Question

What are the differences and similarities of EXTENDS and interface ":" inheritance?

Short answer

EXTENDS and Interfaces both promote code reusability. EXTENDS achieves this by enabling one class to inherit the properties and methods of another, allowing multiple subclasses to share these traits. On the other hand, interfaces enforce the implementation of certain methods in any class that implements the given interface. The key difference is that a class can extend only one other class but can implement multiple interfaces.

Step-by-step solution

Defining EXTENDS and Interfaces

EXTENDS is used in class declarations or class expressions to create a class as a child of another class. An Interface in programming, however, is a blueprint of a class. It has static constants and abstract methods.

Understanding the Similarities

Both EXTENDS and interfaces promote reusability of the code. They both provide a way to achieve abstraction and multiple inheritance in the code.

Listing the Differences between EXTENDS and Interfaces

Difference can be understood by the following points: \n1. EXTENDS is used to inherit properties and methods from one class to another, while interfaces are used to implement methods in a class which are declared in an interface.\n2. With EXTENDS, a class can only extend one other class, while it can implement multiple interfaces.\n3. EXTENDS allows for the creation of methods in a superclass that can be shared among multiple subclasses, while an interface only allows for the declaration of methods that must be implemented in any class that implements the interface.

Key concepts

Inheritance

Inheritance is a core concept in object-oriented programming that allows one class, referred to as a subclass, to inherit the properties and methods from another class, called the superclass. This means that the subclass can use or override the features of the superclass.
The main purpose of inheritance is to create a new class from an existing class. Thus, it aids in code reusability because instead of writing new code, you can use existing code by extending a class.
With inheritance, classes are organized hierarchically. This makes the code structure more straightforward and easier to manage. For example, if there are several classes that share common features, they can inherit from a common superclass to minimize redundancy.

• Reduces duplication in code
• Enhances maintainability
• Promotes cleaner code

Interfaces

An interface in object-oriented programming acts as a contract between the class and the outside world. By implementing an interface, a class agrees to perform specific behaviors outlined in the interface, like a promise to follow certain rules.
Interfaces help in defining methods that can be used across multiple classes for uniformity without having to define how these methods work. This allows for flexibility and scalability in the program.

• An interface contains method declarations without concrete implementations
• A class can implement multiple interfaces, thus achieving multiple inheritances
• Promotes consistent behavior across different classes

While class inheritance allows for a class to extend only one superclass, it can implement multiple interfaces, enabling more versatile programming structures.

Abstraction

Abstraction simplifies complex systems by hiding the unnecessary details and showing only the essential attributes of objects. This means concentrating on what an object does instead of how it does it.
In programming, abstraction can be achieved through interfaces and abstract classes. For instance, interfaces define methods that must be implemented, focusing on the "what" rather than the "how." This helps in managing more complicated problems, allowing the programmer to think conceptually about a problem rather than getting lost in the details.

• Focus is on what an object does
• Hides complex realities with a simpler interface
• Facilitates higher-level thinking

Abstraction aids in reducing complexity and increasing efficiency by creating layers. Each layers handles its operations and exposes a simple interface.

Code Reusability

In object-oriented programming, code reusability refers to the capability to use existing code in new situations or applications, which minimizes redundancy and enhances productivity. Inheritance and interfaces are vital tools for achieving code reusability.
Using inheritance, you can create new classes by extending existing ones. This ensures that the new class takes on the properties and behaviors of the existing class. With interfaces, multiple classes can follow a specific method structure, allowing disparate classes to execute similar functionalities.

• Decreases development time and effort
• Promotes consistency in code
• Improves software maintenance and extendability

The main benefit of code reusability is in driving down development and maintenance costs, while also ensuring that the codebase remains consistent and easier to update or troubleshoot.