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Java for poets

February 1998

Java. Is there anything to the most hyped technology in recent memory? Or is it just another in a long line of buzzwords seemingly designed to part a fool client from from her money? Well, it's taken me a long time to decide, and I think there's something worth knowing about Java. I'll tell you what I've learned, where I'm going, and how you can come along.

Recently I went to "Sun" Microsystem's "JavaOne '98" show in the George Moscone Convention Center in downtown San Francisco. Stunned at first by the incongruity of seeing computer folks grouped by the programming language they use, I recovered enough to look past the swarm of programming tools and how-to books and see folks who were excited by something. To tell the story let's start at the beginning, where programmers tear out their hair.

For those of us who write software the challenge isn't the programming, it's programming in such a way that the number of changes required to deliver the software on various platforms - Macintosh, Windows, UNIX - is minimized. If the software leverages knowledge about the platform on which it's running (perhaps to deliver faster graphics) it can become a major undertaking to "port" the software from one platform to another. That's why there's frequently a long lag time between ports of game software - which commonly take advantage of every little trick to eke performance from a platform. For DOOM the delay was several years.

It would be a very good thing if I could write software for one platform and have it run on other platforms. C and C++ can be programmed with portability in mind, and you have to try to program non-portably in Perl, but nothing promises the ability to "write once, run anywhere" with the same force as does Java. It would be an even better thing if the available platforms ranged from the tiny (cellular telephones and "palmtop" handheld computers) to the huge (mainframes and supercomputers). Java promises to scale in just such a manner. (In fact, this week Sony licensed Java from Sun for use in a line of cellular telephones.)

The Software You'll Need

In order to write Java on Macintosh you'll need these free software packages:

1. The MacOS Runtime for Java (MRJ) is the implementation of Java for Macintosh. Check the Apple DevWorld Java page for the latest versions. As of this writing the current version is 2.0.

2. The MRJ Software Development Kit (SDK) includes tools needed to convert Java code into running software. As of this writing the current released version is 2.0, but an early access release of 2.0.1ea2 is available. I used the latter in the writing of my Java (and this article).

The installation process is straight-forward and requires no comment.

The Books You'll Read

As a result of attending JavaOne I obtained a variety of books and CD-ROMs about Java. I've been reading them for the majority of each day since the show. Here are my nutshell reviews:

Vital Hints

Starting to write Java is a big undertaking. Without these hints you'll be spinning your wheels.

Alternatives to setting the ClassPath

Java requires that you put each class into its own file. The ClassPath tells the Java compiler where to find these classes. Setting the ClassPath is a royal pain. You'll be creating a folder for each Java program you write (it's where you store each of the class definitions). Put an alias to these folders in the .../ System Folder/ Extensions / MRJ Libraries / MRJClasses folder and the ClassPath will automatically be set.

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