This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
The exception message will tell you on exactly which line it occurs. That will help you work it out, but if it's not enough you should tell us which line, as it makes it much easier for us to help you.
However, I think I see the problem. Look at line 13. Was dob supposed to be a parameter passed in to the constructor? Because at the moment you're trying to initialise the instance variable dob with itself. So the reference you're trying to call getTime() on is null.