Why inheritance is used in Java - See It in Action

Why inheritance is used

📖 Scenario: Imagine you are creating a program for a zoo. You want to represent different animals, but many animals share common features like having a name and age. Instead of writing the same code again and again, you can use inheritance to share these common features.

🎯 Goal: Build a simple Java program that shows how inheritance helps reuse code by creating a base class Animal and a derived class Dog that inherits from Animal.

📋 What You'll Learn

Create a base class called Animal with variables name and age

Create a derived class called Dog that inherits from Animal

Add a method displayInfo() in Animal to print the animal's name and age

In Dog, add a method bark() that prints a barking message

Create an object of Dog and call both displayInfo() and bark()

💡 Why This Matters

🌍 Real World

Inheritance is used in many programs to organize code and avoid repetition, like in games, apps, and websites.

💼 Career

Understanding inheritance is important for software developers to write clean, reusable, and maintainable code.

1

Create the base class Animal

Create a class called Animal with two variables: String name and int age. Add a constructor that sets these variables.

Java

class Animal {
    // Your code here
}

Need a hint?

Use a constructor to set name and age when creating an Animal.

2

Add a method to display animal info

Inside the Animal class, add a method called displayInfo() that prints the animal's name and age using System.out.println.

Java

class Animal {
    String name;
    int age;

    Animal(String name, int age) {
        this.name = name;
        this.age = age;
    }

    // Your code here
}

Need a hint?

Use System.out.println("Name: " + name + ", Age: " + age); inside displayInfo().

3

Create Dog class that inherits from Animal

Create a class called Dog that extends Animal. Add a constructor in Dog that calls the Animal constructor using super(name, age). Add a method bark() that prints "Woof!".

Java

class Animal {
    String name;
    int age;

    Animal(String name, int age) {
        this.name = name;
        this.age = age;
    }

    void displayInfo() {
        System.out.println("Name: " + name + ", Age: " + age);
    }
}

// Your code here

Need a hint?

Use extends Animal to inherit. Use super(name, age) in the constructor.

4

Create Dog object and call methods

In the main method, create a Dog object with name "Buddy" and age 3. Call the displayInfo() and bark() methods on this object.

Java

class Animal {
    String name;
    int age;

    Animal(String name, int age) {
        this.name = name;
        this.age = age;
    }

    void displayInfo() {
        System.out.println("Name: " + name + ", Age: " + age);
    }
}

class Dog extends Animal {
    Dog(String name, int age) {
        super(name, age);
    }

    void bark() {
        System.out.println("Woof!");
    }
}

public class Main {
    public static void main(String[] args) {
        // Your code here
    }
}

Need a hint?

Create the Dog object with new Dog("Buddy", 3). Call displayInfo() and bark().