Friday 24 May 2013

JAVA INTERVIEW QUESTIONS - Access Specifiers

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38.What are Access Specifiers?

One of the techniques in object-oriented programming is encapsulation. It concerns the hiding of data in a class and making this class available only through methods. Java allows you to control access to classes, methods, and fields via so-called access specifiers..

39.What are Access Specifiers available in Java?
Java offers four access specifiers, listed below in decreasing accessibility:
  • Publicpublic classes, methods, and fields can be accessed from everywhere.
  • Protectedprotected methods and fields can only be accessed within the same class to which the methods and fields belong, within its subclasses, and within classes of the same package.
  • Default(no specifier)- If you do not set access to specific level, then such a class, method, or field will be accessible from inside the same package to which the class, method, or field belongs, but not from outside this package.
  • Privateprivate methods and fields can only be accessed within the same class to which the methods and fields belong. private methods and fields are not visible within subclasses and are not inherited by subclasses.

 Situation  public  protected  default  private 
 Accessible to class
 from same package? 
yesyesyesno
 Accessible to class
 from different package? 
yes no, unless it is a subclass nono



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