Taking Code Further: Inheritance and Polymorphism

In Java, you can create new classes that build on existing ones—this is called inheritance. It helps you avoid repeating code. Polymorphism lets you treat objects of different classes in the same way if they share a common ancestor.

How Inheritance Works

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

public class Cat extends Animal {
  void speak() {
    System.out.println("Meow");
  }
}

Here, Cat inherits from Animal but can override the speak() method.

Polymorphism in Action

Animal myPet = new Cat();
myPet.speak(); // Output: Meow

The program knows to call the Cat version of speak()!

Real-World Impact

• Video games use inheritance for different types of enemies.
• Banking apps use polymorphism for different kinds of accounts.

Tips

• Use extends to inherit.
• Use @Override to show when you override a method.