how to initialize static final variable from other class in java

Question

I want to initialize Final.value in Main method. Is it possible to initialize static final constant in other class than in its deceleration class?

public class Main {

    public static void main(String[] args) {
        //I want to initialize Final.value in Main method.
    }

}

class Final {
    //here is the static final variable which can be assigned vai a static block
    //but how do I initialize it in the main method if I don't use the static block?
    static final int value;


}

Well that's the purpose of ```final```. Not to be able to set it again after it was set once. — D. Lawrence, Jan 16 '20 at 19:06
You don't need the initializer block, just do it in-line `static final int value = 421` — Michael, Jan 16 '20 at 19:08
You can probably do it using complicated reflection, but is it worth it? https://stackoverflow.com/a/3301720/12609572 — ardenit, Jan 16 '20 at 19:10
@D.Lawrence I have edited the question were it is not initialized. Now how do I initialize it in other class? — SHOONYA, Jan 16 '20 at 19:11
@SHOONYA You can't even have a class like that for `Final`, try it yourself...disregarding any other class your `Final` will not compile in the current state. — Nexevis, Jan 16 '20 at 19:14

score 0 · Answer 1 · answered Jan 16 '20 at 19:15

0

You cannot. Your perception might be that main happens before everything else, so it is safe to initialise things there, but that is incorrect.

Consider the following code.

class Scratch
{
    static
    {
        System.out.println(Foo.i);    
    }

    public static void main(String[] args)
    {
        Foo.i = 100;
    }
}

class Foo
{
    static int i;
}

It does not print 100. It prints 0 because there are other things which happen before main.

Making the field final does not change that fact.

You have two options for static initialization. In a static initializer block, like you showed, or in-line:

static final int value = 421

Java prevents you from doing what you want to do for a good reason: because it is likely to lead to bugs.

answered Jan 16 '20 at 19:15

Michael

41,989
11
82
128

But is there a way to initialize it in any other class than its deceleration class ? – SHOONYA Jan 16 '20 at 19:18
@SHOONYA No. You can modify the field value from another class, but in which case it cannot be `final`, and cannot be considered to be a constant. – Michael Jan 16 '20 at 19:20
Note, you can initialise it _using_ another class (by calling a method from another class, e.g. `private static final int x = SomeClass.computeX();`). – BeUndead Jan 16 '20 at 19:25

how to initialize static final variable from other class in java

1 Answers1