Nested interfaces implicitly static?

[marc weber]

My code below appears to demonstrate that nested interfaces are implicitly static. First, note that the compiler treats the nested interface as a static context; and second, the nested interface can be implemented without an instance of the enclosing class (even outside of that class).

Is this documented anywhere? The Java Language Specifications state that interfaces can be a members of a class, but I couldn't find anything saying that they're implicitly static.

public class EnclosingClass{
  int a = 3;
  static int b = 5;
 
  //apparently, nested interface is IMPLICITLY static
  interface NestedInterface{
    //int c = a;//error - non-static var referenced from static context
    int d = b;
    void interMethod();
  }
 
  static class NestedClass implements NestedInterface{
    //int e = a;//error, as expected in static context
    int f = b;
    public void interMethod(){
      System.out.println("NestedClass.interMethod(): " + b + d + f);
    }
  }
 
  public static void main(String[] args){
    //no instance of EnclosingClass created...
    EnclosingClass.NestedClass x = new NestedClass();
    x.interMethod();
    OtherClass y = new OtherClass();
    y.interMethod();
  }
}
 
//can implement nested interface without instance of EnclosingClass...
class OtherClass implements EnclosingClass.NestedInterface{
  public void interMethod(){
    System.out.println("OtherClass.interMethod(): " + d);
  }
}

[marc weber]

Oh, I just found it:

"Member interfaces ... are always implicitly static..."

Ref: http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#262890

(Well, that was a nice exercise anyway.)

:roll:
[ September 24, 2004: Message edited by: marc weber ]

[Alan Moore]

http://www.absolutejava.com/main-articles/java-tidbits/

The "Modifier Restrictions" section of that page might interest you.

[marc weber]

Interesting page... Nice and concise. Thanks!