Mark Robinson

"Variables have types, objects have classes." This phrase, borrowed from the Java Language Specification, succinctly answers several questions that, judging by the frequency of their appearance in the Java news groups, are a common source of confusion for many Java programmers. It reinforces that variables and objects are different things and helps explain why "casts" are necessary, why Java "constants" can appear to be modifiable and what it really means for an argument to be passed to a method "by value". This month, I'll begin with some background information that will help those who are not yet comfortable with the terms types, variables, objects, classes and references to get up to speed. Then, I'll present a problem, based upon the exam questions for Sun's Java Certification Program, that will test your understanding of references and objects. Variables are pl... (more)

Variables Have Types, Objects Have Classes

Last month, I introduced the terms types, variables, classes, objects and references. If you understood the examples and correctly answered the test question I provided at the end of the article, you're well on your way to mastering the essential concepts that govern how all Java programs work. If you missed the article, look for it on SYS-CON's Web site at http://www.JavaDevelopersJournal.com. This month, I'm going to concentrate on eight tenets of Java programming. These tenets are the "truths" that will guide you safely through the darkest complexities of Java syntax as it r... (more)

Is Java For You?

Welcome to Java Foundations! Java is purported, by its designers, to be a "simple" programming language. While reasonable arguments can be made that illustrate Java's simplicity in comparison to a language like C++, developers coming from languages such as the xBASE derivatives, Visual Basic or PowerBuilder, will probably not agree that Java is simple at all. To fully exploit the power of Java, you need to understand and apply the principles of object-oriented analysis, design and programming. You need to learn the nearly 150 classes that comprise the core Java class libraries. Y... (more)

Open Source Takes the Mystery Out of Mobile E-mail

This session will be specifically tailored for developers and IT managers working on mobile e-mail and other mobile applications. While proprietary mobile e-mail companies protect their code and profits, the mobile open source approach boasts a transparent community of developers contributing to the code. This session will equip developers with the information they need to build mobile e-mail and applications that support mobile services regardless of network type or device manufacturer.  A complete overview of the Sync4j open source mobile application server will be included. Fu... (more)