Java Inheritance and the super Keyword

Welcome! In this part, we'll focus on inheritance in object-oriented programming (OOP) with Java. Inheritance allows us to share code across classes, thereby enhancing readability and efficiency.

In this lesson, we'll clarify attribute and method inheritance in Java through practical examples. Our lesson's outline includes defining inheritance, exploring attribute inheritance, understanding method inheritance, and decoding the super keyword in Java. Ready? Let's get started!

Inheritance in Java involves creating a subclass that inherits attributes and methods from a superclass. In Java, many scenarios allow classes to share common attributes or methods, making inheritance very useful.

The extends keyword is used to set up inheritance, allowing one class to inherit properties and methods from another class. Here's an example featuring a superclass named Vehicle and a subclass named Car:

// Define the superclass 'Vehicle'
class Vehicle {
    // Initialize the Vehicle with color and brand attributes
    private String color;
    private String brand;

    public Vehicle(String color, String brand) {
        this.color = color;
        this.brand = brand;
    }

    public String getColor() {
        return color;
    }

    public String getBrand() {
        return brand;
    }
}

// Define the subclass 'Car', inheriting from 'Vehicle'
class Car extends Vehicle {
    private int doors;

    public Car(String color, String brand, int doors) {
        super(color, brand);
        this.doors = doors;
    }

    public int getDoors() {
        return doors;
    }
}

public class Solution {
    public static void main(String[] args) {
        Car myCar = new Car("Red", "Toyota", 4);
        System.out.println("Color: " + myCar.getColor()); // Output: Color: Red
        System.out.println("Brand: " + myCar.getBrand()); // Output: Brand: Toyota
        System.out.println("Doors: " + myCar.getDoors()); // Output: Doors: 4
    }
}

In the Car class, the super() constructor within its constructor calls the Vehicle class's constructor, ensuring that inherited properties are initialized correctly. The extends keyword indicates that Car is a subclass of Vehicle.

Our focus in this lesson is primarily on single inheritance, where one superclass is extended by a single subclass.