As I known,these are some rules for making a class immutable: 1. Don't provide any methods that modify the object (known as mutators). 2. Ensure that no methods may be overridden. 3. Make all fields final. 4. Make all fields private. 5. Ensure exclusive access to any mutable components.
[ July 25, 2007: Message edited by: Shoumin Li ] [ July 25, 2007: Message edited by: Shoumin Li ]