Java Studio Creator Field Guide 2nd Ed 2004.pdf

J AVA TM S TUDIO

F IELD G UIDE

S ECOND E DITION

J AVA T ECHNOLOGY

O VERVIEW

Topics in This Chapter

• The Java Programming Language

• JavaBeans Components

• NetBeans Software

• The XML Language

• The J2EE Architecture

• JavaServer Faces Technology

• JDBC and Databases

• Ant Build Tool

• Web Services

• EJBs and Portlets

Chapter

elcome to Creator! Creator is an IDE (Integrated Development

Environment) that helps you build web applications. While many

IDEs out in the world do that, Creator is unique in that it is built on

a layered technology anchored in Java. At the core of this technol-

ogy is the Java programming language. Java includes a compiler that produces

portable bytecode and a Java Virtual Machine (JVM) that runs this byte code on

any processor. Java is an important part of Creator because it makes your web

applications portable.

But Java is more than just a programming language. It is also a technology

platform . Many large systems have been developed that use Java as their core.

These systems are highly scalable and provide services and structure that

address some of the high-volume, distributed computing environments of

today.

1.1 Introduction

Creator depends on multiple technologies, so it’s worthwhile touching on them

in this chapter. If you’re new to Java, many of its parts and acronyms can be

daunting. Java technologies are divided into related packages containing

classes and interfaces. To build an application, you might need parts of one sys-

tem and parts of another. This chapter provides you with a road map of Java

Chapter 1 Java Technology Overview

technologies and documentation sources to help you design your web applica-

tions with Creator.

We’ll begin with an overview of the Java programming language. This will

help you get comfortable writing Java code to customize your Creator applica-

tions. But before we do that, we show you how to find the documentation for

Java classes and methods. This will help you use them with confidence in your

programs.

Most of the documentation for a Java Application Program Interface (API)

can be accessed through Creator’s Help System, located under Help in the

main menu. Sometimes all you need is the name of the package or the system

to find out what API a class, interface, or method belongs to. Java consists of

the basic language (all packages under java ) and Java extensions (all packages

under javax ). Once you locate a package, you can explore the interfaces and

classes and learn about the methods they implement.

You can also access the Java documentation online. Here’s a good starting

point for the Java API documentation.

http://java.sun.com/docs/

This page contains links to the Java 2 Platform Standard Edition, which con-

tains the core APIs. It also has a link to all of the other Java APIs and technolo-

gies, found at

http://java.sun.com/reference/docs/index.html

Creator is also built on the technology of JavaServer Faces (JSF). You can

find the current JSF API documentation at

http://java.sun.com/j2ee/javaserverfaces/1.0/docs/api/

index.html

JSF is described as part of the J2EE Tutorial, which can be found at

http://java.sun.com/j2ee/1.4/docs/tutorial/doc/index.html

These are all important references for you. We’ve included them at the

beginning of this book so it’s easy to find them later (when you’re deep in the

challenges of web application development). For now, let’s begin with Java as a

programming language. Then we’ll look at some of the other supporting tech-

nologies on which Creator is built.

1.2 The Java Programming Language

This cursory overview of the Java programming language is for readers who

come from a non-Java programming environment. It’s not meant to be an in-

depth reference, but a starting point. Much of Creator involves manipulating

components through the design canvas and the components’ property sheets.

However, there are times when you must add code to a Java page bean (the

supporting Java code for your web application’s page) or use a JavaBeans com-

ponent in your application. You’ll want a basic understanding of Java to more

easily use Creator.

Object-Oriented Programming

Languages like C and Basic are procedure-oriented languages, which means

data and functions are separated. To write programs, you either pass data as

arguments to functions or make your data global to functions. This arrange-

ment can be problematic when you need to hide data like passwords, customer

identification codes, and network addresses. Procedure-oriented designs work

fine when you write simple programs but are often not suitable to more com-

plex tasks like distributed programming and web applications. Function librar-

ies help, but error handling can be difficult and global variables may introduce

side effects during program maintenance.

Object-oriented programming, on the other hand, combines data and func-

tions into units called objects . Languages like Java hide private data ( fields ) from

user programs and expose only functions ( methods ) as a public interface. This

concept of encapsulation allows you to control how callers access your objects. It

allows you to break up applications into groups of objects that behave in a sim-

ilar way, a concept called abstraction . In Java, you implement an object with a

Java class and your object’s public interface becomes its outside view . Java has

inheritance to create new data types as extensions of existing types. Java also

has interfaces, which allow objects to implement required behaviors of certain

classes of objects. All of these concepts help separate an object’s implementa-

tion (inside view) from its interface (outside view).

All objects created from the same class have the same data type. Java is a

strongly typed language, and all objects are implicitly derived from type

Object (except the built-in primitive types of int , boolean , char , double ,

long , etc.). You can convert an object from one type to another with a converter.

Casting to a different type is only allowed if the conversion is known by the

compiler. Creator’s Java editor helps you create well-formed statements with

dynamic syntax analysis and code completion choices. You’ll see how this

works in Chapter 2.

Error handling has always been a tough problem to solve, but with web

applications error handling is even more difficult. Processing errors can occur

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