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    <p>The problem is that the ++ is not atomic. The code should use <code>AtomicInteger</code> instead. With the <code>static</code> variable, both threads are trying to update the same value and the ++ is actually 3 operations: get, +1, and store. This means that there is a race condition between both of the threads and they are overwriting each other.</p> <blockquote> <p>Why thread 2 is not reading the updated value? If it has to be made static , whats the use of volatile?</p> </blockquote> <p><code>static</code> and <code>volatile</code> do different things. <code>static</code> makes the field associated with the class as opposed to the object instance. <code>volatile</code> forces any read or write of the field to cross a memory barrier. This allows multiple threads to read and update a common field but this does <em>not</em> protected you from multiple operations. If you make the variable <em>not</em> be static then you would not need the <code>volatile</code> since each thread would be working with it's own instance of the field.</p> <p>You should use <code>AtomicInteger</code>. This wraps a <code>volatile int</code> but also provides special handling of increment operations:</p> <pre><code>private static AtomicInteger testValue = new AtomicInteger(1); ... testValue.incrementAndGet(); </code></pre> <blockquote> <p>Can someone give link to a good example of volatile where that variable is not declare static.</p> </blockquote> <p>You would need a <code>volatile</code> on a non-static field when it was shared by multiple threads. For example, if you moved the <code>testValue</code> up into the <code>VolatileExample</code> class and then passed the same instance of the <code>VolatileExample</code> class into both threads so they could access <code>testValue</code>.</p>
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    1. COThanks for you valuable insight, i will test the same, keeping the variable elsewhere.
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    2. COJust to reiterate, you can't do a `++` on a `volatile` regardless if it is static or not @Dhananjay.
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    3. COi tried putting the variable outside the Runnable class.<br/> ' public class Account { public double balance = 0; public static void main(String... s){ Account aAccount =new Account(); DepositThread aDepositThread1=new DepositThread (aAccount); Thread thread1=new Thread(aDepositThread1,"thread1"); DepositThread1 aDepositThread2=new DepositThread1(aAccount); Thread thread2=new Thread(aDepositThread2,"thread2"); thread1.start(); thread2.start(); } } ' But if we are passing the same object in two thread, It will get the updated value anyways?
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