Innerjoin problem.

Hello,
For my website I use "dynamic" menu's which are stored in a
SQL table. When a certain product is shown on the detail page the
menu according to the product categorie (dutch for category) is
shown.
The products themselves and all their information are stored
in the 'product' table, the menu's for the different product
categories are stored in the 'index' table.
On the detail page a get is used to show the right product
information. I wanted to do the same thing for the menu and came up
with this SQL:
SELECT product_2.*
FROM (product INNER JOIN index ON product.categorie =
index.categorie) INNER JOIN product AS product_2 ON index.index =
product_2.categorie
WHERE product.slug = colname2
Table fields used:
product.categorie
product.slug (this is the name of the product which is used
in the GET to show the right product)
index.categorie (this variable is the same as the product
table counterpart. When a product category "hat" exists, there is
also a "hat" row in the index table)
index.index (this is where the HTML of the actual menu is
stored)
When I show it like this the following error pops up:
You have an error in your SQL syntax; check the manual that
corresponds to your MySQL server version for the right syntax to
use near 'index ON product.categorie = index.categorie) INNER JOIN
product AS product_2 ON' at line 1
I kind of copied and renamed the variables which worked for
an older website of mine (didnt write it myself, dont have that
much knowledge of SQL/PHP), this code works when used to show
comparable products, instead of the "categorie" variable an "id"
variable is used which is a short number.
I cant figure out what's going wrong, maybe u guyz can tell
me. If you need any additional information please let me know.
Thanks!

SyKeSnr1 posted in macromedia.dreamweaver:
> Can anyone tell me if this has to do with faulty SQL, or
is it
> simply not possible to do an innerjoin with two
non-number
> variables or something? I cant figure out why this isnt
working..
I'm not much good with JOINs for some reason.
If you don't get an answer in here, then, if you have access
to a
Usenet NewsServer, there are newsgroups that are devoted to
databases
and SQL
comp.databases.mysql
alt.php.sql
and probably more. You'll need to mention which database
you're using.
Mark A. Boyd
Keep-On-Learnin' :)

Similar Messages

Problem with a query inner-join

Hello;
I'm trying to innerjoin these 2 tables in my query for a page that will allow you to add / edit records. Right now, it's telling me I have a data mismatch. I don't see where I went wrong. Can someone help me out?
This is my code:
<cfparam name="url.CategoryID" type="integer" default="0">
<cfparam name="subID" type="integer" default="#url.CategoryID#">
<cfparam name="subName" default="">
<cfparam name="CategoryID" default="">
<cfparam name="Name" default="">
<cfif url.CategoryID GT 0>
<cfquery name="categRec" dataSource="#APPLICATION.dataSource#">
SELECT merchSubCat.subName, merchSubCat.subID, Categories.CategoryID, Categories.Name
FROM merchSubCat
INNER JOIN Categories
 ON merchSubCat.CategoryID = Categories.CategoryID
WHERE merchSubCat.subID = <cfqueryparam value="#url.CategoryID#" cfsqltype="cf_sql_integer">
</cfquery>

<cfif categRec.RecordCount EQ 1>
<cfset CategoryID = categRec.subID>
<cfset subName = categRec.subName>
<cfset CategoryID = categRec.CategoryID>
<cfset Name = categRec.Name>
</cfif>
</cfif>
this is my error:
Error Executing Database Query.
[Macromedia][SequeLink JDBC Driver][ODBC Socket][Microsoft][ODBC Microsoft Access Driver] Type mismatch in expression.
The error occurred in C:\Websites\187914kg3\admin\cms\merchant\merchSub-edit.cfm: line 16
14 : INNER JOIN Categories
15 : ON merchSubCat.CategoryID = Categories.CategoryID
16 : WHERE merchSubCat.subID = <cfqueryparam value="#url.CategoryID#" cfsqltype="cf_sql_integer">
17 : </cfquery>
18 :
I don't see what I did wrong, can another pair of eyes see where I missed something?
Thank you

I changed it to number, and it works now.
I have one other problem.. I'm trying to use a drop down menu in this form to edit a record. I want the drop down to show what is being used in the database when you go to edit a record. It runs on one query, to populate the select, but it pulls info from another and this isn't working. Actually, it's the innerjoin I just made.. can you help me?

<cfquery name="catList" datasource="#APPLICATION.dataSource#">
SELECT DISTINCT merchCategory.CategoryID, merchCategory.CatName AS cat_name
FROM merchCategory
ORDER BY CatName
</cfquery>
<cfselect enabled="No" name="CategoryID" size="1" class="smallText" multiple="no" query="catList" value="CategoryID" display="cat_name" queryPosition="below" selected="#categRec.Name#">
 <option value="">--Select a Category--</option>
 </cfselect>
As you see, in the selected part of the tag, I'm trying to pull info from the other query we just fixed. I know this is wrong, how do I do this?

Problem in Select Statment

I have two tables
TAB1
F1 F2
A1 AA
A2 AA
A3 BB
A4 AA
A5 AA
TAB2
F1 F2 F3
B1 AA D1
B2 BB D1
B3 CC D1
B4 AA D2
B5 AA D3
B6 BB D1
B7 AA D1
B8 DD D1
I use following statement
Select F1 from TAB1 where TAB1.F2 in (Select F2 from TAB2)
Its working properly with my requirement.
My problem is now I want to get field F1 in TAB2 also. How can I get this?
Finally I needed result is
TAB1-F1 TAB2-F1
A1 B1
A2 B1
A3 B2
A4 B1
A5 B1
Basically I want, when TAB1-F2 data in TAB2-F2 field I want get TAB2-F1 field also.

hi Nelson.
Syntax
... [(] {dbtab_left [AS tabalias_left]} | join
{[INNER] JOIN}|{LEFT [OUTER] JOIN}
{dbtab_right [AS tabalias_right] ON join_cond} [)] ... .
Effect
The join syntax represents a recursively nestable join expression. A join expression consists of a left-hand and a right- hand side, which are joined either by means of [INNER] JOIN or LEFT [OUTER] JOIN . Depending on the type of join, a join expression can be either an inner ( INNER) or an outer (LEFT OUTER) join. Every join expression can be enclosed in round brackets. If a join expression is used, the SELECT command circumvents SAP buffering.
On the left-hand side, either a single database table, a view dbtab_left, or a join expression join can be specified. On the right-hand side, a single database table or a view dbtab_right as well as join conditions join_cond can be specified after ON. In this way, a maximum of 24 join expressions that join 25 database tables or views with each other can be specified after FROM.
AS can be used to specify an alternative table name tabalias for each of the specified database table names or for every view. A database table or a view can occur multiple times within a join expression and, in this case, have various alternative names.
The syntax of the join conditions join_cond is the same as that of the sql_cond conditions after the addition WHERE, with the following differences:
At least one comparison must be specified after ON.
Individual comparisons may be joined using AND only.
All comparisons must contain a column in the database table or the view dbtab_right on the right-hand side as an operand.
The following language elements may not be used: BETWEEN, LIKE, IN.
No sub-queries may be used.
For outer joins, only equality comparisons (=, EQ) are possible.
If an outer join occurs after FROM, the join condition of every join expression must contain at least one comparison between columns on the left-hand and the right-hand side.
In outer joins, all comparisons that contain columns as operands in the database table or the view dbtab_right on the right-hand side must be specified in the corresponding join condition. In the WHERE condition of the same SELECT command, these columns are not allowed as operands.
Resulting set for inner join
The inner join joins the columns of every selected line on the left- hand side with the columns of all lines on the right-hand side that jointly fulfil the join_cond condition. A line in the resulting set is created for every such line on the right-hand side. The content of the column on the left-hand side may be duplicated in this case. If none of the lines on the right-hand side fulfils the join_cond condition, no line is created in the resulting set.
Resulting set for outer join
The outer join basically creates the same resulting set as the inner join, with the difference that at least one line is created in the resulting set for every selected line on the left-hand side, even if no line on the right-hand side fulfils the join_cond condition. The columns on the right-hand side that do not fulfil the join_cond condition are filled with null values.
Example
Join the columns carrname, connid, fldate of the database tables scarr, spfli and sflight by means of two inner joins. A list is created of the flights from p_cityfr to p_cityto. Alternative names are used for every table.
PARAMETERS: p_cityfr TYPE spfli-cityfrom,
p_cityto TYPE spfli-cityto.
DATA: BEGIN OF wa,
fldate TYPE sflight-fldate,
carrname TYPE scarr-carrname,
connid TYPE spfli-connid,
END OF wa.
DATA itab LIKE SORTED TABLE OF wa
WITH UNIQUE KEY fldate carrname connid.
SELECT ccarrname pconnid f~fldate
INTO CORRESPONDING FIELDS OF TABLE itab
FROM ( ( scarr AS c
INNER JOIN spfli AS p ON pcarrid = ccarrid
AND p~cityfrom = p_cityfr
AND p~cityto = p_cityto )
INNER JOIN sflight AS f ON fcarrid = pcarrid
AND fconnid = pconnid ).
LOOP AT itab INTO wa.
WRITE: / wa-fldate, wa-carrname, wa-connid.
ENDLOOP.
Example
Join the columns carrid, carrname and connid of the database tables scarr and spfli using an outer join. The column connid is set to the null value for all flights that do not fly from p_cityfr. This null value is then converted to the appropriate initial value when it is transferred to the assigned data object. The LOOP returns all airlines that do not fly from p_cityfr.
PARAMETERS p_cityfr TYPE spfli-cityfrom.
DATA: BEGIN OF wa,
carrid TYPE scarr-carrid,
carrname TYPE scarr-carrname,
connid TYPE spfli-connid,
END OF wa,
itab LIKE SORTED TABLE OF wa
WITH NON-UNIQUE KEY carrid.
SELECT scarrid scarrname p~connid
INTO CORRESPONDING FIELDS OF TABLE itab
FROM scarr AS s
LEFT OUTER JOIN spfli AS p ON scarrid = pcarrid
AND p~cityfrom = p_cityfr.
LOOP AT itab INTO wa.
IF wa-connid = '0000'.
WRITE: / wa-carrid, wa-carrname.
ENDIF.
ENDLOOP.
we r using 2 type of joins in abap they are
1) inner join.
this will join 2 tables using an common fiend and return the result with field values wich are common in both the tables
itab1 itab2
a b c a d
1 2 3 1 5
2 3 4 3 6
after innerjoining itab1 n itab2 on field a we wil get the o/p as
a b c d
1 2 3 5
only common field is taken..
2)left outer join
here it wil work in opossite way it will give values whic are not common
itab1 itab2
a b c a d
1 2 3 1 5
2 3 4 3 6
after left outer joining itab1 n itab2 on field a we wil get the o/p as
a b c d
2 3 4
only fields which are not common is taken from the left table..other field(d here) wil be empty
I think it will help u.
Reward Points if helpful.
regards,
Amber s

Problem with a multisourced dimension

Hi Guru's
I have a problem with a multisourced dimension. Some of the values that are in the tables are not visible when I create a filter and choose all choices, but when facts are set against the dimension these values do show.
This is the situation: In my physical layer I've got 3 tables that are all pretty similar, structure is like year, quarter, amount. From these three tables I create 3 fact tables and 1 dimension, where the dimension is YearQuarter with two columns (year and quarter) and 3 sources. One of these tables has a quarter 0 (zero). The DimYearQuarter table is innerjoined in the BMM wit all 3 facttables. Changing to right or left outer doesn't change the results.
In answers when i create a report just with the dimension columns , quarter 0 is not visible. When the measure (where the quarter 0 associated to) is added to my request it shows the values for quarter 0. When applying a filter, the quarter 0 is not visible with "all choices", but a filtercondition works with Quarter is equal to 0.
Any suggestions are kindly appreciated. If more info is needed, I'm very willing to provide.
I'm on 10.1.3.4.1 on windows server 2003 (server side) and XP professional as a client.
Kind regards,
Gilles

You should alias the physical tables such that you can then physically join the aliases one to another. Then you should be able to use the dimension table on it's own - for prompting purposes and such.
(Aliasing of physical tables is an OBI best practice)

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...

Problem with threads in j2me

im using jdk 1.6 with java wtk 2.1
ya i know..
2.1 is a jdk1.4 source
but im using souce as 1.4 during compiliation so thats not the prob
this is my code
package org.learn;
import javax.microedition.midlet.MIDlet;
import javax.microedition.lcdui.Alert;
import javax.microedition.lcdui.Display;
public class thtest extends MIDlet
Thread t;
public void startApp()
Alert a=new Alert("hello");
a.setString("hello");
Alert b=new Alert("world");
b.setString("world");
Display d = Display.getDisplay(this );
d.setCurrent(a);
t=Thread.currentThread();
try{
t.sleep(10000);
catch (Exception e){}
d.setCurrent(b);
public void pauseApp()
public void destroyApp(boolean unconditional)
its just supposed to pause between the alerts using threads
however when i run it using the wtk, the emulator run properly but when i launch the app, it stops executing giving me this:
"Error verifying method org/learn/thtest startApp()V
Approximate bytecode offset 49: Inconsistent or missing stackmap at target
%the stack info%
Execution completed.
437782 bytecodes executed
9 thread switches
486 classes in the system (including system classes)
2506 dynamic objects allocated (73832 bytes)
2 garbage collections (60652 bytes collected)
Execution completed.
437782 bytecodes executed
9 thread switches
486 classes in the system (including system classes)
ALERT: java/lang/VerifyError: org/learn/thtest.
2506 dynamic objects allocated (73832 bytes)
2 garbage collections (60652 bytes collected)
please can someone help me out with this, is it an error on my part or do i have to set some option.

Hi gandalf123,
First, Thread.sleep is a static method, so you don't need to create a Thread object to use it.
I think the problem is due to the fact you don't preverify your midlet.
More over, you don't need to double post your question.

Problem with threads and camera.

Hi everybody!
I've a problem with taking snapshot.
I would like to display a loading screen after it take snapshot ( sometimes i
have to wait few seconds after i took snapshot. Propably photo is being taken in time where i have to wait).
I was trying to use threads but i didn't succeed.
I made this code:
display.setCurrent(perform);
        new Thread(new Runnable(){
            public void run() {
                while((!performing.isShown()) && (backgroundCamera.isShown())){
                    Thread.yield();
                notifyAll();
        }).start();
        new Thread(new Runnable(){
            public void run() {
                try {
                    this.wait();
                } catch(Exception e) {
                    exceptionHandler(e);
                photo = camera.snapshot();
                display.setCurrent(displayPhoto);
        }).start();This code is sometimes showing performing screen but sometimes no.
I don't know why. In my opinion performing.isShown() method isn't working correctly.
Does anyone have some idea how to use threads here?

Hi,
I've finally managed to work this fine.
The code:
       Object o = new Object();
       display.setCurrent(perform);
        new Thread(new Runnable(){
            public void run() {
                while(!performing.isShown()){
                    Thread.yield();
               synchronized(o) {
                  o.notify();
        }).start();
        new Thread(new Runnable(){
            public void run() {
                try {
                    synchronized(o) {
                       o.wait(1);
                } catch(Exception e) {
                    exceptionHandler(e);
                photo = camera.snapshot();
                display.setCurrent(displayPhoto);
        }).start();

Problem with threads and graphics

I have a thread that chooses paths for a Travelling salesman problem, it then calls a TSPdraw class and passes it the path, which the class then draws. the problem is when i have two threads it creates two windows but only draws a path in one of them. any ideas where i`m going wrong

Are you using swing components? Swing isn't threadsafe. If you have multiple threads that want to update your UI you need to use the SwingUtilities.invokeLater(...)or invokeAndWait(...). There is a page in the swing tutorial about this at: http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html

Problem with threads hanging

We have a problem where our application stops responding after a few days of usage. Things will for fine for a day or two, and then pretty quickly threads will start getting hung up, usually in places where they are allocating memory
We are running WebLogic 8.1 SP2 on Sun JDK 1.4.2_04 on Solaris 8 using the alternate threading model and the -server hotspot vm. We are running pretty much the same code that we had no problems with under WebLogic 6.1 SP4 and Sun JDK 1.3.1.
A thread dump usually shows that some or all of our execute threads are in the state "waiting for monitor entry" even though they are not currently waiting on any java locks. Here is a sample thread from the thread dump (we have ~120 threads so I don't want to post the full dump).
=============================================================================================
"ExecuteThread: '8' for queue: 'itgCrmWarExecutionQueue'" daemon prio=5 tid=0x005941d0 nid=0x2c waiting for monitor entry [c807f000..c807fc28]
at java.lang.String.substring(String.java:1446)
at java.lang.String.substring(String.java:1411)
at weblogic.servlet.internal.ServletRequestImpl.getRelativeUri(ServletRequestImpl.java:1872)
at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:3492)
at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2585)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:197)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:170)
=============================================================================================
String.java line 1446 for this jdk allocates a new String object, and all the other threads in this state also are creating new objects or arrays, etc.
We've done a pstack on this process when it's in this state, and the threads that are in the "waiting for monitor entry" that look like they're allocating memory are all waiting on the same lwp_mutex_lock with some allocation method that's calling into the native TwoGenerationCollectorPolicy.mem_allocate_work (see pstack output below for the same thread as in the thread dump above)
=============================================================================================
----------------- lwp# 44 / thread# 44 --------------------
ff31f364 lwp_mutex_lock (e3d70)
fee92384 __1cNObjectMonitorGenter26MpnGThread__v_ (5000, 525c, 5000, 50dc, 4800, 4af0) + 2d8
fee324d4 __1cSObjectSynchronizerKfast_enter6FnGHandle_pnJBasicLock_pnGThread__v_ (c807f65c, c807f7d4, 5941d0, 0, 35d654, fee328ec) + 68
fee32954 __1cQinstanceRefKlassZacquire_pending_list_lock6FpnJBasicLock__v_ (c807f7d4, ff170000, d4680000, 4491d4, fee1bc2c,
0) + 78
fee3167c __1cPVM_GC_OperationNdoit_prologue6M_i_ (c807f7bc, 4400, ff170000, 2d2b8, 4a6268, c807fa18) + 38
fee2e0b0 __1cIVMThreadHexecute6FpnMVM_Operation__v_ (c807f7bc, 963a8, 0, 0, 1, 0) + 90
fed2c2a4 __1cbCTwoGenerationCollectorPolicyRmem_allocate_work6MIii_pnIHeapWord__ (962c0, ff1c29ec, ff1c297c, ff131a26, 4800, 4998) + 160
fed22940 __1cNinstanceKlassRallocate_instance6MpnGThread__pnPinstanceOopDesc__ (ee009020, 5941d0, 15ca581, 3647f0, 4a6268, c807f8c8) + 180
fed34928 __1cLOptoRuntimeFnew_C6FpnMklassOopDesc_pnKJavaThread__v_ (ee009018, 5941d0, 0, 0, 0, 0) + 28
fa435a58 ???????? (ee009018, e86de, 15ca4de, 50dc, 5941d0, c807f9c8)
fb36f9a4 ???????? (0, d412ccd8, ee046c28, ff170000, 0, 0)
fad8b278 ???????? (ee046c28, d6000c90, ee046530, 8, db8e8450, c807f9e8)
fad62abc ???????? (d412ccd8, ee046530, d6000c90, ee3bfa38, 8, c807fa18)
fa4b3c38 ???????? (c807fb9c, 0, f2134700, fa415e50, 8, c807faa8)
fa40010c ???????? (c807fc28, c807fe90, a, ee9e1e20, 4, c807fb40)
fed5d48c __1cJJavaCallsLcall_helper6FpnJJavaValue_pnMmethodHandle_pnRJavaCallArguments_pnGThread__v_ (c807fe88, c807fcf0, c807fda8, 5941d0, 5941d0, c807fd00) + 27c
fee4b784 __1cJJavaCallsMcall_virtual6FpnJJavaValue_nLKlassHandle_nMsymbolHandle_4pnRJavaCallArguments_pnGThread__v_ (ff170000, 594778, c807fd9c, c807fd98, c807fda8, 5941d0) + 164
fee5e8dc __1cJJavaCallsMcall_virtual6FpnJJavaValue_nGHandle_nLKlassHandle_nMsymbolHandle_5pnGThread__v_ (c807fe88, c807fe84, c807fe7c, c807fe74, c807fe6c, 5941d0) + 6c
fee6fc74 __1cMthread_entry6FpnKJavaThread_pnGThread__v_ (5941d0, 5941d0, 838588, 594778, 306d10, fee69254) + 128
fee6927c __1cKJavaThreadDrun6M_v_ (5941d0, 2c, 40, 0, 40, 0) + 284
fee6575c _start   (5941d0, fa1a1600, 0, 0, 0, 0) + 134
ff3758c0 lwpstart (0, 0, 0, 0, 0, 0)
=============================================================================================
Also when it's having this problem, the "VM Thread" is always using a lot of processor time. We did a couple of pstacks today while it was having this problem, and this thread was stuck in the ONMethodSweeper.sweep for over 15 minutes when we finally killed the server.
From the thread dump:
"VM Thread" prio=5 tid=0x000e2d20 nid=0x2 runnable
From the first pstack:
=============================================================================================
----------------- lwp# 2 / thread# 2 --------------------
fed40c04 __1cXvirtual_call_RelocationIparse_ic6FrpnICodeBlob_rpC5rppnHoopDesc_pi_nNRelocIterator__ (42a2f4, fa5fa46d, ffffffff, fc4ffcb8, 42a2f4, 42a324) + 124
fed46318 __1cKCompiledIC2t5B6MpnKRelocation__v_ (42a2f0, fc4ffd24, fc4ffd4c, e802, 0, 6) + 38
fed90c38 __1cHnmethodVcleanup_inline_caches6M_v_ (fa5f7f88, fa608940, 1, 0, fa400000, 6) + 1ac
fede18b4 __1cONMethodSweeperFsweep6F_v_ (2cf38, 0, ffffffff, ff1cf1fc, ff1c66e8, fede1d44) + 1b0
fede1e6c __1cUSafepointSynchronizeFbegin6F_v_ (2cf38, ff1ba138, 5000, 50dc, 5000, 525c) + 248
feef1fd4 __1cIVMThreadEloop6M_v_ (4400, 4000, 4324, 4000, 42b0, 3800) + 3d4
feef1ae4 __1cIVMThreadDrun6M_v_ (e2d20, 2, 40, 0, 40, 0) + 8c
fee6575c _start   (e2d20, ff270200, 0, 0, 0, 0) + 134
ff3758c0 lwpstart (0, 0, 0, 0, 0, 0)
=============================================================================================
Second pstack
=============================================================================================
----------------- lwp# 2 / thread# 2 --------------------
fed41180 __1cXvirtual_call_RelocationIparse_ic6FrpnICodeBlob_rpC5rppnHoopDesc_pi_nNRelocIterator__ (0, ff1b9664, ffffffff, fc4ffcb8, a6f2cc, fc4ffbd0) + 6a0
fed46318 __1cKCompiledIC2t5B6MpnKRelocation__v_ (a6f2c8, fc4ffd24, fc4ffd4c, e802, 0, 6) + 38
fed90c38 __1cHnmethodVcleanup_inline_caches6M_v_ (faded4c8, fadf2c80, 1, 0, fa400000, 6) + 1ac
fede18b4 __1cONMethodSweeperFsweep6F_v_ (2cf38, 0, ffffffff, ff1cf1fc, ff1c66e8, fede1d44) + 1b0
fede1e6c __1cUSafepointSynchronizeFbegin6F_v_ (2cf38, ff1ba138, 5000, 50dc, 5000, 525c) + 248
feef1fd4 __1cIVMThreadEloop6M_v_ (4400, 4000, 4324, 4000, 42b0, 3800) + 3d4
feef1ae4 __1cIVMThreadDrun6M_v_ (e2d20, 2, 40, 0, 40, 0) + 8c
fee6575c _start   (e2d20, ff270200, 0, 0, 0, 0) + 134
ff3758c0 lwpstart (0, 0, 0, 0, 0, 0)
=============================================================================================
Has anyone ever seen anything like this? I'm trying to figure out if this is caused by something we're doing, or something relating to our environment and jvm options. Any ideas?

Thanks for the reply - I'm testing our app with the +UseConcMarkSweepGC now in our test environment to make sure it doesn't cause any problems there. Unfortunately the only place we've had this problem is on the production server, so it's extra difficult debugging this.
We're using the following memory options:
-ms512m -mx512m -XX:NewSize=128m -XX:PermSize=192m -XX:MaxNewSize=128m -XX:MaxPermSize=192m -XX:SurvivorRatio=8and the following debugging options, as we've also been seeing OutOfMemoryErrors ( see http://forum.java.sun.com/thread.jsp?forum=37&thread=522354&tstart=45&trange=15 )
-verbosegc -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintHeapAtGCBTW, which c++filt version and options are you using? Our Solaris boxes only seem to have the GNU version installed. I was trying to run that on some of the other stack traces and wasn't getting anywhere, and didn't know if because it was GNU version wouldn't work on something compiled with the Sun compiler.
Thanks!
--Andy

Innerjoin problem.

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