Hi,
I have another question.
What is the advantage of arraylist over vector.
Why arraylist is widely used instead of vector in java programming?
Thanks in advance.....

don't use Vector unless you have to and remember that you don't have to unless you've no other option (like it's a required argument to some method). That's all you need to know.

may be it is a legacy class. but I was asked both the questions in Interview.
That is why I need to know the answers.

Well in relation to threads, I major difference is that a Vector is synchronized and an ArrayList is not synchronized. What this means is, if two threads attempt to access a
Vector it will be synchronized. One thread will have to wait until the
other thread is finished accessing the Vector. With an ArrayList you have
to create wrappers to synchronize access to the ArrayList or you will have
undefined behaviour.

Also:

http://forum.java.sun.com/thread.jsp...sageID=4136184

If you were asked that in a job interview and didn't know the answer they're right to fail you.
If you applied for a job where you should know the answer and you not only don't know it but don't know where to find it (and it's easy to find, everyone should know who's programmed in Java for more than a day or so) you don't deserve any job at all.