member interface

[Shiva Mohan]

Hi,

class ppp {
static class StaticNested { interface ABC {}} // 1
class NonStaticInner {interface DEF {}} // 2
interface GHI {} // 3
}
A compile-time error is generated at which line?

a. 1
b. 2
c. 3
d. None of the above

Answer is b as member interface is implicitly static.But I would say option c also will give compile time error.

I verified the java language specification that says

    
class HasStatic{
static int j = 100;
}
class Outer{
class Inner extends HasStatic{
static final x = 3;// ok - compile-time constant
static int y = 4; // compile-time error, an inner class
}
static class NestedButNotInner{
static int z = 5; // ok, not an inner class
}
interface NeverInner{}// interfaces are never inner
}

Please clarify my doubt.

[Barry Gaunt]

If you remove line 2 from your code it compiles without problems. So option c) is wrong.

If nested interfaces are implicitly static, then it means that line 3 is the same as:

[B]static[/B] interface GHI {} // 3

which compiles without problems.

The JLS example is a little misleading. The code

class Outer{
 
interface NeverInner{}// interfaces are never inner
}    

compiles. The interface NeverInner is not an "inner" interface (there is no such thing), it is a "static nested" or "nested" interface.

[wise owen]

There is no such thing as an inner interface. Because, interfaces are always implicitly static. They are always top-level, not inner. Inner classes cannot have any static modifiers at all.

    
interface Outer { // Top-level interface
   interface Inner {// top-level nested interface 
   }
}
 
class Outer
class Inner { 
 
/* This will cause an error. Becuase, you can not define a static modifier 
   inside an inner class. Inner is an inner class and InnerInterface is  
   implicitly static. Compiler will complain. 
*/ 
   interface InnerInterface {//ERROR!
   }
}

[Shiva Mohan]

Thankyou very much.now i got the misleading.