Uploadbean problem

Hi
i am using the uploadbean from javazoom.com & it's working fine as far as upload is concerned. It uploads any file from my computer & stores it in my mysql database in a field of type longblob. So probably it is stored in binary form. When i try to read the file from my jsp page using jdbc & simple java statements the output of the file is in different format probably it displays the binary code itself. I want the file as it is uploaded. I am new to jsp. Pls help me as it is urgently required for my project.
Thanking u in advance

look on the servlet forum :
This is a cool solution:
http://users.boone.net/wbrameld/multipartformdata/
com.bigfoot.bugar.servlet.http.MultipartFormData
Allows JSPs and Servlets to access parameters and uploaded files from forms submitted with ENCTYPE="multipart/form-data"
See also:
Jason Hunter's code library
http://www.servlets.com/cos/
com.oreilly.servlet.MultipartRequest - has a getParameter method
See also:
http://jakarta.apache.org/commons/sandbox/fileupload/

Similar Messages

UploadBean with JBoss Problem

Dear Experts
I am currently creating a web page which allows the customers to upload csv file.
I serached through the net and found that people are using "UploadBean" for this thus I downloaded the uploadbean jar file and imported it to my Jboss library.
My jsp code is :
<%String uploadDir = "C:/EVS Temp";%>
<jsp:useBean id="upBean" scope="page" class="javazoom.upload.UploadBean" >
<jsp:setProperty name="upBean" property="folderstore" value="<%=uploadDir%>" />
</jsp:useBean>Followed by a save button.
But I got the error message like this:
An error occurred at line: 27 in the jsp file: /meter/meter_uploadMeterList.jsp
javazoom.upload.UploadBean cannot be resolved to a type
26: <%String uploadDir = "C:/EVS Temp"; %>
27: <jsp:useBean id="upBean" scope="page" class="javazoom.upload.UploadBean" >
28: <jsp:setProperty name="upBean" property="folderstore" value="<%=uploadDir%>" />
29: </jsp:useBean>
Stacktrace:
org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:92)
org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:330)
org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:415)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:308)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:286)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:273)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:566)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:316)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:336)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)I understand that this uploadBean problem has been asked many times. But I dont think those answers can solve my problem as they was not using JBoss.
On the Uploadbean Support site, they said uploadbean is not tested with JBoss.
http://www.javazoom.net/jzservlets/uploadbean/documentation/software.html
Any idea for this?
Thanks alot.

Drop your ear into JBOSS_HOME\server\defaultJBOSS_HOME\server\default\deploy that is. Also the webapp must have a context root set up so that you can access it through
http//localhost:8080/myContextRoot/myPage.jsp
The context root is specified in the application descriptor, for instance something like
<!DOCTYPE application PUBLIC '-//Sun Microsystems, Inc.//DTD J2EE Application 1.3//EN' 'http://java.sun.com/dtd/application_1_3.dtd'>
<application>
<display-name>PublicationBase2EAR</display-name>
<description>Application description</description>
<module>
<web>
<web-uri>war-ic.war</web-uri>
<context-root>PubAdmin</context-root>
</web>
</module>
<module>
<ejb>ejb-jar-ic.jar</ejb>
</module>
</application>
Hope this helps,
[email protected]

Problem in uploading a file from JSP to SQL server

Hi,
I am using jspsmart ( www.jspsmart.com)to upload a file in a database.
The problem is that when I am going to download the file and display in the browser, I got the file spoiled by other text on it, in a case of word file I get at the beginning the 'Content-Disposition' and some other strange txt staff, plus my document.
I don't know in what direction investigate.
Thanks in advance
Leonardo

Perhaps you could try anothers components :
UploadBean + Download4J :
http://www.javazoom.net/jzservlets/uploadbean/uploadbean.html
http://www.javazoom.net/jzservlets/download4j/download4j.html

Problem with commons-fileupload library.

Hello,
I'm using the following code to try and upload files to my Tomcat server from HTTP clients. The code is inside a JSP page. When I submit the form to this jsp page, I get no errors but the file is not being uploaded and the only out.println statement that is printing is the first one that tests if the form is multi-part. It prints true.
     boolean isMultipart = FileUpload.isMultipartContent(request);
     out.println("" + isMultipart);
     if (isMultipart) {
          DiskFileUpload upload = new DiskFileUpload();
          upload.setSizeThreshold(2000000);
          upload.setSizeMax(5000000);
          int sizeThresh = 2000000, sizeMax = 5000000;
          String dir = "c:/temp";
          List items = upload.parseRequest(request, sizeThresh, sizeMax, dir);
          Iterator iter = items.iterator();
          while (iter.hasNext()) {
               FileItem item = (FileItem) iter.next();
               out.println(item.getFieldName());
               if (item.isFormField()) {
                    continue;
               else {
                    String fieldName = item.getFieldName();
                    String fileName = item.getName();
                    String contentType = item.getContentType();
                    boolean isInMemory = item.isInMemory();
                    long sizeInBytes = item.getSize();
                    out.println("Info: " + sizeInBytes + " " + contentType + " " + fileName + " " + fieldName);
                    File uploadedFile = new File("test.txt");
                    item.write(uploadedFile);
     } Any idea what my problem is?
Thanks.

Sorry to keep posting but this gets more complex. Here's the deal.
The UploadBean works on both Tomcat 4 and Tomcat 5 as long as the code below has not been called yet for the user's session. It is code that asks the browser for authentication. Once this code has been called for the current session, the Upload Bean no longer works.
Any idea what would cause this?
package com.biscuit.servlets;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
* NTLM authorization (Challenge-Response) test servlet.
* Requires IE on the client side.
* In order to avoid browser log on dialog box User Authentication/Logon
* settings should be set to:
* <ol>
* <li>Automatic logon in Intranet zone or</li>
* <li>Automatic logon with current username and password</li>
* </ol>
* Based on information found on jGuru WEB site:
* http://www.jguru.com/faq/viewquestion.jsp?EID=393110
* @author Leonidius
* @version 1.0 2002/06/17
public class NTLMTest extends HttpServlet{
     // Step 2: Challenge message
     final private static byte[] CHALLENGE_MESSAGE =
          {(byte)'N', (byte)'T', (byte)'L', (byte)'M', (byte)'S', (byte)'S', (byte)'P', 0,
          2, 0, 0, 0, 0, 0, 0, 0,
          40, 0, 0, 0, 1, (byte)130, 0, 0,
          0, 2, 2, 2, 0, 0, 0, 0, // nonce
          0, 0, 0, 0, 0, 0, 0, 0};
     * HTTP request processing
     protected synchronized void service(HttpServletRequest request,
          HttpServletResponse response)
          throws IOException, ServletException{
          PrintWriter out = response.getWriter();
          try{
               String auth = request.getHeader("Authorization");
               if (auth == null) {
                    response.setContentLength(0);
                    response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
                    response.setHeader("WWW-Authenticate", "NTLM");
                    response.flushBuffer();
                    return;
               if (!auth.startsWith("NTLM ")) return;
               byte[] msg = new sun.misc.BASE64Decoder().decodeBuffer(auth.substring(5));
               // Step 1: Negotiation message received
               if (msg[8] == 1) {
                    // Send challenge message (Step 2)
                    response.setContentLength(2);
                    response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
                    response.setHeader("WWW-Authenticate",
                    "NTLM " + new sun.misc.BASE64Encoder().encodeBuffer(CHALLENGE_MESSAGE));
                    out.println(" ");
                    response.flushBuffer();
                    return;
               // Step 3: Authentication message received
               if (msg[8] == 3) {
                    int off = 30;
                    int length, offset;
                    length = (msg[off+1]<<8) + msg[off];
                    offset = (msg[off+3]<<8) + msg[off+2];
                    String domain = new String(msg, offset, length);
                    domain = removeBlanks(domain).toUpperCase();
                    length = (msg[off+9]<<8) + msg[off+8];
                    offset = (msg[off+11]<<8) + msg[off+10];
                    String user = new String(msg, offset, length);
                    user = domain + "\\" + removeBlanks(user).toUpperCase();
                    HttpSession session = request.getSession(true);
                    session.setAttribute("userID", user);
                    String forwardAddress = "home";
                    RequestDispatcher dispatcher = request.getRequestDispatcher(forwardAddress);
                    dispatcher.forward(request, response);
//                    length = (msg[off+17]<<8) + msg[off+16];
//                    offset = (msg[off+19]<<8) + msg[off+18];
//                    String ws = new String(msg, offset, length);
//                    ws = removeBlanks(ws);
//                    response.setContentType("text/html");
//                    out.println("<html>");
//                    out.println("<head>");
//                    out.println("<title>NT User Login Info</title>");
//                    out.println("</head>");
//                    out.println("<body>");
//                    out.println(new java.util.Date() + "<br>");
//                    out.println("Server: " + request.getServerName() + "<br><br>");
//                    out.println("Domain: " + removeBlanks(domain) + "<br>");
//                    out.println("Username: " + removeBlanks(user) + "<br>");
//                    out.println("Workstation: " + removeBlanks(ws) + "<br>");
//                    out.println("</body>");
//                    out.println("</html>");
          catch (Throwable ex){
               ex.printStackTrace();
     }//service
     * Removes non-printable characters from a string
     private synchronized String removeBlanks(String s){
          StringBuffer sb = new StringBuffer();
          for (int i = 0; i < s.length(); i++) {
               char c = s.charAt(i);
               if (c > ' ')
               sb.append(c);
          return sb.toString();
}//class NTLMTest

Problem with HttpUploadBean sample code

Hello,
I need upload files to a database and download files from database. I have some problems and i'm trying the sample in the help "File Upload and Download JavaBean and Class Descriptions" - "The HttpUploadBean".
File UploadBean.html:
<html><body>
<form action="beanUploadExample.jsp" ENCTYPE="multipart/form-data" method=POST>
<br> File to upload: <INPUT TYPE="FILE" NAME="File" SIZE="50" MAXLENGTH="120" >
<br><INPUT TYPE="SUBMIT" NAME="Submit" VALUE="Send"> </form>
</body></html>
File beanUploadExample.jsp:
<%@ page language="java" import="java.util.*, oracle.jsp.webutil.fileaccess.*"
%>
<html><body>
<% String userdir = "fileaccess"; %> // user's part of the upload directory
<jsp:useBean id="upbean"
class="oracle.jsp.webutil.fileaccess.HttpUploadBean" >
<jsp:setProperty name="upbean" property="destination" value="<%= userdir %>"
/>
</jsp:useBean>
<%
upbean.setBaseDir(application, request);
upbean.upload(request);
Enumeration fileNames = upbean.getFileNames();
while (fileNames.hasMoreElements()) { %>
<br><%= (String)fileNames.nextElement() %>
<% } %>
<br>Done!
</body></html>
Content of fileaccess.properties file in directory G:\jdeveloper9i\jdev\mywork\AccessFiles\Upload\public_html\WEB-INF
fileaccess.basedir=G:\jdeveloper9i\jdev\mywork\AccessFiles\Upload\public_html\files
(the directory files has been created)
Interner Explorer (version 5.00.3315.1000) show error 500 (Internal Server Error) after to select the file and click in the buttom "Send"
In Debug mode, to press F8 (Step over) in the line upbean.upload(request); show the error:
"Unable to find source file for package oracle.jsp.runtime, filename httpJsp.java"
I'm trying jDeveloper9i version 9.0.2.829
Any help is welcome
Thanks

Hi,
I will try the HttpUploadBean very soon but haven't test it. Will this article would help : Re: File Upload tag and Bean
Rgds.

Javazoom UploadBean - using UploadBean properties within jsp tags

I am working on a jsp web application and integrating the UploadBean from javazoom.net into it. I am using a MySQL database to capture all informaion about mp3 files being uploaded - filename, date, filetype, etc.
Can someone guide me as to whether it is possible to reference the properties of the UploadFile class within a jsp tag?
What I am trying to do is this - I want to capture the filename of the file I upload and store it in a MySQL database. Within the SimpleUpload.jsp page, the filename is accessed within scriplet code as follows:
file.getFileName();
(Where file is a variable representing an instance of the UploadFile class, and getFileName() is a method in this class that returns the file name you are uploading).
What I would like to do is use this method so that this same filename can be used in a a sql:update tag to populate a database with the filename and with the other details of the file which is uploaded.
Can anyone advise as to if this is possible and how? I tried to create a sql:update statement to populate the database with the result of file.getFileName();
The problem is that the sql:update jsp tag can't see the file.getFileName() object and method - it doesn't know about this object and method.
Thanks!

I'd still appreciate an answer to this if anyone can help.
Thanks.

Another selectOneMenu Problem....

Hi all,
first of all I have to say that I'm really new to JSF (just to let you know, that this question might be really stupid...)
Ok, following combination:
-jsp site with a form and the following selectOneMenu:
<h:selectOneMenu id="fileType" value='#{uploadBean.filetype}'>
<f:selectItems value="#{uploadBean.allFiletypes}" />
</h:selectOneMenu>
- uploadBean (code extract):
    String filetype;
    ArrayList allFiletypes;
    public String getFiletype()
        return filetype;
    public void setFiletype(String s)
        filetype = s;
    public Collection getAllFiletypes()
        if(this.allFiletypes==null)
             allFiletypes = new ArrayList();
             allFiletypes.add(new SelectItem("type1"));
             allFiletypes.add(new SelectItem("type2"));
             allFiletypes.add(new SelectItem("type3"));
        return allFiletypes;
    public void setAllFiletypes(Collection list)
        allFiletypes = new ArrayList(list);
    }I can see the select menu filled with the items "type1" .. "type3", but when I selected one type and submitted my form, the filetype is <b>null</b>.
I tried quite a few things and also read quite a few topics in the forum, but either I'm just too stupid to understand them or ... I don't know.
Hopefully one of you has pity with me and has a small look over my problem.
I would be really thankful (as I was trying to solve this problem for nearly the whole day today and as I'm quite sure, it's a stupid mistake ;-) ).
Thanks in advance and greetings!
Steffi

OK, these are my codes:
sample.jsp:
<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
    <%@ page contentType="text/html;charset=shift_jis" %>
    <%@ taglib uri="http://java.sun.com/jsf/html" prefix="h" %>
    <%@ taglib uri="http://java.sun.com/jsf/core" prefix="f" %>
<head>
</head>
<body>
<f:view>
<h:form id="mySampleForm">
<h:selectOneMenu id="fileType" value="#{myMenuBean.filetype}">
     <f:selectItems value="#{myMenuBean.allFiletypes}" />
</h:selectOneMenu>
<h:commandButton type="submit" value="calc" action="ok" />
</h:form>
<HR>
<h:outputText value="#{myMenuBean.filetype}"/>
<HR>
<h:messages />
</f:view>
</body>
</html>
faces-config.xml:
<faces-config>
     <managed-bean>
          <managed-bean-name>myMenuBean</managed-bean-name>
          <managed-bean-class>MyMenuSample</managed-bean-class>
          <managed-bean-scope>session</managed-bean-scope>
     </managed-bean>
</faces-config>
MyMenuSample.java:
import java.util.ArrayList;
import java.util.Collection;
import javax.faces.model.SelectItem;
public class MyMenuSample {
    private String filetype;
    private ArrayList allFiletypes;
    public String getFiletype()
        return filetype;
    public void setFiletype(String s)
        filetype = s;
    public Collection getAllFiletypes()
        if(this.allFiletypes==null)
             allFiletypes = new ArrayList();
             allFiletypes.add(new SelectItem("type1"));
             allFiletypes.add(new SelectItem("type2"));
             allFiletypes.add(new SelectItem("type3"));
        return allFiletypes;
    public void setAllFiletypes(Collection list)
        allFiletypes = new ArrayList(list);
}

Problem while uploading the file page is not forwarding

Hi,
Please tell me the solution for this.
I'm uploading the file, i'm getting the values very thing, but the page is not forwarding what happening i don't no.
Here is the code.
<HTML>
<%@ page language="java" import="javazoom.upload.*,java.util.*" %>
<%@ page errorPage="ExceptionHandler.jsp" %>
<HEAD>
<BODY style="font:'Bookman Old Style' size="3"">
<jsp:useBean id="upBean" scope="page" class="javazoom.upload.UploadBean" >
</jsp:useBean>
<%
// Uploading file code
if (MultipartFormDataRequest.isMultipartFormData(request))
// Uses MultipartFormDataRequest to parse the HTTP request.
     MultipartFormDataRequest mrequest = new MultipartFormDataRequest(request);
String todo = null;
     if (mrequest != null) todo = mrequest.getParameter("todo");
     if ( (todo != null) && (todo.equalsIgnoreCase("upload")) )
                    Hashtable files = mrequest.getFiles();
     UploadFile file = (UploadFile) files.get("uploadfile");
          if ((file != null) && (file.getFileSize() <= 82000))
                    {System.out.println("<li>Form field : uploadfile"+"<BR> Uploaded file : "+file.getFileName()+" ("+file.getFileSize()+" bytes)"+"<BR> Content Type : "+file.getContentType());
                // Uses the bean now to store specified by jsp:setProperty at the top.
                    upBean.store(mrequest, "uploadfile");
                    else
                    System.out.println("Not Uploaded");
if (mrequest != null)
     String Schoolname= mrequest.getParameter("schoolname");
     session.setAttribute("saSchoolname", Schoolname);
System.out.println("Schoolname     "+Schoolname);
%>
                    <jsp:forward page="FileTransfer.jsp"/>
<%
     else out.println("<BR> todo="+todo);
//System.out.println(session.getAttribute("saswrite"));
String amessage = request.getParameter("passmsg");
%>
<form name='subregiform' method="POST" onsubmit='return checkForm()' action ="FileSubmit2.jsp" ENCTYPE="multipart/form-data">
<table width="491" border="0" cellpadding="2" >
<tr>
<td width="171" align="right"><br> S.S.C  :</td>
<td width="103" align="center">Institution Name
     <input type="text" name="schoolname" size = 12 maxlength = 35 value = <%
          if(session.getAttribute("saSchoolname")!= null){%>
     <%=session.getAttribute("saSchoolname")%><%}%>>     </td>
<tr><td width="165"><div align="right">Upload Resume :<br> <br> <br></div></td>
<td width="356"><input type="file" name="uploadfile" size = 20>
<font size=1><br>    <I>(Only .doc,.rtf,.txt,.html)</I></font><BR>
   <% if (amessage !=null){ %><FONT SIZE="" COLOR="RED"><strong><%= amessage %></strong></FONT><% }%> </td>
</tr>
<tr>
<td colspan="2">
<p align="center">
     <input type="hidden" name="todo" value="upload">
<input type="submit" name="Submit" value="Submit">
     </p>
</td>
</tr>
</table>
</form>
</BODY>
</HTML>

This code is a mess! Don't put your logic and control into your JSP; use the JSP only for display!
As for your error, it's because you can't forward after the response has been committed. An illegal state exception will be thrown except you can't see it in the browser because the server has already committed the response and can't change it now. You need to get rid of the forward action. Put in a link to that page instead. Or use a a meta tag to redirect.
But really, this code cannot be modified to get rid of the problem. It should be scrapped and you should rethink your design. Have a servlet do your control and all this uploading code should also be put into a servlet; never in a JSP
People on the forum help others voluntarily, it's not their job.
Help them help you.
Learn how to ask questions first: http://faq.javaranch.com/java/HowToAskQuestionsOnJavaRanch
(Yes I know it's on JavaRanch but I think it applies everywhere)
Edited by: nogoodatcoding on Oct 5, 2007 2:56 PM

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

Problem with Threads and "plase wait..."-Window

Hi everyone,
I have a problem that I'm not able to solve in any way... I have a time-consuming task (a file decryption) which I execute in a separate thread; I've used the SwingWorker class, like suggested by sun-tutorial, and it works right. The problem is that I have to wait that the decryption have finished before continuing with program-execution. Therefore I would like to display a "please wait"-window while the task runs. I've tryed all the possible ways I know but the problem is always the same: the waitWindow is displayed empty, the bounds are painted but the contents no; it's only painted when the decrypt-task has finished. Please help me, I have no more resources....
decrypt-file code:
public class DecryptFile {
private String cryptedFileNameAndPath;
private ByteArrayInputStream resultStream = null;
// need for progress
private int lengthOfTask;
private int current = -1;
private String statMessage;
public DecryptFile(String encZipFileNameAndPath) {
    cryptedFileNameAndPath = encZipFileNameAndPath;
    //Compute length of task...
    // 0 for indeterminate
    lengthOfTask = 0;
public ByteArrayInputStream getDecryptedInputStream() {
    return this.resultStream;
   * Called from ProgressBarDemo to start the task.
public void go() {
    current = -1;
    final SwingWorker worker = new SwingWorker() {
      public Object construct() {
        return new ActualTask();
    worker.start();
   * Called from ProgressBarDemo to find out how much work needs
   * to be done.
public int getLengthOfTask() {
    return lengthOfTask;
   * Called from ProgressBarDemo to find out how much has been done.
public int getCurrent() {
    return current;
public void stop() {
    current = lengthOfTask;
   * Called from ProgressBarDemo to find out if the task has completed.
public boolean done() {
    if (current >= lengthOfTask)
      return true;
    else
      return false;
public String getMessage() {
    return statMessage;
   * The actual long running task. This runs in a SwingWorker thread.
class ActualTask {
    ActualTask () {
      current = -1;
      statMessage = "";
      resultStream = AIUtil.getInputStreamFromEncZip(cryptedFileNameAndPath); //here the decryption happens
      current = 0;
      statMessage = "";
}The code that calls decryption and displays waitWindow
      final WaitSplash wS = new WaitSplash("Please wait...");
      final DecryptFile cryptedTemplate = new DecryptFile (this.templateFile);
      cryptedTemplate.go();
      while (! cryptedTemplate.done()) {
        try {
          wait();
        } catch (Exception e) { }
      this.templateInputStream = cryptedTemplate.getDecryptedInputStream();
      wS.close();Thanks, thanks, thanks in advance!
Edoardo

Maybe you can try setting the priority of the long-running thread to be lower? so that the UI will be more responsive...

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