No, you cannot override a method in Java and make its access modifier more restrictive. This is a fundamental rule of method overriding.
Why Not?
The reason for this restriction is to preserve the principle of polymorphism and maintain consistent behavior when using objects of different classes in an inheritance hierarchy.
Let's illustrate with an example :
class Animal {
public void makeSound() {
System.out.println("Generic animal sound");
}
}
class Dog extends Animal {
// Valid override: Access modifier is the same (public)
@Override
public void makeSound() {
System.out.println("Woof!");
}
// Invalid override: Making the method more restrictive (public -> protected)
// @Override
// protected void makeSound() { // Compile-time error!
// System.out.println("Woof!");
// }
// Invalid override: Making the method more restrictive (public -> default)
// @Override
// void makeSound() { // Compile-time error!
// System.out.println("Woof!");
// }
// Invalid override: Making the method more restrictive (public -> private)
// @Override
// private void makeSound() { // Compile-time error!
// System.out.println("Woof!");
// }
}
public class Main {
public static void main(String[] args) {
Animal myAnimal = new Animal();
Animal myDog = new Dog(); // Polymorphism: Dog is an Animal
myAnimal.makeSound(); // Output: Generic animal sound
myDog.makeSound(); // Output: Woof! (Correctly calls Dog's makeSound)
}
}
The Problem:
If you were allowed to make the makeSound method in Dog protected, default, or private, the line myDog.makeSound() in the main method would cause a compile-time error. This is because the Animal reference myDog would no longer have access to the makeSound method in the Dog class. This would break the fundamental principle of polymorphism, which states that you should be able to treat a Dog object as an Animal object without any unexpected behavior.
The Rule:
The access modifier of an overridden method must be the same as or less restrictive than the access modifier of the method being overridden. In other words, you can widen the access (e.g., private -> default -> protected -> public), but you cannot narrow it. This rule ensures that polymorphism works correctly and that subclasses can be used interchangeably with their superclasses without causing access violations.