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.
There are constructors but they are of the default kind. Remember if you don't specify a constructor then the compiler will supply a default (no args) constructor for you. It is this constructor that is used by the EJB Container to create an instance of your Bean's implementation class. You could explicitly define this default constructor if it makes you feel better.