It teaches you the
core concepts behind object-oriented programming: objects, messages, classes,
and inheritance. This lesson ends by showing you how these concepts translate
into code. Feel free to skip this lesson if you are already familiar with
object-oriented programming.
Lesson: Object-Oriented Programming Concepts
If
you've never used an object-oriented programming language before, you'll need
to learn a few basic concepts before you can begin writing any code. This
lesson will introduce you to objects, classes, inheritance, interfaces, and
packages. Each discussion focuses on how these concepts relate to the real
world, while simultaneously providing an introduction to the syntax of the Java
programming language.
An
object is a software bundle of related state and behavior. Software objects are
often used to model the real-world objects that you find in everyday life. This
lesson explains how state and behavior are represented within an object,
introduces the concept of data encapsulation, and explains the benefits of
designing your software in this manner.
A
class is a blueprint or prototype from which objects are created. This section
defines a class that models the state and behavior of a real-world object. It
intentionally focuses on the basics, showing how even a simple class can
cleanly model state and behavior.
Inheritance
provides a powerful and natural mechanism for organizing and structuring your
software. This section explains how classes inherit state and behavior from
their superclasses, and explains how to derive one class from another using the
simple syntax provided by the Java programming language.
An
interface is a contract between a class and the outside world. When a class
implements an interface, it promises to provide the behavior published by that
interface. This section defines a simple interface and explains the necessary
changes for any class that implements it.
A
package is a namespace for organizing classes and interfaces in a logical
manner. Placing your code into packages makes large software projects easier to
manage. This section explains why this is useful, and introduces you to the
Application Programming Interface (API) provided by the Java platform.
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