This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
Normally not, but classes like String and the primitive wrappers (Integer, Boolean, etc) are immutable. That means that once created they can never change. It is therefore safe to share them among multiple objects, methods and threads without any problems.