Implementing Classes

Implementing Classes

1. Superclass(parent) versus subclass(child)

   • Extending to a class
     • Gives the subclass the ability to use the methods used before, or even add more.
       • Abstract Classes
         • A class that has one or more abstract methods.
       • Interfaces
         • A class made entirely of abstract methods. Must be implemented instead of extended. Famous interface is the Arraylist interface
       • Abstract Methods: Methods with no body; must be given an implementation by the subclass.
     • Implementing Superclass
       • Overriding an inherited method means providing a method in a child class with the same method signature (method name and parameter type list) and return type as a method in the parent class.
       • Overloading a method is when several methods have the same name but the parameter types, order, or number are different. Allows for multiple constructors in the same class.

2. Variables

   • Instance variables
     • Private variables for only the class. Accessor methods can be written to give the programmer the variable using encapsulation
   • Parameters
     • Variables given to the method.
       • Implicit: The object used to get to the method. For example, student.setAge(15);. The implicit parameter is the student object
       • Explicit: the value(s) the method will be taking in and using to run. For example, student.setAge(15);. "15" would be the explicit parameter.

3. Encapsulation

   • Hides the instance variables by making them private. Generally, accessor methods will be public to allow the access of these private variables.