Java Programming: Advanced Topics1 Introduction to Advanced Java Programming Chapter 1

Java Programming: Advanced Topics 1

Introduction to Advanced Java Programming

Chapter 1


Objectives

• Review what Java is and differences between the three editions of the Java 2 platform: J2SE, J2EE, and J2ME

• Explore the context in which Java and related technologies are evolving

• See how Java supports object-oriented programming and look at some popular design patterns


Objectives (Cont.)

• Learn how to use the basic tools that version of Java 2 Software Development Kit provides, especially javac, java, javadoc, and jar


Overview of the Java Platform

• The Java language is object-oriented• Java code is architecture-neutral and portable• Java is network-savvy• Java programs are secure• Java is high performance


Java Programs and Components • JavaBeans: classes or program components

that conform to strict programming conventions• Applets: components that can be launched from

HTML documents and run in a Web browser or applet viewer utility

• Servlets: components that generate content for Web pages at runtime

• Enterprise JavaBeans (EJBs): server-side components used in distributed enterprise environments


The Three Editions of the Java 2 Platform

• The Java 2 platform comes in three versions:– Java 2 Standard Edition (J2SE)– Java 2 Enterprise Edition (J2EE)– Java 2 Micro Edition (J2ME)


Containers in the n-Tier J2EE Architecture


A Brief History of the Java Platform

• 1995: Version 1.0 (Sun Microsystems)• 1997: Version 1.1• 1998: Java 2 platform• 1999: J2SE, J2EE, and J2ME• 2001: Version 1.3 of J2SE• 2002: Version 1.4• 2002: Version 1.3 of J2EE


Object-Oriented Programming in Java

• The key benefits of object-oriented programming are:– code reuse– flexibility to respond to changing circumstances and

requirements– ease of maintenance


Object-Oriented Programming in Java (Cont.)

• A program is a collection of objects that send messages to each other

• Object-oriented analysis and design (OOAD): – First stage: perform object-oriented problem analysis– Second stage:

• Identify classes to be implemented• Identify fields and methods the classes must contain to

model the behavior of real-life objects


Object-Oriented Methodology

• Java lends itself to iterative and incremental object-oriented development methodology

• In large projects, functionality is typically added in stages and each identifiable stage is an increment

• An iteration is a short-term development cycle within an increment


Object-Oriented Features of Java

• Java supports the following fundamental features of all object-oriented languages:– Abstract data types– Encapsulation– Inheritance– Polymorphism


Design Patterns and Frameworks

• Design pattern: proposed solution to common design problem

• Frameworks: collections of reusable classes• Popular design patterns:

– Model-View-Controller design pattern – Singleton design pattern – Factory design pattern– Adapter design pattern– Façade design pattern


Model-View-Controller Design Pattern


An Implementation of the Singleton Design Pattern


An Implementation of the Factory Design Pattern


Standard SDK Tools

• The Java platform includes a tool set for developing Java programs

• The J2SDK tools run only in a command-line window and provide basic functionality


Standard SDK Tools(Cont.)

• Standard J2SDK tools:– javac compiler– java launcher– javadoc documentation builder– jar packaging utility


How the Launcher Finds Classes

• Java command locates bytecode files by class name

• Launcher loads bytecode from the file with the extension .class and with the case-sensitive base filename that matches the class name


How the Compiler Finds Classes

• For public classes– Source file must have the same name as the

class– Every public class must be in a separate file

• javac command has a -sourcepath option to specify the location of input source files when different from the location of compiled classes


javadoc Comments

• The javadoc tool is a utility for generating HTML documentation directly from comments in Java source code

• Doc comments – Start with a slash and two asterisks (/**)– Terminate with one asterisk and a slash (*/)


javadoc Comments(Cont.)

• Doc comments can appear before the following kinds of declarations:– Class– Interface– Field– Method


javadoc Comments(Cont.)


Creating HTML from javadoc

• To get HTML output in the standard format, run the javadoc program

• Doclet: plug-in program for javadoc that formats and outputs required documentation

• The javadoc tool – Preprocesses doc comments into a data structure– Delegates to a doclet conversion of data into output


An index.html File Generated by javadoc


Packaging Programs for Distribution

• The standard way to distribute J2SE is to combine files into a Java archive file using the jar tool

• Before running the jar tool, make sure your files are in the proper folders


Summary• The Java 2 platform comes in three

versions: Java 2 Standard Edition (J2SE), Java 2 Enterprise Edition (J2EE), and Java2 Micro Edition (J2ME).

• You can write different kinds of programs in Java including standalone applications, applets, servlets and JSPs, JavaBeans and Enterprise JavaBeans (EJBs).


Summary (Cont.)• Java is an object-oriented language and lends

itself to the creation of reusable components.• Java language supports abstract data types,

encapsulation, inheritance, and polymorphism, uses iterative and incremental methodology, and implements design patterns.

• The SDK includes command line tools: the javac compiler, java launcher, javadoc documentation builder, and jar packaging utility.

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Java Programming: Advanced Topics1 Introduction to Advanced Java Programming Chapter 1