Why static block is not executed

Question

As per java doc, static block is executed when the class is initialized.

Could anyone please tell me why static block is not executed when I run below code?

class A {
    static {
        System.out.println("Static Block");
    }
}

public class Main {

    public static void example1() {
        Class<?> class1 = A.class;
        System.out.println(class1);
    }


    public static void example2() {
        try {
            Class<?> class1 = Class.forName("ClassLoading_Interview_Example.ex1.A");
            System.out.println(class1);
        }catch(Exception e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        example1();
    }
}

arxakoulini · Accepted Answer · 2018-03-16T11:34:24.710

5

A class's static initialization normally happens immediately before the first time one of the following events occur:

an instance of the class is created,

a static method of the class is invoked,

a static field of the class is assigned,

a non-constant static field is used, or [...]

You are currently not doing any of the above. So, by replacing

Class<?> class1 = A.class;
System.out.println(class1);

with this for example

A object = new A();

will give you your result.

edited Mar 16 '18 at 11:34

answered Mar 16 '18 at 11:28

arxakoulini

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22

So what happens when i execute this line "Class> class1 = A.class;". Would not the JVM load class A? – Sridhar Srinivasan Mar 16 '18 at 14:33
@SridharSrinivasan If you execute this line the JVM will load the class, but will not initialize it as a class initialization happens according to a set of rules (see my quote above) and this is not included in those rules. – arxakoulini Mar 16 '18 at 16:31

xingbin · Answer 2 · 2018-03-16T11:44:09.587

Referencing A.class will not resulting in executing A's static initializers, see here

Initialization of a class consists of executing its static initializers and the initializers for static fields (class variables) declared in the class.

And

A class or interface type T will be initialized immediately before the first occurrence of any one of the following:

T is a class and an instance of T is created.

A static method declared by T is invoked.

A static field declared by T is assigned.

A static field declared by T is used and the field is not a constant variable (§4.12.4).

Why static block is not executed

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