Java Programming, 2EIntroductory Concepts

and Techniques

Chapter 1An Introduction to

Java and Program Design

2Chapter 1: An Introduction to Java and Program Design

Object-Oriented Programming

• Data and the operations on the data are packaged into a unit

• An interface of properties and functions is exposed to the outside world

3Chapter 1: An Introduction to Java and Program Design

Classes

• Specifications of data and operationsClass rectangle

{

int length;

int width;

int size();

int perimeter();

}

4Chapter 1: An Introduction to Java and Program Design

Objects

• An object is an instance of a class• A real entity that exists in the system

– Take up a block of memory

• Many objects of the same class can exist at the same timeTwo rectangle objects: rect1, rect2rect1.length != rect2.lengthrect1.width != rect2.widthrect1.size() != rect2.size()

5Chapter 1: An Introduction to Java and Program Design

Java

• Designed and developed by Sun Microsystems in the early 1990’s

• One of the most widely used object-oriented programming languages

6Chapter 1: An Introduction to Java and Program Design

Characteristics of Java

• Portable– Platform-independent– “write once, use everywhere”

• Secure– Protection against misuse of code

• Robust– Strongly typed and incorruptible data

7Chapter 1: An Introduction to Java and Program Design

Java Program Types

• Console and Windowed applications

• Applets

• Servlets

• Web Services

• JavaBeans

8Chapter 1: An Introduction to Java and Program Design

Console Applications

• Stand-alone programs using a command-line interface

9Chapter 1: An Introduction to Java and Program Design

Windowed Applications

• Stand-alone programs using a graphical user interface (GUI)

10Chapter 1: An Introduction to Java and Program Design

Applets

• Client-side programs executed within a Web browser

11Chapter 1: An Introduction to Java and Program Design

Servlets

• Server-side programs hosted and run on a Web server

• Used in conjunction with Java Server Pages (JSP) to provide sophisticated server-side logic

• Enable connections to databases through Java Database Connectivity (JDBC)

12Chapter 1: An Introduction to Java and Program Design

Servlets

13Chapter 1: An Introduction to Java and Program Design

Web Services

• Services receive information requests over the Web and return the requested data

14Chapter 1: An Introduction to Java and Program Design

JavaBeans• Reusable software components

15Chapter 1: An Introduction to Java and Program Design

Java Program Development Using J2SE• The Java Compiler

– Converts code into bytecode

• The Java Virtual Machine – Contains an interpreter to execute the bytecode

• The Java API– The standard set of packages available in Java

• The Java Applet Viewer– Mini browser to display Java applets

16Chapter 1: An Introduction to Java and Program Design

Java Program Development Using J2SE• The Java Compiler

– Converts code into bytecode

• The Java Virtual Machine – Contains an interpreter to execute the bytecode

• The Java API– The standard set of packages available in Java

• The Java Applet Viewer– Mini browser to display Java applets

• Enter Java source code using any text-editor

17Chapter 1: An Introduction to Java and Program Design

Summary

• Classes & Objects

• Characteristics of Java

• Java program types

• Java program development

18Chapter 1: An Introduction to Java and Program Design

For Your Interests

• Java Technology: The Early Years