Q. interface definitions

[Karin Paola Illuminate]

Can someone tell me why answer C is not correct? Thanks.

[ 13 ] Which of the following interface definitions are legal? (Choose Two.) 
 
  A. public interface A {int a();} 
 
  B. public interface B implements A {} 
 
  C. interface C {int a;} 
 
  D. private interface D {} 
 
  E. abstract interface E {} 
 

[Bagnall, ExamSim]

[Reshma Shanbhag]

Karin,
Any member variables declared within an Interface are Implicitly public, static and final. The complier complains when you dont initialize the final variables.
Hence in option (c)
when you declare 'int c' it is equivalent to 'public static final int c' and since it is not initialized complier will complain. Hence option 'c' is not right.
Hope this helped you
Reshma

[Ravi Anamalay]

So is the answer to the question A & E ?

[Karin Paola Illuminate]

Thanks.
So,
A. public interface A {int a();}
Ok. The methods in an interface are all abstract.
B. public interface B implements A {}
Not Ok. Interfaces can only extend other interfaces (not implement).
C. interface C {int a;}
Not Ok.
D. private interface D {}
Not Ok.
E. abstract interface E {}
Ok. An interface is already abstract implicitly, but can be declared abstract.
So, interfaces may not declare variables unless they are initialized?
I believe that is also true for classes. Classes may not declare variables as final unless they are initialized. But, that doesn't seem to be true for "local variables or automatic variables". Am I correct?