The Java Language Specification, Third Edition

EXECUTION Detailed Initialization Procedure 12.4.2
Thus, the test program:
interface I {
int i = 1, ii = Test.out("ii", 2);
}
interface J extends I {
int j = Test.out("j", 3), jj = Test.out("jj", 4);
}
interface K extends J {
int k = Test.out("k", 5);
}
class Test {
public static void main(String[] args) {
System.out.println(J.i);
System.out.println(K.j);
}
static int out(String s, int i) {
System.out.println(s + "=" + i);
return i;
}
}
produces the output:
1
j=3
jj=4
3
The reference to J.i is to a field that is a compile-time constant; therefore, it
does not cause I to be initialized. The reference to K.j is a reference to a field
actually declared in interface J that is not a compile-time constant; this causes initialization
of the fields of interface J, but not those of its superinterface I, nor
those of interface K. Despite the fact that the name K is used to refer to field j of
interface J, interface K is not initialized.
DRAFT
12.4.2 Detailed Initialization Procedure
Because the Java programming language is multithreaded, initialization of a class
or interface requires careful synchronization, since some other thread may be trying
to initialize the same class or interface at the same time. There is also the possibility
that initialization of a class or interface may be requested recursively as
part of the initialization of that class or interface; for example, a variable initializer
in class A might invoke a method of an unrelated class B, which might in turn
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