Prev Next

Java Inheritance

Inheritance in Java is a mechanism where one class acquires the properties (fields) and behaviors (methods) of another class. It allows for hierarchical classification and promotes code reusability.

1. Types of Inheritance

  • Single Inheritance: A class inherits from one superclass.
  • Multilevel Inheritance: A class inherits from a subclass, forming a hierarchy.

Note: Java does not support multiple inheritance with classes (a class cannot inherit from more than one class).

2. Syntax

Use the extends keyword to inherit from a class.

public class SuperClass {
    // Superclass code
}

public class SubClass extends SuperClass {
    // Subclass code
}

3. Example

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

public class Dog extends Animal {
    public void bark() {
        System.out.println("Barking...");
    }
}

public class Main {
    public static void main(String[] args) {
        Dog dog = new Dog();
        dog.eat();  // Inherited from Animal class
        dog.bark(); // Defined in Dog class
    }
}

4. Method Overriding

Subclass can override methods of the superclass to provide specific implementation.

public class Animal {
    public void makeSound() {
        System.out.println("Some generic animal sound");
    }
}

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

5. The super Keyword

The super keyword refers to the superclass and is used to access superclass methods and constructors.

6. Key Takeaways

  • Inheritance promotes code reusability and hierarchical classification.
  • Use the extends keyword to inherit from a superclass.
  • Method overriding allows subclasses to provide specific implementations.
  • The super keyword accesses superclass members.
  • Understand the inheritance hierarchy to design effective class structures.
Prev Next