Inheritance

Inheritance

1. Overview

   • An important feature in OOP used to extend a class.
     • Use the "extends" keyword after class name and before parent
       • Example: public class Child extends Parent{}
         • Multiple inheritance is allowed in C++ unlike JAVA.
   • Parent-Child Relationship between classes.
     • The child class can be extendable until you declare it as "final"
       • Use "final" keyword to prevent classes from being subclassed or extended.
   • Allows you to change behaviors of an existing class to better suit your needs.

2. "Is-A Relationship"

   • A special relationship between the superclass and the subclass.
     • Superclass being a big class and the subclasses are the different types of the superclass.
     • Must not assign an instance of a subclass to a reference variable of the parent type.
     • A subclass inherits all public methods and fields from the superclass.

3. Accessibilty

   • Have access to superclass's public methods and fields.

4. Method-Overiding

   • By extending a class, you change the method's behavior within the parent class.
   • Write in the subclass a method that has the same signature as it does in the parent class.
   • Method-Overloading
     • Only the name is the same, and the list of argument isn't.
   • You can not override a final method

5. Type Casting

   • Cast an object to another type
     • Only can cast an instance of a subclass to its parent.
   • Casting an object to a parent class is called upcasting.