OOP 2, Classes and Objects

III. Inheritance Revisited

Abstract Classes

Abstract Class Example

Abstract Class Subclasses

Using the Abstract Class

Abstract Classes: Miscellaneous

Final Classes

Summary: Class Modifers

Interfaces

Interfaces

A System Example

A User Example

Using an Interface

Extending an Interface

Interfaces and Name Conflicts

Interfaces and Forwarding.

Interfaces and Callback

A Timer Class with Caller

Interfaces and Abstract Classes

II. Encapsulation Revisited

Packages

Java API (1.1)

Some Core API Packages

The Package java.lang

User Packages

Name Conflict Problems

How the Compiler Works

A Java Compilation Unit

Automatic Compilation

Relating Package Names to Dirs.

CLASSPATH-Package-Class

How the Compiler Searches

A Common Error

Avoiding Clashes on the Internet

Data Hiding in Java

Class Visibility

Class Visibility Example

Variable Visibility

Private Variables

A Java Class with Total Visibility

The Java Class with Hidden Data

Changing the Data Representation

Java Access Modifiers

Access Table

Public - Visible Everywhere

Protected - Visible in Package + any subclasses

Default - Visible in Package Only

Private Protected - Visible in Subclasses Everywhere

Private - Visible only in class

Hiding Methods

Interesting Private Example

Interesting Protected Example

Other Data Field Modifiers

Other Method Field Modifers