12.4.1

When Initialization Occurs

EXECUTION

Before a class is initialized, its superclasses are initialized, if they have not

previously been initialized.

Thus, the test program:

class Super {

static { System.out.print("Super "); }

}

class One {

static { System.out.print("One "); }

}

class Two extends Super {

static { System.out.print("Two "); }

}

class Test {

public static void main(String[] args) {

One o = null;

Two t = new Two();

System.out.println((Object)o == (Object)t);

}

}

prints:

Super Two false

The class

One

 is never initialized, because it not used actively and therefore is

never linked to. The class

Two

 is initialized only after its superclass

Super

 has

been initialized.

A reference to a field is an active use of only the class or interface that actu 

ally declares it, even though it might be referred to through the name of a subclass,

a subinterface, or a class that implements an interface. The test program:

class Super { static int taxi = 1729; }

class Sub extends Super {

static { System.out.print("Sub "); }

}

class Test {

public static void main(String[] args) {

System.out.println(Sub.taxi);

}

}

prints only:

1729

224