Static method overriding in Java [duplicate]

Question

class B extends A { static public void printMe(){ System.out.println("in static B"); } } class A{ static public void printMe(){ System.out.println("In static A"); } } public static void main(String[] args) { A a = new B(); a.printMe(); }

Why is the output "In static A" ?

Consequence: don't use static: use a singleton if you need only one instance (of course the singleton implementation may use static inside) — pdem
– pdem, Commented Jan 10, 2018 at 10:31
Related / duplicate: Is it possible to override a static method in derived class? — Bernhard Barker
– Bernhard Barker, Commented Jan 10, 2018 at 10:33
There is a reason why you should never call a static method on an "object instance" - you should just say A.printMe() or B.printMe(). I consider Java allowing to call static methods on an instance an error in the language specs... — Gyro Gearless
– Gyro Gearless, Commented Jan 10, 2018 at 10:34

Suresh Atta · Accepted Answer · 2018-01-10 10:29:58Z

4

Static members bind to type rather than implemented type. Hence you see the methods executing from class A.

And static members are not to be ovverriden and they share same copy regardless of instance state.

If you need methods to be ovveriden, do not use them as static members.

answered Jan 10, 2018 at 10:29

Suresh Atta

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3 Comments

Stultuske Over a year ago

"static members are not to be overridden". They can't be overridden. They can be 'hidden' by a new static implementation in the child class, though.

Suresh Atta Over a year ago

True. Stressing only about overriding.

Stultuske Over a year ago

I understand, but sometimes people assume that if you can put a static method with the same signature in a child class, it means it has been overridden. Causes quite a lot of mistakes

jitin rathi · Accepted Answer · 2018-01-10 10:51:45Z

Static member or method belongs to class level instead of specific instance.

A static class will have only 1 instance even if you create multiple instance or do not create instance.

In your case, since you have created instance of class A, method inside class A is implemented.

Another way to get a clear concise for the problem scenario is try running the code mentioned below:

public static void main(String[] args) { A.printMe(); }

You will get clear idea.

the point is: the instance is of B, it's the declaration that limits it to an A.

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