Why do we need threadlocal in Java

The ThreadLocal class in Java enables you to create variables that can only be read and written by the same thread. Thus, even if two threads are executing the same code, and the code has a reference to aThreadLocal variable, then the two threads cannot see each other’s ThreadLocal variables.

<pre lang=’java’>

public class ThreadLocalExample {


    public static class MyRunnable implements Runnable {

        private ThreadLocal<Integer> threadLocal =
               new ThreadLocal<Integer>();

        @Override
        public void run() {
            threadLocal.set( (int) (Math.random() * 100D) );
    
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
            }
    
            System.out.println(threadLocal.get());
        }
    }


    public static void main(String[] args) {
        MyRunnable sharedRunnableInstance = new MyRunnable();

        Thread thread1 = new Thread(sharedRunnableInstance);
        Thread thread2 = new Thread(sharedRunnableInstance);

        thread1.start();
        thread2.start();

        thread1.join(); //wait for thread 1 to terminate
        thread2.join(); //wait for thread 2 to terminate
    }

}

</pre>

Uday Ogra

Connect with me at http://facebook.com/tendulkarogra and lets have some healthy discussion :)

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