java interview experience in oracle india ,hyderabad

I got call from Oracle for F2F interview on 30th April 2016. I have attended the interview . Two persons did interview, below questions are I have faced during interview time.
1.Tell me about your self this is regular question.
2.How much rating you can give on core java for your self(1-10)
3.How will create immutable class in java.

4.How can retrieve only duplicate employee names from EMP table
5.How will consume and create WEB service .
6.What is ActionServlet imparts in Struts framework.
7.How to get duplicate elements from Array.
8.Print pyramid numbers like
1 2
1 2 3
1 2 3 4
9.How to get repeated substring in string with out using String API
Exm: abcallabcallabcssssall
10. Explain me about heap sort algorithm.