In Java, we use the final keyword to prevent some classes from being extended. Simply prefix a class header with final, as in final class Password.

Une proposition d'évolution du JDK veut lancer des avertissements sur l'usage de Deep Reflection dans Java pour modifier les champs finaux. Elle prépare ainsi à l'interdiction de leur mutation ...

Proposal would issue warnings about uses of deep reflection to mutate final flelds, preparing for a future Java release that disallows mutation of final fields by default.