Inheritance

Inheritance is a fundamental concept in object-oriented programming (OOP) that allows you to create new classes (subclasses) that inherit properties and behaviors from existing classes (superclasses). There are several types of inheritance in Java:

1. Single Inheritance:

   • In single inheritance, a subclass can inherit from only one superclass.
   • Java supports single inheritance for classes, which means a class can have only one direct parent class (superclass).
   • This is the most common form of inheritance and ensures a simple and straightforward class hierarchy.

   class Animal {
       // ...
   }
   
   class Dog extends Animal {
       // ...
   }

2. Multiple Inheritance (Not Supported in Java):

   • Multiple inheritance allows a class to inherit properties and behaviors from more than one superclass.
   • Java does not support multiple inheritance for classes due to the "diamond problem," which can result in ambiguity when resolving method calls.
   • However, Java supports multiple inheritance through interfaces, where a class can implement multiple interfaces to inherit behavior from different sources.

   interface A {
       // ...
   }
   
   interface B {
       // ...
   }
   
   class MyClass implements A, B {
       // ...
   }

3. Multi-Level Inheritance:

   • In multi-level inheritance, a subclass inherits from another subclass, creating a chain of inheritance.
   • Each class in the chain inherits properties and behaviors from its immediate parent class.
   • This is a common form of inheritance and helps create a hierarchy of related classes.

   class Animal {
       // ...
   }
   
   class Dog extends Animal {
       // ...
   }
   
   class GermanShepherd extends Dog {
       // ...
   }

4. Hierarchical Inheritance:

   • In hierarchical inheritance, multiple subclasses inherit from a common superclass.
   • Each subclass shares the properties and behaviors of the common superclass.
   • This allows you to create a family of related classes.

   class Animal {
       // ...
   }
   
   class Dog extends Animal {
       // ...
   }
   
   class Cat extends Animal {
       // ...
   }

5. Hybrid Inheritance (Achieved through Interfaces):

   • Hybrid inheritance combines multiple forms of inheritance, including single inheritance, multiple inheritance (through interfaces), and hierarchical inheritance.
   • In Java, you can achieve a concept similar to hybrid inheritance by using interfaces and combining single and hierarchical inheritance with interface implementation.

   interface Swimmer {
       void swim();
   }
   
   class Animal {
       // ...
   }
   
   class Fish extends Animal implements Swimmer {
       @Override
       public void swim() {
           // ...
       }
   }
   
   class Dog extends Animal {
       // ...
   }