Inheritance limitations in Java - Mini Project: Build & Apply

Understanding Inheritance Limitations in Java

📖 Scenario: You are learning about how Java inheritance works and its limitations. You will create simple classes to see what Java allows and what it does not allow when using inheritance.

🎯 Goal: Build a small Java program that demonstrates the limitation of Java inheritance: that a class cannot extend more than one class.

📋 What You'll Learn

Create a base class called Animal with a method sound() that prints "Animal sound".

Create another base class called Vehicle with a method move() that prints "Vehicle moves".

Try to create a class called AmphibiousCar that extends both Animal and Vehicle.

Observe the compilation error due to multiple inheritance limitation.

Create a class called Dog that extends only Animal and overrides sound() to print "Dog barks".

Create a main method to create a Dog object and call its sound() method.

💡 Why This Matters

🌍 Real World

Understanding inheritance limitations helps you design better Java programs and avoid errors when trying to reuse code.

💼 Career

Most Java developer jobs require knowledge of inheritance rules and how to use interfaces and composition to build flexible software.

1

Create the Animal class

Create a public class called Animal with a public method sound() that prints exactly "Animal sound".

Java

# Your code here

Need a hint?

Use System.out.println inside the sound() method to print the text.

2

Create the Vehicle class

Create a public class called Vehicle with a public method move() that prints exactly "Vehicle moves".

Java

public class Animal {
    public void sound() {
        System.out.println("Animal sound");
    }
}

# Your code here

Need a hint?

Similar to Animal, create a method move() that prints the required text.

3

Try to create AmphibiousCar extending both classes

Create a public class called AmphibiousCar that tries to extend both Animal and Vehicle using extends Animal, Vehicle. This will cause a compilation error due to Java's inheritance limitation.

Java

public class Animal {
    public void sound() {
        System.out.println("Animal sound");
    }
}

public class Vehicle {
    public void move() {
        System.out.println("Vehicle moves");
    }
}

# Your code here

Need a hint?

Java does not allow a class to extend more than one class. Writing extends Animal, Vehicle will cause an error.

4

Create Dog class extending Animal and test

Create a public class called Dog that extends Animal. Override the sound() method to print exactly "Dog barks". Then create a Main class with a main method that creates a Dog object and calls its sound() method.

Java

public class Animal {
    public void sound() {
        System.out.println("Animal sound");
    }
}

public class Vehicle {
    public void move() {
        System.out.println("Vehicle moves");
    }
}

// This class will cause a compilation error because Java does not support multiple inheritance
// public class AmphibiousCar extends Animal, Vehicle {
// }

# Your code here

Need a hint?

Override the sound() method in Dog to print "Dog barks". Then create a Dog object in Main.main and call sound().