Thread's run method

I cannot unserstand why the output of this program is:
axa axa
class A extends Thread
public void run()
System.out.print("axa ");
public class Main
public static void main(String[] args) throws Exception
Thread t = new Thread(new A());
t.run();
t.start();

Guestios wrote:
Why the
t.run();
calls the run() method of the Class A?
t is just an instance of class ThreadThe implementation of the run() method in the Thread class looks like this:
public void run() {
if (target != null) {
target.run();
}The 'target' variable is the Runnable you passed to the Thread in the constructor, which was an instance of A, so it's run() method was called.
Jim S.

Similar Messages

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.

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");
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interface BackgroundTaskInf{
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}

Thread Callable call() method question

i am using callable interface and i need to return from call() method before process gets over.
basically i have infinite loop in call() method which gets data from streaming services,
and once i format the data and send back to EDT to update UI constantly.
i am using call() method because my call() (same as run() runnable) throws exception if there is any problem in receiving data.
i don't care for return value from call(). i only care if there is any exception.
if i don't do task.get().... then everything works fine, but then i dont get any executionException as well, (which i really care for)
FutureTask<String> task = new FutureTask<String>(resParser);
Thread thread= new Thread(task);
thread.start();
try{
String result = task.get();
}catch(ExecutionException e){
e.printStackTrace();
}catch(InterruptedException ex){
}any solution ??
Thanks

You will need to re-consider your requirements. You either call get() and block the active thread, or you let the thread continue to run and don't call get().
Your solution would be to catch the exception someplace else and feed the exception (or message) to wherever you need it. Why do you think you need to catch the exception right here (which is apparently in your EDT)? Why not catch it in the Thread's run method and deal with it there?

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
     public String x="Inside";
     public void run()
          x+="the run method";

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() {
         x+="the run method";
         synchronized(this) {
          notify();
    public static void main(String[] args) throws InterruptedException {
     SampleThread t = new sampsynch().new SampleThread();
     t.start();
     synchronized(t) {
         t.wait();
     System.out.println(t.x);
}

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 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.

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...

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.

Is it possible to throw an exception from run method of a thread?

Is it possible to throw an exception from "run method of a thread"(implemented as runnable implementation)?
Is it advisable to do so?

Is it possible to throw an exception from "run method
of a thread"(implemented as runnable
implementation)?Yes, an unchecked one. Runtime exceptions.
Is it advisable to do so?If you mess up it happens automatically. But basically: no.

Thread.run() method..

I was wondering how the "Thread.run()" method get called. I started with "Thread.start()" and found it calls the "Thread.start0()" which is a native method.
I downloaded the JDK 5 source code and went to "j2se\src\share\native\java\lang\Thread.c". In "Thread.c" I found a mapping of "start0()" with "JVM_StartThread".
After that I opened the "hotspot\src\share\vm\prims\jvm.cpp". From line no 2257 to 2316 I saw the implementation of "JVM_StartThread".
In side "JVM_StartThread", I saw there is a call to "Thread::start(native_thread)" and opened the "hotspot\src\share\vm\runtime\Thread.cpp". In "Thread.start()" method there is a call to "os::start_thread(thread);".
In "hotspot\src\share\vm\runtime\os.cpp" the "os::start_thread()" calls the "pd_start_thread(thread);" method. But I did not get the "pd_start_thread(thread);" method in os.cpp.
Note: I am java programmer and hardly understand the C/C++ languages. But had a doubt how the run() method get called and how the Thread.start() method works. But I got stuck here.
Kindly help me to know how the flow goes, when we call the Thread.start() and how the run() method is linked to it.

But I did not see anything in the os.cpp. In fact i did not find the "pd_start_thread(thread);" .
void os::start_thread(Thread* thread) {
// guard suspend/resume
MutexLockerEx ml(thread->SR_lock(), Mutex::_no_safepoint_check_flag);
assert(thread->is_baby_thread(), "thread has started");
thread->clear_is_baby_thread();
OSThread* osthread = thread->osthread();
// A thread may be suspended in the presence of the profiler.
// Only start thread when it's not suspended.
osthread->set_state(RUNNABLE);
if (!thread->is_vm_suspended()) {
pd_start_thread(thread);
}

Run() method in Thread.

Hi,
why we not declare run() method synchronized ? if we do so , then what happen ?
Thanks in advance ...

user13484853 wrote:
EJP wrote:
What is synchronization, synchronization method, synchronization blockThis page is complete drivel. There were errors and/or nonsense everywhere I looked.
Core Java Thread ConceptThis page is complete drivel as well. It's not even written in standard English. It reads like somebody has copied down a Powerpoint presentation without bothering to add any meaning.
Thanks & Regards,No thanks. Cited reference sites need to be a lot better than this thanks. You should cite the Sun Java Tutorial rather than any if this garbage.Everybody should not be perfect. Everybody not have good English skills.If you're going to publish something educational, you owe it to your readers to have proper grammar and clear communication in whatever language you're publishing in. Otherwise, the material is useless.
In that site synchronization concept any one can simply understand.No, it was hard to understand.
I accept that not completely explained. But the over all concept is there.That's not good enough.
You present limited information, it's poorly explained, and it has multiple errors. There's no value in that, especially since anybody can go to any of several other sites and get correct, clearly explained information.

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

How run method is called in a thread

Hello,
If I call start method of a thread, then I want to know if run method is automatically called or not.
Thank you

A tutorial on threads would doubtlessly contain much of the information you're after. There might be something in the Java Tutorial that's worth looking at.
Have you tried it to find out what the behaviour is? It's really not very surprising...
In summary, though:
The run method of a Thread is called when the Thread is started. You can confirm this by overriding the run method if you want:
Thread myThread = new Thread() {
public void run() {
System.out.println("WOO HOO - Run!!");
System.out.println("Starting thread");
myThread.start();
System.out.println("Thread started");Hope this helps.

Thread's run method

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