Thread Id Problem

[sonu raj]

class Abc implements Runnable
{
    public void run()
    {
        long l=Thread.currentThread().getId();
        System.out.println(l);
    }
   
    public static void main(String a[])
    {
        Thread t1=new Thread(new Abc());
        Thread t2=new Thread(new Abc());

        t1.start();
        t2.start();

    }
}

When I compile and run the above program I always gets the same output:
i.e.

9
10

I want to know why the output is always 9 and 10, why not 2 and 4 or 4 and 5.etc
Please elaborate!!

[Added code tags - see UseCodeTags]

[Jaikiran Pai]

Closing this thread since this is a duplicate of http://www.coderanch.com/t/589095/threads/java/Thread-Id. Sonu, please do not create multiple threads for the same question.