Method declaration question

The question is
Which of the following statements are true?
a. If an accessible superclass method is static, then any method with the same signature in a subclass must also be static.
b. If a superclass method is synchronized, then the overriding method must also be synchronized.
c. If a superclass method is public, then the overriding method must also be public.
d. If a superclass method is native, then the overriding method must also be native.
e. If a superclass method is protected, then the overriding method must be protected or public.
The answers are a) c) and e)
Option a) is "If an accessible superclass method is static, then any method with the same signature in a subclass must also be static"
I am not able to understand the correctness of option a). Could anyone of you explain this?
What does signature mean? Does it include the return type, method name , paramaters and exceptions.

Hello Lakshmi,

"What does signature mean"

The JLS tells you...

8.4.2 Method Signature
The signature of a method consists of the name of the method and the number and types of formal parameters to the method.

So why is [a] correct? Because an instance method cannot override a static method. And why not? Because the term "override" really does not work here. A static method is a method without an instance context. If you would try to override such a method (without being static), you try to bring in an instance context, which the "overridden" method does not know. So it makes really no sense, because one cannot call it "overriding".
Hope it helps
Detlev

Hi Lakshmi,
I had written the code below, which helped in figure out why static methods are hidden and not overridden. It is a little long, but it was quite useful to me.
Thanks.

class Animal {
      int j = 50;
   
       static void staticMethod() {
         System.out.println("Animal's static method");
      }
   
       void instanceMethod() {
         System.out.println("Animal's instance method");
      }
   }
   
    class Dog extends Animal {
      int j = -10;
      
       static void staticMethod() {
         System.out.println("Dog's static method");
      }
   
       void instanceMethod() {
         System.out.println("Dog's instance method");
      }
   }
   
    class Understood_Static_Method_IS_Hidden
   {
       public static void main(String args[])
      {
         System.out.println("\n\nDog ch = new Dog();");
         Dog ch = new Dog(); //will refer to variables and methods of Dog
         System.out.println(ch.j);
         ch.staticMethod();
         ch.instanceMethod();
      
         System.out.println("\n\nAnimal pa = new Animal();");
         Animal pa = new Animal(); //will refer to variables and methods of Animal
         System.out.println(pa.j);
         pa.staticMethod();
         pa.instanceMethod();
      
         System.out.println("\n\nAnimal pc = new Dog();");
         Animal pc = new Dog();
         System.out.println(pc.j); //Animal's variable - animal reference cant see Dog's variable
         pc.staticMethod(); //Animal's method - static method not inherited
         pc.instanceMethod(); //Dog's method - non static method is inherited
      
         System.out.println("\n\nDog cp = (Dog) pc;");
         Dog cp = (Dog) pc; ////will refer to variables and methods of Dog
         System.out.println(cp.j);
         cp.staticMethod();
         cp.instanceMethod();
      }
   }

Thank you Detlev adn cathy.
Cathy thanks a lot for the code. I understood that Static methods are redefined and not overriden.
I also have another question. is overriding always concerned with Object methods instead of class methods'?

is overriding always concerned with Object methods instead of class methods'?

The basic principle behind overriding is ' A super class variable can refer a sub class object ' . i.e. Dynanic method dispatch - In overriding depends upon the object being referred corresponding method will be invoked. So, it should be concerned with object methods only.