Stopping a Thread (no control on run method)

Hi,
How can we stop a Thread like in the following scenario. If we are in the aMethod() and the stopped variable is set to true by some other thread now how can we return from this run method and stop executing the aMethod(). Any tips are helpful.
public void run()
if (stopped)
return;
someOtherClass.aMethod();
Thanks

I miss the scenario here, where a thread is blocked inside a call to some operating system resource (such as accept() or read() or write()).
In this case an InterruptedException travels like pacman up the stack, until it's caught, and I think that it should be a scenario in all cases, because it can apply to the blocking call (where it applies already), the predictable loop (try { while() { } } catch (InterruptedException ie) { }), and the one-off algorithm, even though in the latter case, if it's extremely important that we know exactly what we were doing when we were interrupted, it's difficult to avoid either a) many try-catch-blocks, or b) a very good way of examining the stack at the moment of interruption.
This is, in fact, so important, that I would like to urge Sun to change the API for java.lang.Runnable into
public interface Runnable {
public abstract void run() throws InterruptedException;
}Because, in this way, any thread will always have an endpoint. If you choose to rethrow the exception you still mess up the JVM, of course, like it was, causing it to exit. But at least you must provide yourself with the opportunity to let threads not end, or always die softly.

Similar Messages

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");
     boolean b = f.exists();
System.out.println();
if(b == false)
System.out.println("Required file doesnot exists");
try
     t.sleep(20000);
catch (InterruptedException e)
     // TODO Auto-generated catch block
     e.printStackTrace();
          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.

Run method in Thread subclass

run method of Base calss is executing when I run this code. If I remove Base.run() it Test1.run() is getting executed. can anybody explain why.?
class Base extends Thread{
public native String getTime();
     Base(Runnable r)
          super(r);
     public void run()
          System.err.println("In Base");
public class Test1 implements Runnable {
boolean bStop;
public static void main(String argv[]){
     Test1 m = new Test1();
     m.go();
public void go(){
     Base ts = new Base(this);
     ts.start();
public void run(){
          System.out.println(" in Test1");
}

What you have done is very odd, and wrong. Why do you have a subclass to thread that overrides the run method?
This is what the default implementation for the run method in the Thread class looks like:
    public void run() {
        if (target != null) {
            target.run();
    }Where target is the runnable that you passed into the constructor. Your implementation of run does not invoke that runnable.
Kaj

Stop current thread

I have got a Thread (made from swing thread).
In the run() method i create a frame with a button that has an "actionperformed" and I show this frame and I put a loop like "
while(true){
Thread.currentTread.sleep(1000);
System.out.println("bip");
But in the button action I try to kill this Thread.
But, no one of the methods from Thread class "yield", "destroy", "interrupt" seems to work.
QUESTION :
==> How can I do to kill a Thread when I have his name or when it is the current Thread.

Right - your best option is to either make the thread null (thus removing the object and stopping the thread from running), which is a bit heavy handed. Be careful of this, especially if you'll be creating new instances all the time - creating and scheduling threads can be quite processor and time intensive.
The other option is to have the while loop use a boolean variable, such that you can do something like
// instnace variable:
private boolean running = true;
// now a method to modify it:
public void setRunning(boolean run)
running = run;
//some more code in your class...
// now the body of the run method:
while(running)
Thread.currentTread.sleep(1000);
System.out.println("bip");
}Thus, when someone calls yourObjectName.setRunning(false), the run() method will quit.
All you have to do now is call yourObjectName.start() to make it run again.
I can't think of any cleaner ways to do this, so if they're any Java Gurus out there, help me out here.
So, do this if you want to stop a thread running; but if you really want to kill it, and not use it again, make the object null.
Let me know if this works for you,
Rich

Java threads. Are they running at the same time?

Hello everybody. I am implementing a multiagent system in java and at some point in the program i need a specific function (from a specific class) to run at the same time in several "copies". Those functions are communicating with each other with some messages, so as you can understand not running at the same time is a big problem because of this messages.
Below i am giving you an example of the code i am using. I would like your opinion whether those functions are running parallel or serial. If they are not running parallel what should i do? Any opinion or something that can help me would be perfect. Thanks in advance.
//my class
public class Agent extends Thread {
                       public void MinConflicts(Agent array[],int max_moves){//code in here}
public static void main(String[] args) throws IOException {
              Agent[] fbi = new Agent[num] //num is inserted by the user
             //code here
             for(i=0;i<num;i++){
                     fbi.start(); //starting the treads
for(i=0;i<num;i++){
fbi[i].MinConflicts(fbi,max_moves); //running the function that i want to run parallel
//code here also :)

What you appear to be doing here is creating an array of Thread references (which I hope at some point gets populated with actual Thread object references!)......because your first loop is wanting to cycle through each array slot starting the referenced Thread. Then the next loop iterates through the array again, this time calling the method for each Thread object.
Assuming that you do populate the array, what this code will do is start each Thread which, I believe, will start and immediately terminate because run() has not been over-ridden. The second loop winds up calling the method for each Thread in the array. You are actually calling it from the main thread though. So, as previously advised, I think that you will run each method sequentially.
The direction that I would head with this is to override run() in your agent Thread and have that run() method call the MiniConflicts() method. Then, in your main routine you can do away with the second for loop. The looping start will start all of the individual threads and they will execute the run() method......which in essence will be executing your MiniConflicts method.
This reply is NOT a total design... I am sure that there are holes to be filled... but I think that will get you headed in the right direction.

Stopping a Thread (where I don't have control of run)

Is there any way to stop a thread whose run method simply calls a method of another class?
For example:
public class myThread extends Thread
private String className = ...;
public void run()
// get className's "main" method and run it

Actually...Smarsh is right. This is the correct way
to stop a thead....stop() is deprecated because it can
cause a deadlock condition. So, in run(), if you
defined a boolean like "bStopThread" run would look
like this:
public void run() {
if(bStopThread)
return;
// if we drop here...this is the rest of our run
un code
Yeah, I get that's how you should stop a thread...
Let me rephrase the question a little. Say the thread's run method looks similar to this:
public void run()
if (stopped)
return;
someOtherClass.aMethod();
}Once it's in aMethod, I have to let it run until it's done, right? There's no other way to stop a thread other than checking a stop condition?

How to stop a thread without the deprecated Thread.stop() method?

Hi,
I am writting a server application that launches threads, but the run() implementation of these threads are not written by me (i.e. i have no control over them): they are third-party programs. That's why i could not use the well known Java tutorial way to stop a thread (i.e. with a global variable that indicates the thread state).
I would like my server to be able to stop these threads at any time, but without using the deprecated Thread.stop() method.
Any ideas ?
Thanks in advance,
Fabien

Thanks Pandava!
I was arrived at the same conclusion... As to me, it is a very bad issue, because it means for example that a servlet server can not stop any servlet it launches (especially for preventing infinite loops).
If i want to be strictly JDK 1.4 compliant, i should not use Thread.stop(). But if i don't use it, i don't have any ideas of how stop a thread that i don't control...

How can I get the variable with the value from Thread Run method?

We want to access a variable from the run method of a Thread externally in a class or in a method. Even though I make the variable as public /public static, I could get the value till the end of the run method only. After that scope of the variable gets lost resulting to null value in the called method/class..
How can I get the variable with the value?
This is sample code:
public class SampleSynchronisation
     public static void main(String df[])
sampleThread sathr= new sampleThread();
sathr.start();
System.out.println("This is the value from the run method "+sathr.x);
// I should get Inside the run method::: But I get only Inside
class sampleThread extends Thread
     public String x="Inside";
     public void run()
          x+="the run method";
NB: if i write the variable in to a file I am able to read it from external method. This I dont want to do

We want to access a variable from the run method of a
Thread externally in a class or in a method. I presume you mean a member variable of the thread class and not a local variable inside the run() method.
Even
though I make the variable as public /public static, I
could get the value till the end of the run method
only. After that scope of the variable gets lost
resulting to null value in the called method/class..
I find it easier to implement the Runnable interface rather than extending a thread. This allows your class to extend another class (ie if you extend thread you can't extend something else, but if you implement Runnable you have the ability to inherit from something). Here's how I would write it:
public class SampleSynchronisation
public static void main(String[] args)
    SampleSynchronisation app = new SampleSynchronisation();
public SampleSynchronisation()
    MyRunnable runner = new MyRunnable();
    new Thread(runner).start();
    // yield this thread so other thread gets a chance to start
    Thread.yield();
    System.out.println("runner's X = " + runner.getX());
class MyRunnable implements Runnable
    String X = null;
    // this method called from the controlling thread
    public synchronized String getX()
      return X;
    public void run()
      System.out.println("Inside MyRunnable");
      X = "MyRunnable's data";
} // end class MyRunnable
} // end class SampleSynchronisation>
public class SampleSynchronisation
public static void main(String df[])
sampleThread sathr= new sampleThread();
sathr.start();
System.out.println("This is the value from the run
method "+sathr.x);
// I should get Inside the run method::: But I get
only Inside
class sampleThread extends Thread
public String x="Inside";
public void run()
x+="the run method";
NB: if i write the variable in to a file I am able to
read it from external method. This I dont want to do

How can I get the variable with the value from Thread's run method

We want to access a variable from the run method of a Thread externally in a class or in a method. Even though I make the variable as public /public static, I could get the value till the end of the run method only. After that scope of the variable gets lost resulting to null value in the called method/class..
How can I get the variable with the value?
This is sample code:
public class SampleSynchronisation
     public static void main(String df[])
sampleThread sathr= new sampleThread();
sathr.start();
System.out.println("This is the value from the run method "+sathr.x);
/* I should get:
Inside the run method
But I get only:
Inside*/
class sampleThread extends Thread
     public String x="Inside";
     public void run()
          x+="the run method";
NB: if i write the variable in to a file I am able to read it from external method. This I dont want to do

Your main thread continues to run after the sathr thread is completed, consequently the output is done before the sathr thread has modified the string. You need to make the main thread pause, this will allow sathr time to run to the point where it will modify the string and then you can print it out. Another way would be to lock the object using a synchronized block to stop the main thread accessing the string until the sathr has finished with it.

How to throw Exception in Thread.run() method

I want to throw exception in Thread.run() method. How can I do that ?
If I try to compile the Code given below, it does not allow me to compile :
public class ThreadTest {
     public static void main(String[] args) {
     ThreadTest.DyingThread t = new DyingThread();
     t.start();
     static class DyingThread extends Thread {
     public void run() {
     try {
               //some code that may throw some exception here
          } catch (Exception e) {
          throw e;//Want to throw(pass) exception to caller
}

(a) in JDK 1.4+, wrap your exception in RuntimeException:
catch (Exception e)
throw new RuntimeException(e);
[this exception will be caught by ThreadGroup.uncaughtException() of this thread's parent thread group]
In earlier JDKs, use your own wrapping unchecked exception class.
(b) if you know what you are doing, you can make any Java method throw any exception using Thread.stop(Throwable) regardless of what it declares in its "throws" declaration.

When we create JDialog inside Thread's run() method it is creating problem

I have application that has feature that mainframe will be locked after three minutes and the time when it is locked it will show other locked dialog.
Now my problem is given below:
I have created one Dialog inside Threads run() method and this thread will execute when mainframe is locked.So what is happening is when mainframe is locked internally Thread is doing its job (its job is to display one dialog) and it is displaying dialog but mainframe is locked and still it is showing that dialog.This should not happen in our application when mainframe is locked nothing should come outside.
simple code sample is given below:
SwingUtilities.invokeLater(new Runnable()
JDailog dlg = new JDialog();
dlg.pack();
dlg.show();
Now when my applications mainframe is locked and thread is doing its job when mainframe is locked and it will show one dialog when its run() method will execute and it showing dialog even though mainframe is locked.This is major issue for me.please help me.
sample code may contain compile errror but this only to give understanding what i am doing actually i cant show my original code.
But show me some work around for this problem.Why dialog is coming outside when mainframe is locked?
Please help me.I cant use delay inside run() method because of performance.
Is there any way to control this behaviour?

public class BackGroundThread extends javax.swing.JFrame implements BackgroundTaskInf {
    boolean isMainWindowActive = false;
    /** Creates new form BackGroundThread */
    public BackGroundThread() {
        initComponents();
        new DBBackgroudProcess(this).start();
    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
    // <editor-fold defaultstate="collapsed" desc=" Generated Code ">
    private void initComponents() {
        jDialog1 = new javax.swing.JDialog();
        jLabel1 = new javax.swing.JLabel();
        jLabel2 = new javax.swing.JLabel();
        jButton1 = new javax.swing.JButton();
        jLabel1.setText("JOB DONE");
        javax.swing.GroupLayout jDialog1Layout = new javax.swing.GroupLayout(jDialog1.getContentPane());
        jDialog1.getContentPane().setLayout(jDialog1Layout);
        jDialog1Layout.setHorizontalGroup(
            jDialog1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jDialog1Layout.createSequentialGroup()
                .addGap(95, 95, 95)
                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 65, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(240, Short.MAX_VALUE))
        jDialog1Layout.setVerticalGroup(
            jDialog1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jDialog1Layout.createSequentialGroup()
                .addGap(22, 22, 22)
                .addComponent(jLabel1)
                .addContainerGap(22, Short.MAX_VALUE))
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        jLabel2.setText("Background work in progess");
        jButton1.setText("unlock");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(56, 56, 56)
                .addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 218, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(126, Short.MAX_VALUE))
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(263, Short.MAX_VALUE)
                .addComponent(jButton1)
                .addGap(74, 74, 74))
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(40, 40, 40)
                .addComponent(jLabel2)
                .addGap(37, 37, 37)
                .addComponent(jButton1)
                .addContainerGap(43, Short.MAX_VALUE))
        pack();
    }// </editor-fold>
    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
        isMainWindowActive = true;
        backgroundTaskFinished();
     * @param args the command line arguments
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new BackGroundThread().setVisible(true);
    public void backgroundTaskFinished(){
        if(isMainWindowActive) {
            jDialog1.setSize(200,200);
            jDialog1.setVisible(true);
            jLabel2.setText("Task is finished");
    // Variables declaration - do not modify
    private javax.swing.JButton jButton1;
    private javax.swing.JDialog jDialog1;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    // End of variables declaration
class DBBackgroudProcess extends Thread {
    BackgroundTaskInf infObj;
    public DBBackgroudProcess(BackgroundTaskInf infObj){
        this.infObj = infObj;
    public void run(){
        try{
            // here you can do your backgroudn task
            System.out.println("In BackGroud task");
            Thread.sleep(1000);
            System.out.println("task completed");
            infObj.backgroundTaskFinished();
        }catch(Exception e){
            e.printStackTrace();
interface BackgroundTaskInf{
    public void backgroundTaskFinished();
}

How can I kill all Threads of the same class from within the run() method?

Ok
I have a class called Consumer that extends Thread
I have several Consumer threans running... but, when a certain condition is true (within the run() method) in ANY of the threads, I want to kill ALL the threads of that object.
is this possible?

I know this is gonna be too demanding, but can someone please tell me why my Consumer's run() method never reaches the System.out.println( "ALL CONSUMING DONE") line
Create a multi-threaded prime number calculator that is based on the producer-consumer model
using semaphores. Your program should be able to check for prime numbers in a range specified
by the user and with a variable number of threads. Example:
$ java PrimeFind 3 5000 10000
should use 1 producer and 2 consumers (3 threads in total, obviously the minimum is 2) to find all
the prime numbers in the range [5000,10000].
The producer should: use a buffer to store candidate numbers that have to be checked for
primality.
Consumers should: read from the buffer, check if a number is prime and update the status of the
program accordingly (e.g. show the number on the screen, or save it to a file)
import java.util.concurrent.Semaphore;
import java.io.*;
public class Assign1 {
static int fromThisNumber;
static int toThisNumber;
static int numberOfThreads;
static int buffer[];
static Semaphore ready;          /*This semaphore is used by the Producer to signal
                                     an "OK" to the consumers*/
static Semaphore critical; /*This is a Mutex semaphore. It allows only 1 consumer
                                     to enter his critical section.
static Semaphore counter;     /*This semaphore acts as a counter.
                                    Instead of having a global variable
                                     incremented each time, we just release()
                                     this semephore when we find a prime number
                                     Because remember that release() increments permits
static Producer prod;
static Consumer cons[];
static int in=0;
static int out=0;
static PrintWriter outFile;
     public static void main (String args[]){
          try{
               outFile=new PrintWriter(new FileWriter("primes.txt"));
               }catch(Exception e){}
          numberOfThreads=Integer.parseInt(args[0]);
          fromThisNumber=Integer.parseInt(args[1]);
          toThisNumber=Integer.parseInt(args[2]);
          buffer=new int[Integer.parseInt(args[2])-Integer.parseInt(args[1])+1];
          ready=new Semaphore(0,false); /*We initialise it to 0 because we wait
                                                  for the Producer to produce atleast a
                                                  item. Suppose ready was 1 and if
                                                  Consumer ran first he would be in an
                                                  empty buffer */
          critical=new Semaphore (1,false);/*We initialise it to 1 because when
                                                     the first Consumer thread tries
                                                     to enter its critical section, it
                                                     should be allowed to;
                                                     Subsequent threads will have to
                                                     wait since only 1 thread can
                                                     access its critical section at a time*/
          counter=new Semaphore(0,false); // duh!
          cons=new Consumer[numberOfThreads-1]; /*numberOfThreads-1 because 1 thread
                                                            is taken by the Producer*/
          //Creating Producer object
          prod=new Producer();
          //Creating the Consumer object and start the thread.
          for(int i=0;i<cons.length;i++)
                    cons=new Consumer();
                    cons[i].start();
          prod.start();
          //Printing to screen and file
/*          for(int i=0;i<buffer.length;i++)
               if(buffer[i]!=0)
                         System.out.println(buffer[i]);
                         outFile.println(buffer[i]);
          System.out.println("Total primes found between "+args[1]+" and "+toThisNumber+": "+counter.availablePermits()+"\n primes.txt written");
          outFile.println("Total primes found between "+args[1]+" and "+toThisNumber+": "+counter.availablePermits());
          outFile.close();*/
static class Producer extends Thread {
     public void run(){try{
          while(in<buffer.length)     /*'in' should always be more than 'out'.Oherwise the consumer will try to access an empty index*/
               {     System.out.println("producing");
                    buffer[in]=fromThisNumber;
                    in++;
                    fromThisNumber++;
                    ready.release();
          catch (Exception e){e.printStackTrace();}
          System.out.println("ALL PRODUCING DONE");
static class Consumer extends Thread {
     int tempout=0;
     public void run(){try{
          System.out.println("before while"+this.getId());
          while(tempout<=in)
               System.out.println("before ready"+this.getId()+" "+ready.availablePermits()+" "+in);
               ready.acquire();
               System.out.println("before critical.acquire"+this.getId());
               critical.acquire();
               tempout=out;
               out++;
               critical.release();
               if(!isPrime(buffer[tempout]))
                    {System.out.println(buffer[tempout]+" by "+this.getId());buffer[tempout]=0;}
               else {counter.release();System.out.println("prime added: "+buffer[tempout]+" by "+this.getId());}
               critical.acquire();
               tempout=out;
               System.out.println("tempout:"+tempout+" of "+this.getId());
               critical.release();
          System.out.println("ALL CONSUMING DONE"+this.getId());
     catch(Exception e){e.printStackTrace();}
     //Prime number-checking method
     public boolean isPrime(int n){
          for(int i=2;i<=(n/2);i++)
               if(n%i==0)
                    return false;
          return true;
======================
import java.util.concurrent.Semaphore;
import java.io.*;
/* 3 questions to ask Barlas
* Why error if I start the Consumer threads before Producer
* Why does the counter semaphore always give a +1 result at the end
* Is there a way I can verify that all the work is not being done by only 1 consumer thread? In other words, the workload is being shared properly
* if I put ready.acquire() outside or inside the while loop, its not making any difference, why?
* Strangely, its not making any difference if I playing with the release() and aquire() of the semaphores, WHY?!?!
public class Assign1 {
static int fromThisNumber;
static int toThisNumber;
static int numberOfThreads;
static int buffer[];
static Semaphore ready;          /*This semaphore is used by the Producer to signal
                                   an "OK" to the consumers*/
static Semaphore critical; /*This is a Mutex semaphore. It allows only 1 consumer
                                   to enter his critical section.
static Semaphore counter;     /*This semaphore acts as a counter.
                              Instead of having a global variable
                                   incremented each time, we just release()
                                   this semephore when we find a prime number
                                   Because remember that release() increments permits
static Producer prod;
static Consumer cons[];
static int in=0;
static int out=0;
static PrintWriter outFile;
     public static void main (String args[]){
          try{
               outFile=new PrintWriter(new FileWriter("primes.txt"));
               }catch(Exception e){}
          numberOfThreads=Integer.parseInt(args[0]);
          fromThisNumber=Integer.parseInt(args[1]);
          toThisNumber=Integer.parseInt(args[2]);
          buffer=new int[Integer.parseInt(args[2])-Integer.parseInt(args[1])+1];
          ready=new Semaphore(0,false); /*We initialise it to 0 because we wait
                                                  for the Producer to produce atleast a
                                                  item. Suppose ready was 1 and if
                                                  Consumer ran first he would be in an
                                                  empty buffer */
          critical=new Semaphore (1,false);/*We initialise it to 1 because when
                                                  the first Consumer thread tries
                                                  to enter its critical section, it
                                                  should be allowed to;
                                                  Subsequent threads will have to
                                                  wait since only 1 thread can
                                                  access its critical section at a time*/
          counter=new Semaphore(0,false); // duh!
          cons=new Consumer[numberOfThreads-1]; /*numberOfThreads-1 because 1 thread
                                                            is taken by the Producer*/
          //Creating Producer object
          prod=new Producer();
          //Creating the Consumer object and start the thread.
          for(int i=0;i<cons.length;i++)
                    cons[i]=new Consumer();
                    cons[i].start();
          prod.start();
          //Printing to screen and file
/*          for(int i=0;i<buffer.length;i++)
               if(buffer[i]!=0)
                         System.out.println(buffer[i]);
                         outFile.println(buffer[i]);
          System.out.println("Total primes found between "+args[1]+" and "+toThisNumber+": "+counter.availablePermits()+"\n primes.txt written");
          outFile.println("Total primes found between "+args[1]+" and "+toThisNumber+": "+counter.availablePermits());
          outFile.close();*/
static class Producer extends Thread {
     public void run(){try{
          while(in<buffer.length)     /*'in' should always be more than 'out'.Oherwise the consumer will try to access an empty index*/
               {     System.out.println("producing");
                    buffer[in]=fromThisNumber;
                    in++;
                    fromThisNumber++;
                    ready.release();
          catch (Exception e){e.printStackTrace();}
          System.out.println("ALL PRODUCING DONE");
static class Consumer extends Thread {
     int tempout=0;
     public void run(){try{
          System.out.println("before while"+this.getId());
          while(tempout<=in)
               System.out.println("before ready"+this.getId()+" "+ready.availablePermits()+" "+in);
               ready.acquire();
               System.out.println("before critical.acquire"+this.getId());
               critical.acquire();
               tempout=out;
               out++;
               critical.release();
               if(!isPrime(buffer[tempout]))
                    {System.out.println(buffer[tempout]+" by "+this.getId());buffer[tempout]=0;}
               else {counter.release();System.out.println("prime added: "+buffer[tempout]+" by "+this.getId());}
               critical.acquire();
               tempout=out;
               System.out.println("tempout:"+tempout+" of "+this.getId());
               critical.release();
          System.out.println("ALL CONSUMING DONE"+this.getId());
     catch(Exception e){e.printStackTrace();}
     //Prime number-checking method
     public boolean isPrime(int n){
          for(int i=2;i<=(n/2);i++)
               if(n%i==0)
                    return false;
          return true;
===========================
BTW, when I tried to change extends Thread to implements Runnable I got some kinda of error.
Actually, my program is pretty complete... its just that something if messed up in my Consumer's run() method's while loop... I think
I know guys its crazy to ask ya'll to look at so much code, but.... I'd really appreciate it. This assignment is killing me, been at it since 10 hours now....

How to get value from Thread Run Method

I want to access a variable from the run method of a Thread externally in a class or in a method. Even though I make the variable as public /public static, I could get the value till the end of the run method only. After that it seems that scope of the variable gets lost resulting to null value in the called method/class..
How can I get the variable with the value?
This is sample code:
public class SampleSynchronisation
public static void main(String df[])
sampleThread sathr= new sampleThread();
sathr.start();
System.out.println("This is the value from the run method "+sathr.x);
/* I should get Inside the run method::: But I get only Inside */
class sampleThread extends Thread
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I think this is what you're looking for. I hold up main(), waiting for the results to be concatenated to the String.
public class sampsynch
    class SampleThread extends Thread
     String x = "Inside";
     public void run() {
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         synchronized(this) {
          notify();
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     synchronized(t) {
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}

Passing parameters to run() method of a thread?

hello ppl
is it possible to pass any parameters to the run() method of a thread
moreover if i create a thread foo the only method that can run is run() ? i know that i can have more methods and just call them via run().
i mean that if i create the constructor of the foo class then first the constructor will be called and then the run() method.but in this way only the code inside run() will run autonomously(meaning that for example i'll be able to press a button of my gui).
thx in advance. =)

not sure I understand the question completely, but you can try the following. Set up whatever arameters your requiring as member variables of your Runnable. Overload the run() method with parameter list you need. In this overloaded method initialize the member variables in your runnable, which can be used in the run() , no arg version,/ Then the last line of the overloaded version call run(), again no-arg version.
Not really familiar with thread programming, but I dont see why this wont work.
Hopefully I understood the question correctly, and this is of some help...

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I need to stop all the threads that are currently running in my application. How to do this.

call System.exit();

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