.ERROR_MESSAGE);
try{
hostSocket.close();
     }catch(Exception a){
     JOptionPane.showMessageDialog(null, (a.toString()),"ERROR: Exception", JOptionPane.ERROR_MESSAGE);
alive = false;
System.exit(1);
} // end method run

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