Inheritance

Inheritance

1. extending a class

   • creating a new class
     • child class/subclass of parent
       • opportunity to add functionality that does not exist in original
         • change behavior of existing class

2. Extends Keyword

   • all java classes automatically extend the java.lang.Object class
     • Object = superclass
       • parent, by default is a subclass of Object

3. Relationship

   • example: bird, fish, dog are all subclasses of animal

4. Accessibility

   • within subclass, access superclass and protected methods and fields
     • cannot access superclass's private methods from subclass

5. Method Overriding

   • override method to change behavior
     • override by writing new method in subclass
       • don't have to change anything in parent class

6. Calling Superclass's constructors

   • Implicit calling to the parent's constructor that does not exist
     • compile error
       • compiler adds an implicit call to no argument constructor in Parent

7. Calling the superclass's Hidden Members

   • using super to access hidden member

8. Type Casting

   • FInal classes