Question

I’ve been reading a section on Statics in the SCJP study guide, and it mentions the following :

static methods can’t be overridden,
but they can be redefined

What does redefining actually mean? Is it a case of having a static method that exists in both parent and child, with the same signature, however they are referenced separately by their class names? Such as :

class Parent
{
   static void doSomething(String s){};
}

class Child extends Parent
{
   static void doSomething(String s){};
}

Referenced as : Parent.doSomething(); and Child.doSomething(); ?

Also, does the same apply for static variables, or just static methods?

Answer 1

It simply means that the functions are not virtual. As an example, say that you have an object of (runtime) type Child which is referenced from a variable of type Parent. Then if you invoke doSomething, the doSomething method of the Parent is invoked:

Parent p = new Child();
p.doSomething(); //Invokes Parent.doSomething

If the methods were non-static, doSomething of Child would override that of Parent and child.doSomething would have been invoked.

The same holds for static fields.