Tough Java Interview Questions

Can you tell us whether or not Java can furnish any construct if we intend to find out the size of an object?
What is your understanding by wrapper classes?
Please illustrate runtime exceptions.
How would you differentiate between an exception and an error?
Tell us your experience about creation of custom exception.
Please narrate the various methods followed to handle exceptions.
Each try block should be followed with a catch block. What is your comment on this statement?
Suppose I write System.exit (0); which is towards the end of a try block, do you think the final block would still execute?
Narrate one instance where your experience in Java helped you to deal with a complex programming project.
What according to you are the essential pre-requisites to pioneer in the field of Java programming?
Cite one instance where your skill and expertise in Java helped your previous employer.