Why can I override a protected method with public method?

java inheritance visibility overriding
Monstieur picture Monstieur · Apr 15, 2014 · Viewed 15.5k times · Source

The Java compiler doesn't complain when I override a protected method with a public method. What's really happening here? Is it overriding or hiding the parent method since the parent method has lower visibility?

Answer

Harmlezz picture Harmlezz · Apr 15, 2014

A sub-class can always widen the access modifier, because it is still a valid substitution for the super-class. From the Java specification about Requirements in Overriding and Hiding:

The access modifier (§6.6) of an overriding or hiding method must provide at least as much access as the overridden or hidden method, as follows:

  • If the overridden or hidden method is public, then the overriding or hiding method must be public; otherwise, a compile-time error occurs.
  • If the overridden or hidden method is protected, then the overriding or hiding method must be protected or public; otherwise, a compile-time error occurs.
  • If the overridden or hidden method has default (package) access, then the overriding or hiding method must not be private; otherwise, a compile-time error occurs.

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