polymorphism - Why can't you reduce the visibility of a method in a Java subclass?

Question

Why does the compiler give an error message when you reduce the visibility of a method while overriding it in the subclass?

question from:https://stackoverflow.com/questions/1600667/why-cant-you-reduce-the-visibility-of-a-method-in-a-java-subclass

Answer 1

Because every instance of the subclass still needs to be a valid instance of the base class (see Liskov substitution principle).

If the subclass suddenly has lost one property of the base class (namely a public method for example) then it would no longer be a valid substitute for the base class.