EXECUTION

Detailed Initialization Procedure

12.4.2

because the class

Sub

 is never initialized; the reference to

Sub.taxi

 is a reference

to a field actually declared in class

Super

 and is not an active use of the class

Sub

.

Initialization of an interface does not, of itself, require initialization of any of

its superinterfaces. 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 initializa 

tion 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 actively used.

12.4.2   Detailed Initialization Procedure

Because Java 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

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