protected can not be accessed in derived ??

[JigaR Parekh]

why protected can not be accessed in derived class.

  
//in file A.java
package p1;
public class A
{
      protected int i = 10;
      public int getI() { return i; }
}
//in file B.java
package p2;
import p1.*;
public class B extends p1.A
{
   public void process(A a)
   {
      a.i = a.i*2;
   }
   public static void main(String[] args)
   {
      A a = new B();
      B b = new B();
      b.process(a);
      System.out.println( a.getI() );
   }
}
 

Select 1 correct option.

a It will print 10.
b It will print 20.
c It will not compile.
d It will throw an exception at Run time.
e None of the above

I have selected answer b but correct answer is c why ???

[Steve Morrow]

Protected access can be tricky. You can only access protected members from within the context of the inherited class. For instance, you can access B's 'i' variable (inherited from A), but not A's through an A reference, since B is in a separate package.

From the JLS:

�6.6.2 Details on protected Access
A protected member or constructor of an object may be accessed from outside the package in which it is declared only by code that is responsible for the implementation of that object.

Hope this helps!

[JigaR Parekh]

thx for explanation

[Smitha Ballikar]

hi,

I didnt understand the explanation. Can somebody explain why answer is not 20.

Cheers
Smitha

[Steve Morrow]

The answer is not 20, as the B class is not allowed access to A's i variable. It's outside the package, and the code that attempts to access the i variable is not responsible for the implementation of the A type.

[Ryan Kade]

Here's my take on it as well:

http://www.coderanch.com/t/250316/java-programmer-SCJP/certification/Confused-protected-modifier

[Smitha Ballikar]

Thanks!! Got it now..

[srikanth reddy]

thanks parekh ...

nice question


thanks & regards

srikanth reddy