Volatile in java

Question

Hi,
I am trying to run the following program to see how volatile variable is shared by 2 threads! The result of the program does not satisfy the definition of volatile. Please help me in checking if it is the right way ... or the codes needs any change.
package com.msg.jresearch.threads;
class ExampleThread extends Thread {
     private volatile int testValue;
     public ExampleThread(String str) {
          super(str);
     public void run() {
          for (int i = 0; i < 3; i++) {
               try {
                    System.out.println(getName() + " : " + i);
                    if (getName().equals("Thread 1 ")) {
                         testValue = 10;
                    if (getName().equals("Thread 2 ")) {
                         System.out.println("Test Value : " + testValue);
                         Thread.sleep(20000);
               } catch (InterruptedException exception) {
                    exception.printStackTrace();
public class VolatileExample {
     public static void main(String args[]) {
          new ExampleThread("Thread 1 ").start();
          new ExampleThread("Thread 2 ").start();
Thanks
-MS

Answer 1

MS-Ghotra wrote:
Hi ,
Thanks for clarifying it! Appreciate your help.
I tried following, but unfortunately keeping volatile or no, gives the same result..may be becuase i am updating the instance variable directly.Volatile has nothing to do with it. The real problem in your original code is that you had 2 different objects. Taking away volatile will not fix that, and nobody said or implied that it would.
If you fix the 2 different objects problem and have both threads working on 1 object, then volatile will matter, and you will definitely want volatile.
As you said "no multithreading"We said that?
Trying to create an example of 2 threads working on a common instance. If you can direct me to an example where i can debug & practice it. It will be great.Google for java multithreading tutorial. You'll find lots of examples.
package com.msg.jresearch.threads;If you want to post code, use code tags so it's readable. Copy paste directly from your original source in your editor (NOT from your earlier post here, which has already lost all formatting), highlight the code, and click the CODE button. Also don't include a bunch of commented out lines. That's just clutter that makes it hard to read. I didn't even try reading your code because of these two issues.