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Language improvements and models make great Java

Java enhancements, like generics and asserts, improve this already cool programming language

By Eric Armstrong, JavaWorld.com, 06/08/01

June 8, 2001-- As an object-oriented, network-enabled, platform-spanning language smart enough to include primitive data types for efficiency, Java has always been cool. But it just keeps getting better!

Once you code in a few different languages, you come to realize just how important the language is to solving a given problem. When you're using the right language, some puzzles just fall apart. But as someone who once tutored freshman who were ill-fated enough to take a class that forced them to solve real-world business problems using FORTRAN, I can tell you that the wrong language can turn a molehill of a problem into a nearly insurmountable mountain.

And, for all its beauty, Java experienced a few problems of its own. One of the major gaffes was the inconsistent, persnickety mechanisms for looping over arrays, vectors, and strings. Sun Microsystems Senior Staff Engineer Joshua Bloch came to the rescue on that front with the elegant Collections API. Just as Java itself is platform-spanning, Collections present a mechanism-spanning API, thereby creating uniform, consistent mechanisms for writing code.

The latest language improvements include generics and assertions. In addition, a variety of application templates and design patterns have become available to help you write better code more quickly. This article explores these enhancements:

• Generics
• Assertions
• Effective Java
• J2EE Blueprints
• Common interface standards

Generics

Gilad Bracha, the specification lead and computational theologist for Sun, announced that the generics facility will arrive in the Tiger release of the Java platform (version 1.5). The bad news is that 1.5 is not due to be available until 2003. The good news is that an early-access version is available now, and you can actually make use of the technology in some practical ways.

It turns out that Merlin's (JDK 1.4) compiler is the generic-capable compiler, only with generics disabled. That means that the generic facility will undoubtedly be stable by the time it arrives. But it also means we'll have to wait a fairly long time for something that is (almost) here today.

(Note: For those familiar with the generics landscape, Bracha mentioned that Java's generics facility is based on Pizza and Generic Java, and that much of the documentation on those precursors (available on the Web) applies to generics.)

The advantages of generics

The ability to write generic classes, methods, and interfaces makes it possible to write general template classes. However, they significantly differ from C++ templates, as you'll see. Such template classes can be reused for multiple purposes without requiring general Object parameters that must be cast to the appropriate data type when the class is used.

For example, writing a generic data pool would make it possible to cache and deliver objects of type "X" to an application. One application could then create a pool of Car objects, while another application could create a pool of network Connectionobjects. Both applications would use the generic data pool facility. Neither application would have to write a data pool library, but both would be able to access Carobjects or Connection objects, as appropriate, as though they had written a custom library.

 

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