The term “super” appears in both Java and Python, but its function varies depending on the language and context. It’s essential for object-oriented programming, particularly when dealing with inheritance and class hierarchies.This article clarifies the use of “super” in both languages, covering constructors, method overriding, and generics.

‘super’ in Java: Constructors and Inheritance

In Java, “super” is primarily used to call the constructor of the parent class (also known as the superclass) from within a subclass. When a subclass is instantiated, the constructor of its superclass is also invoked. If you don’t explicitly call a superclass constructor using super(), Java automatically calls the no-argument constructor of the superclass [1]. However, if the superclass only defines constructors with arguments, you *must* explicitly call one of them using super(arguments).

“If you omit a call to the super constructor, the no-argument super constructor will be invoked automatically anyway.”

Consider this example:

class Animal {
    Animal(String name) {
        System.out.println("Animal constructor called with name: " + name);
    }
}

class Dog extends Animal {
    Dog(String name) {
        super(name); // Calling the Animal constructor with an argument
        System.out.println("Dog constructor called with name: " + name);
    }
}

public class Main {
    public static void main(String[] args) {
        Dog myDog = new Dog("Buddy");
    }
}
            

In this case, the Dog constructor explicitly calls the Animal constructor using super(name), passing the name to initialize the animal’s name. Without this explicit call, the code would fail to compile if the Animal class didn’t have a no-argument constructor.

‘super’ in Java: Generics

The keyword “super” also plays a role in Java generics, specifically with wildcard types. It’s used with the extends keyword to define upper and lower bounds for the types that a generic type can accept [3]. For example, List<? super Suit> indicates a list that can hold objects of type Suit or any of its superclasses.

This is particularly useful when you want to write to a list, ensuring that the objects you add are compatible with the list’s type.The list will accept the type of the object or any of its superclasses [3].

‘super’ in Python: Method Resolution Order (MRO)

In python, “super” is used to access methods of a parent class. It’s particularly useful in multiple inheritance scenarios, where the method resolution order (MRO) determines the order in which parent classes are searched for a method. Using super() ensures that methods are called in the correct order, following the MRO.

The super() function returns a proxy object that delegates method calls to a parent or sibling class. This is crucial for cooperative inheritance, where multiple classes in a hierarchy need to collaborate to initialize an object or perform an action.

Here’s a basic example:

class Animal:
    def __init__(self, name):
        self.name = name
        print("Animal initialized")

class Dog(Animal):
    def __init__(self, name, breed):
        super().__init__(name)
        self.breed = breed
        print("Dog initialized")

my_dog = Dog("Buddy", "Golden Retriever")
            

In this example, super().__init__(name) in the Dog class calls the __init__ method of the animal class, ensuring that the name attribute is initialized correctly. This is a common pattern for initializing inherited attributes.