Final modifier can be applied to four java constructs . 1. Final variables final parameters anonymous local classes 2. Final fields declare constants aggregation vs. Acquaintance enforce atomicity of object creation declare invariants for performance conclusion on final fields 3. Final methods enforce invariant code for security for performance? 4. Final classes enforce composition over inheritance for security the final modifier can be applied to four java constructs: 1. Variables: a final variable can be set once and only once. 2. Fields: a final field can also be set only once, by the constructor of the class which defines it. 3. Methods: a final method cannot be overridden nor hidden. 4. Classes: a final class cannot be extended.