Question

Isn’t that subclass inherits everything from superclass true? But subclass could not access its superclass’s private attribute/method, but can access its own. So I wrote a test program. But it seems subclass has not one!

class a {
    private void set() {
           System.out.println("a.set()");
    }
}
public class b extends a {
//      private void set() {
//      System.out.pritln("b.set()");
//       }
        void f() {
             set();
        }
        public static void main(String[] args) {
             b b = new b();
             b.f();
        }
}

If I comment out the set() method in b as the example does, it won’t compile.

Any idea? Any explanation from JVM view ?

Answer 1

Yes, private methods aren’t accessible from a derived class. protected and public are.

When you declare set in your derived class, you gain access to this derived version since it’s now part of the class (no longer a private base class method).

You’d still get an error if you attempted to call super.set().

Edit: the trick aroth’s talking about I assume is reflection. 🙂 Don’t.