Java: determine if a static method is called from an instance or statically

Question

In Java, is it possible to determine whether a static method is called from either an instance of the object, or statically (SomeClass.method())?

To give you an a better idea of what I'm talking about, take look at this code below:

public class SomeClass {

    public static void staticMethod() {

        if (/*called from instance*/) {
            System.out.println("Called from an instance.");
        } else if (/*called statically*/){
            System.out.println("Called statically.");
        }
    }

    public static void main(String[] args) {
        new SomeClass().staticMethod();//prints "Called from an instance."
        SomeClass.staticMethod();//prints "Called statically."
    }

}

I understand it isn't good practice to call a static method from an instance, but still, is it possible to differentiate between these two calls? I was thinking that the Reflection API probably holds the key to this.

Thats not possible, it compiles to exactly the same bytecode. — tkausl, Jun 24 '16 at 03:17
No. As far as I know, the two calls compile to exactly the same bytecode. (And @tkausl wins by 14 seconds) — ajb, Jun 24 '16 at 03:17
You should really ask yourself why you think you need that (and if there is not a better way to achieve whatever the real task is). — Thilo, Jun 24 '16 at 03:34

score 1 · Accepted Answer · edited May 23 '17 at 12:33

1

That is not possible by just calling the method. However you can gain some useful information from the stacktrace explained here How do I find the caller of a method using stacktrace or reflection?

This will allow you to determine the method name and/or caller class using the static method

edited May 23 '17 at 12:33

Community

1
1

answered Jun 24 '16 at 03:21

Rohan Verma

26
3

Not really an answer. – shmosel Jun 24 '16 at 03:22
ok. editted to directly say its not possible which is an answer. – Rohan Verma Jun 24 '16 at 03:24
In the example, the caller class/method name would be identical for both cases, though. – Thilo Jun 24 '16 at 03:38

score 1 · Answer 2 · answered Jun 24 '16 at 03:38

1

I don't think reflection can make this. But, you can make it in another way:

public class SomeClass {

    public static void staticMethod(boolean isStaticCall) {

        if (!isStaticCall) {
            System.out.println("Called from an instance.");
        } else{
            System.out.println("Called statically.");
        }
    }

    public static void main(String[] args) {
        new SomeClass().staticMethod(false);//prints "Called from an instance."
        SomeClass.staticMethod(true);//prints "Called statically."
    }

}

answered Jun 24 '16 at 03:38

expoter

1,622
17
34

1

The caller could lie about it, though. – Thilo Jun 24 '16 at 03:38
Absolutely! Anyway, java program will never be strong enough. Eg: private inner class. – expoter Jun 24 '16 at 03:42

Java: determine if a static method is called from an instance or statically

2 Answers2