Problem Statement:

You are tasked with designing a system that adheres to the Liskov Substitution Principle (LSP) from the SOLID principles. The Liskov Substitution Principle states that objects of a superclass should be replaceable with objects of a subclass without affecting the correctness of the program. The goal is to create a system where derived classes can be used interchangeably with their base class without causing issues.

Solution:

1. Define a Base Class:

   public class Bird {
       public void fly() {
           System.out.println("The bird is flying.");
       }
   }

2. Create Derived Classes:

   public class Sparrow extends Bird {
       // Additional methods or overrides can be added
   }

   public class Penguin extends Bird {
       @Override
       public void fly() {
           System.out.println("Penguins cannot fly.");
       }
   }

3. Example Usage:

   public class Main {
       public static void main(String[] args) {
           Bird sparrow = new Sparrow();
           sparrow.fly();  // Outputs: "The bird is flying."
   
           Bird penguin = new Penguin();
           penguin.fly();  // Outputs: "Penguins cannot fly."
       }
   }