Why Does Java Restrict `super.super.method()` Access?

Why Restricting super.super.method() Enforces Encapsulation in Java

In Java, attempting to access a method of the grandparent class through super.super.method() triggers a compilation error. This restriction serves a crucial purpose by upholding encapsulation principles.

In object-oriented programming, encapsulation limits access to the internals of a class, ensuring that the class's behavior remains well-defined and consistent. Subclasses inherit the properties and methods of their superclasses, but these methods are meant to be extended or overridden rather than bypassed.

Consider a scenario where a base class (Collection) defines an add method for adding elements. A subclass (RedCollection) overrides this method to ensure that only red elements are added. However, if it were possible to call super.super.add(), a rogue subclass (NaughtyCollection) could bypass the red filter by directly invoking the base class's add method, thereby breaking the invariant maintained by RedCollection.

This restriction prevents such violations of encapsulation, ensuring that subclasses can only manipulate the behavior inherited from their parent classes as intended. It maintains class cohesion and prevents unexpected method invocations that could compromise the integrity of the class.

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