The terms ‘super’ and ‘extends’ are fundamental concepts in object-oriented programming, particularly in languages like Java and Python. They play crucial roles in inheritance and code reusability. While ‘super’ is used in both languages, ‘extends’ is specific to Java and relates to class inheritance and generics.

‘super’ Keyword

The ‘super’ keyword is used to call methods or constructors from a parent class. it’s a way for a subclass to access and utilize functionality already defined in it’s superclass, promoting code reuse and avoiding redundancy.

in Python, ‘super’ is commonly used within the __init__ method of a subclass to properly initialize the parent class. This ensures that the parent class’s initialization logic is executed before any subclass-specific initialization. The correct usage of ‘super’ in Python involves passing the subclass and the instance as arguments [[2]].

Enforcing super to appear first, enforces that constructor bodies are executed in the correct order.

In Java, ‘super’ is used similarly to call a parent class’s constructor or method. When used in a constructor, super() must be the first statement.This ensures that the parent class is initialized before the child class [[3]].

‘extends’ keyword in Java

The ‘extends’ keyword in Java is used to create a subclass (child class) from another class (parent class). This establishes an inheritance relationship, where the subclass inherits the properties and methods of the superclass. It’s a core mechanism for achieving inheritance in Java.

In the context of Java Generics, ‘extends’ is also used to specify an upper bound for the types that a generic type can accept. for example, <T extends number> indicates that the type T must be a subclass of Number.

Difference in Java Generics: ‘super’ vs ‘extends’

In Java Generics,both ‘super’ and ‘extends’ are used to define type constraints,but they serve different purposes. <? extends T> defines an upper bound, meaning the type can be T or any subtype of T. <? super T> defines a lower bound, meaning the type can be T or any supertype of T. Understanding the mechanical difference between these two is crucial for effective use of generics [[1]].