Tech Mahindra interview question

First round: Your projects, How to dynamically load a class, OOPs concepts, Difference in between Abstract class and Interface, Thread life cycle, Synchronized block and use, Immutable class, Servlet life cycle and how servlet works Second round: First round: Your projects, OOPs concepts, Difference in between Abstract class and Interface, Thread life cycle, String constant pool, What is Immutable class and how to create it, Servlet life cycle and how servlet works, Singleton design pattern, How to handle clone and serialization concepts in Singleton class, Difference in between JSON & XML Techno-managerial round: Your projects, RESTful webservices, Runtime polymorphism