Extends vs. Implements: When to Use Inheritance and Interface Implementation?

Implements vs Extends: A Breakdown

In object-oriented programming, the concepts of "implements" and "extends" play a crucial role in class and interface relationships. Let's delve into the differences between these two keywords to understand when and how to use them effectively.

Extends

The "extends" keyword is used to derive a new class (subclass) from an existing class (superclass). This relationship establishes an inheritance hierarchy where the subclass inherits the properties and methods of its superclass. By extending a class, you create a 'child' class that inherits the behavior of the 'parent' class.

Implements

In contrast, the "implements" keyword is used when a class implements an interface. An interface defines a set of methods without providing any implementation. By implementing an interface, a class contracts to provide implementations for each of the interface's declared methods. Unlike classes, interfaces cannot be instantiated.

Key Differences

Inheritance: Extends establishes inheritance, while implements does not.
Method Implementation: In inheritance, methods are inherited and can be overridden in the subclass. In implementation, methods must be implemented by the class that implements the interface.
Instantiation: Classes can be instantiated, but interfaces cannot.

Uses and Benefits

Extends:

• For creating specialized subclasses that inherit the functionality of their superclass.
• To extend or modify existing class behavior.
• To create a hierarchy of classes with different levels of functionality.

Implements:

• For implementing the methods specified by an interface.
• To enforce that a class provides specific behavior defined in the interface.
• To define contracts between different classes and modules.

By understanding the distinction between "extends" and "implements," you can utilize them correctly to structure your code effectively and enhance its maintainability and flexibility.

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