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.
The HashSet class uses both the equals() and hashCode() method to determine equality. If the equals method reports that two objects are the same, but they have different hashcodes, then the contract is broken. It may or may not work.