Thread's run() doesn't get called ?

Hi,
I have a subclass of Thread and I create its instance and call its start() method. Documenttion on Sun's site says that start tells JVM to call run() method....BUT the problem is the run() method is not called as soon as I call start() Why ?
For Example
void foo()
(new MyThread()).start();
System.out.Println("RUN NOT CALLED YET");
class MyThread extends thread {
public void run()
System.out.Println("RUN CALLED");
So here "RUN NOT CALLED YET" is printed before "RUN CALLED" gets printed. Why ? Any clue ?

Hi,
That is how threading work. A new thread is created and scheduled for execution, but it's not certain that it will start execution before the main threads println statement is executed. (Remember that the threads will (logically) be executing in parallell)
/Kaj

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Validator doesn't get called if textField is null

Has anybody seen this? Is there a workaround?
Thanks!

Hi,
The validator will not be invoked for fields in which no value has been entered.
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In case the the custom validator does some other validation then it does not make sense to call the validator if there is no value in the field. The practice was to check if the value is null before proceeding to the validation. The same can be achieved by using the required property. As the required property would enfore entering of a value, the custom validator would have a value to validate.
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H:dataTable getter called during APPLY_REQUES_VALUES stage

Hello,
I'm having some trouble with localization. I need to set labels of components in an h:dataTable with localized strings.
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I dug through the code a bit...
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at javax.faces.component.UIData.getValue(UIData.java:527)
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JComboBox itemStateChanged gets called twice.

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sanokistoka wrote:
jschell wrote:
sanokistoka wrote:
Let me ask the last question in a better way: Does anyone have any GOOD ideas?Get back to us when you have found your good solution.Stop wasting bandwidth. I didn't post here to be a smart ars like you and pretend that I have a solution to a rare problem... FYI - the workaround is to use the tomcat lifecycle events (AFTER_STOP_EVENT) to achieve the same - why do you think I mentioned it's a tomcat listener in the first place? Feel free to educate me.
So you are claiming that Runtime.getRuntime().addShutdownHook() that you posted in the above is not part of the java API?
Or perhaps that everything that is added via addShutdownHook() runs?
Surely you are not claiming that it isn't calling addShutdownHook() in the first place?
Get a life and a job.I have both but thanks for the concern.
sanokistoka wrote:
swamyv wrote:
There are free tools available to debug windows. I think gdb is one of them. If you search you can find some good tools.
If you find any good tools that you like share it with us.
Yes I will try gdb (have cygwin) and see where this takes us - not sure if the JVM or tomcat6.exe have the symbols to get a meaningful stack trace. As luck would have it, [https://issues.apache.org/bugzilla/show_bug.cgi?id=10565|https://issues.apache.org/bugzilla/show_bug.cgi?id=10565] claims that "shutdown hooks are not supported in a container environment" although there is no such restriction in the servlet spec, which would make this a tomcat issue (it does sound like that tomcat6.exe wrapper is somehow involved). Unfortunately, tomcat does NOT issue the AFTER_STOP_EVENT if killed before it has completed its start-up (it appears its own shutdown hook, which sends the event, is not registered until it has fully come up); thus the need for a shutdown hook (at least, up until it's fully up). A shutdown hook is still required in my case for clean-up after tomcat is completely out of the picture. It sounds like the proper architecture here is to really embed tomcat in an application, and create a shutdown hook at the outer level.
Educate me some more. The above description certainly seems like you are suggesting that both of the following are true.
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Perhaps what is actually happening it that addShutdownHook() is never being called at all? Thus of course any processing of the thread associated with that would never, ever run.
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Private info removed as required by the Verizon Wireless Terms of Service
Message was edited by: Admin Moderator

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How many threads are running?

here's the code... i am trying to understand, at each point, how many threads are running:
I understand that one thread belongs to the caller of the start()
& at the same time there is another thread belonging to the instances of each thread (thread1, thread2, thread 3 etc.)
1public class ThreadTester {
2   public static void main( String args[] )
3   {
4      PrintThread thread1, thread2, thread3, thread4;
5
6      thread1 = new PrintThread( "thread1" );
7      thread2 = new PrintThread( "thread2" );
8      thread3 = new PrintThread( "thread3" );
9      thread4 = new PrintThread( "thread4" );
10
11      System.err.println( "\nStarting threads" );
12
13      thread1.start();
14      thread2.start();
15      thread3.start();
16      thread4.start();
17
18      System.err.println( "Threads started\n" );
19   }
}can you tell me if i am counting the number of threads in existance correctly...
LINE#.....CALLER...START...TOTAL THREADS
13..............1.........1.......2
14..............1+1......1+1.....4
15..............2+1......2+1.....6
16..............3+1......3+1.....8
so by the time line 16 executes i have a total of 8 threads,
4 threads belonging to each caller plus
4 threads created by start()
or is it
LINE#.....CALLER...START...TOTAL THREADS
13..............1........1........2
14..............1........1+1.....3
15..............1........2+1.....4
16..............1........3+1.....5
after line 16 executes does the caller thread die, thus leaving only a total of 4 threads?
there is only one thread belonging to the caller at line 13(plus the thread it creates).
at the start of line 14, the previous callers thread is dead & now a new thread is created that belongs to the caller on line 14... etc.

well, i realize at the end there would be 4 threads but im trying to get my head around this explanation in the book:
"A program launches a threads executioin by calling the threads start method, which in turn call the run method. After start launches the thread, start returns to tis caller immediately. The caller then executes concurrently with the lauched thread." there fore if i have 2 concurrent processes, are there 2 threads running????
now having said the above, my question was:
for each line,
how many threads are in existance at
line13
line14
line15
line16
thanks.

ToString() method in my User defined Exception...How is it getting called ?

CustomException.java
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Exception in thread "main" this is my exception at ExceptionTest.main(ExceptionTest.java:8)
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What i see is message "this is my exception" is within the toString() method - which i never called.
From where is the toString() method getting called ?
Also ,
If I want an object of my class to be thrown as an exception object, what should I do?

Your main method is defined as throwing Exception, so the JVM catches the Exception (since nothing in your code does). And it does the equivalent of e.printStackTrace() which, among other things, outputs the result of toString().

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A have specified directory for oracle.tip.adapter.b2b.transportTrace property in ip.properties, however no log file gets generated (restarted b2b).
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Thanks again,
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Stopping a thread from running

Hai
     I am new to java. It would be helpful for me if someone helps me out in doing this.
     Actually in my program ,I should
i. Find out whether a particular file exists in the given directory or not.
ii. If the file doesn't exist, my program should wait for certain timeframe and check for the same file again.
iii. If the program cannot find the required file within the timeout specified, my application should exit.
     I have done (i) and (ii) using threads. But in the case of (iii), I came to know that stop() method is depricated.
     I am providing my code for a better understanding. Could you please let me know, what would be the best way to stop the thread from running after the timeout is reached in my program?
Thanx in advance
import java.io.File;
public class Fileexists implements Runnable
static Thread t;
public static void main(String[] args)
     System.out.println("creation of object");
     FileExists test = new FileExists();
     t = new Thread(test);
     t.start();
// run method
public void run()
     File f = new File("searchfile.txt");
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System.out.println();
if(b == false)
System.out.println("Required file doesnot exists");
try
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catch (InterruptedException e)
     // TODO Auto-generated catch block
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          t.run();
else
System.out.println("Required file found");
} // end of run()
} // end of FileExists class

Actually your use of threads is a difference which makes no difference. The JVM starts an initial thread and runs your main(), at the end of which you start a thread and return. So you've just replaced one thread with another. There's no parallel processing.
The t.run() at the end of your run() method won't work. A particular Thread object can only run once. It will give you an IllegalStateException.
I can't see how multi-threading will help you with this task at all, all you need is a simple loop with a Thread.sleep in it.
If you really want to use a separate thread or Timer to implement a timeout (as an exercise) then use Thread.interrupt() to wind up a thread. The looping thread should test with Thread.interrupted() in it's loop condition, if it's in sleep() when interrupted an InterruptedException will be thrown which you should catch and allow to break the loop and let the thread terminate.
So your loop structure looks like:
try {
while(!Thread.interrupted()) {
    ... do your test
    Thread.sleep(.....);
System.out.println("Thread terminated by detecting interrupted");
} catch(InterruptedException ex) {
     System.out.println("Thread interrupted from sleep");
You can get the Thread for the main thread simply by storing Thread.currentThread() in a Thread reference.
I'd suggest using a java.util.Timer to launch your time-out and leave the loop on the main thread started by the JVM.

Trouble rationalizing use of multi-threading in run of the mill servlets

Hey everybody,
While spending time writing an internal wiki article on servlets for work, I asked myself a very basic question: What does multi-threading buy average servlets where the business logic requires procedural handling of the request?
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What are some of the ways that you are using multi-threading with web applications?
How would you explain why and where you would want to use multi-threading to someone?
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how can we pass arguments to the run ()method?Create classes which implement Runnable that take your runtime parameters as constructor arguments and store them.
eg: if your single thread method is static void foo (int quantity, String name) {
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// caller code
foo(7, "wombats");Then you can make a runnable implementation thus:public class Foo implements Runnable {
final int quantity_;
final String name_;
public Foo (int quantity, String name) {
    quantity_ = quantity;
    name_ = name;
public void run () {
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// caller code
new Thread(new Foo(7, "wombats")).start();
You could overload this method to take parameters in
your class that implements the Runnable interface,
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Java Thread.. System Clock gets slower..

Hello All!
I have never came accross such problem in my last 4 years of java development but right now its sucking my brain like any thing..
Let me clerify what my application is doing.
A node which is basically thread is executed and as it performs its job it is stopped by breaking the while loop like logic and then a method isRunnable() is called to calculate the time to run the thread again on the basis of pre-defined schedule (e.g. after 1 minute). so what i was doing in this method i was calling wait (sheduledMinutes*60*1000).
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Well yeah u r right. I figured it out that it was just my threads running slowly. But the threads ran immediately there was another reason for that. My threads were waiting for the sheduled minutes to run again. In the mean while if i presed the stop button to stop the thread i was just setting the stop variable value to true. Which was basically the check in the while loop in run method. U can notice the thread still sleeping due to the call to wait method. And then if again mean while i press start button i called System.gc(). and then pass the current thread to new Thread like Threa t = new Thread(node); t.start();
Now u can c another thread has been created but the last one was not collected by the garbage collector as it was still waiting and doing something ofcourse not dead. So now when new thread stops these was a possiblity of last thread ( one in waiting state) to run according to schedule and it make the current thread run immediately.
I hope u can understand how difficult it was for me to figure this thing out :)
But after 3/4 hours hair tearing i got the bug and then when i was stopping a thread i infact broke the waiting loop as well. Now the thread was dead and collected by garbage collector before new thread could start :)
Hhhhhhhhhhhhhh sometimes programmign really sucks.
Have fun. and thanx for ur concern..
Regards

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Erm, i tried to highlight the code and then press the code tag but after posting it is still plain, and there is no way to edit the post, sorry about that, next time i'll try. About the book "Filthy Rich Clients", no i don't have it, is there any free version of similiar resources?
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Program freezes when a thread is run in another class.

I have a class that extends Thread, and then I have a GUI that needs this thread.
The thread class looks like this:
public class ScoreboardCheck extends Thread
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In the GUI class, how am I suppose to continously update the clock without this thing freezing up? I've tried implementing runnable in the GUI class, but that didn't work.

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