abstract interface

[Anonymous]

I've been using the SCPJ2(exam 310-025) for a study guide. I like the layout but the number of incorrect stmts and mock answers is to much to stand.
Anyway, one of the claims in the book is that an interface can't be declared as abstract. However, I compiled and ran the code below with no problem.(JBuilder 3) Anyone have a definitive answer on this??
abstract interface next
{
public final static int test = 4;
public void foo(int j);
}

public class examprep implements next
{
public examprep()
{
}
public void foo(int j)
{
}
public static void main(String[] args)
{
examprep instance = new examprep();
instance.foo(3);
}
}

[kking]

The answer that I can give is that interfaces are implicitly abstract and hence have no need to be explicitly stated as such. The reason for this is that their methods must be abstract.