Java has become a very popular programming language for the kind of modern software people want to write. Java began as a research project inside Sun Microsystems. The results were posted on the web, and Java took off like a Titan rocket. Sun wisely decided to nurture the market by sharing, and licensed the technology across the computer industry. Today, Java compilers and source code are available for free download from many different organizations. Just about the entire computer industry is backing Java enthusiastically with products and support. In this chapter we'll look at the reasons behind Java's popularity, and summarize the key features of the language.

Java works well for web and server-based applications. It has great features like object-oriented programming, easy database access, and well-designed GUI support. The latest release, Java 2 version 5, has performance tweaks to speed up desktop programs. There are libraries for communicating across networks, and for encryption. It has strong security built in. Most programmers pick up Java quickly. Behind all this, Java is more than just the latest, most popular programming language. It is a way of creating applications that are independent of all hardware and all operating systems.

What Java Does for You: Software Portability

What is meant by “applications that are independent of all hardware and operating systems?” It means you can compile a Java program on any system and run the resulting binary executable file on the same or any other system—on a Macintosh, on Windows 98, NT, 2K, XP, on Solaris, Linux, BSD or any of the varieties of Unix, on IBM's mainframe operating systems, on cell phones, Personal Digital Assistants (PDAs), embedded processors, and even on smart cards (credit cards with a microprocessor and memory), as shown in Figure 1-1.

Figure 1-1. Future-proof software: Your Java application runs on every system. No more “requires Windows XP” or “Linux PPC only” , or “compiled for MacOS X version 10.5”; just “built with Java,” and you're done.

You will even be able to run on future operating system releases, like Microsoft's Longhorn. Java will be ported to all future operating systems of significance. It's also a fast way for new hardware to get software applications that will run on it.

Java unlocks software from being coupled to any specific OS and hardware platform. This new flexibility has made Java very popular with users, IT departments, and software vendors. All three benefit enormously from software portability.