Core Java Questions et reponses d'entretien
Question : What does the "final" keyword mean in front of a variable? A method? A class?Reponse : FINAL for a variable : value is constantFINAL for a method : cannot be overridden FINAL for a class : cannot be derived A final variable cannot be reassigned, but it is not constant. For instance, final StringBuffer x = new StringBuffer() x.append("hello"); is valid. X cannot have a new value in it,but nothing stops operations on the object that it refers, including destructive operations. Also, a final method cannot be overridden or hidden by new access specifications.This means that the compiler can choose to in-line the invocation of such a method.(I don't know if any compiler actually does this, but it's true in theory.) The best example of a final class is String, which defines a class that cannot be derived. |
Enregistrer pour revision
Ajoutez cet element aux favoris, marquez-le comme difficile ou placez-le dans un ensemble de revision.
Connectez-vous pour enregistrer des favoris, des questions difficiles et des ensembles de revision.
Est-ce utile ? Oui Non
Les plus utiles selon les utilisateurs :
- How could Java classes direct program messages to the system console, but error messages, say to a file?
- What are the differences between an interface and an abstract class?
- Why would you use a synchronized block vs. synchronized method?
- How can you force garbage collection?
- What are the differences between the methods sleep() and wait()?