Three years ago, I wrote an article for JavaWorld called "Java Scripting Languages: Which Is Right for You?" When I collected the interpreters to compare, I tried to choose ones that seemed a good fit for a demanding commercial application. Ideally, I wanted an interpreter that would ease the extension of the application's user interface, have readable scripting code, be reliable, fast, well-supported, well-documented, and complete. At that time, I narrowed the list down to Jacl, Jython, Rhino, and BeanShell.... more »

Some Java applications' requirements make integration with a scripting language necessary. For example, your users may need to write scripts that drive the application, extend it, or contain loops and other flow-control constructs. In such cases, it's sensible to support a scripting language interpreter that can read user scripts, then run them against your Java application's classes. To accomplish that task, run a Java-based scripting language interpreter in the same JVM as your application.... more »

Properties files are used to store and maintain the localized strings at the heart of most internationalized Java applications. It's too bad maintaining several properties files can be such a headache. In this article Melih Çetin introduces the Properties Pre-Processor, an XML-based utility that enables UTF-8 encoding and lets you maintain localized strings for all of your supported locales in a single XML file, as well as easily sharing them across multiple applications.... more »

Editor's Note: With this installment, we kick off a new column, "The Open Road," by Java in a Nutshell author David Flanagan. Our mission for this column is to provide visibility into the open source development of the next version of Java, which is happening here on java.net. In this article, David looks at the state of the OpenJDK and JDK 7 projects, proposed language changes that may appear in Java 7, and prominent APIs that are being developed for possible inclusion in Java 7. Each future installment will provide an update on what's currently happening in the latest builds from the project, along with a deep dive into a new feature or API that's tracking for inclusion in Java 7 (David discusses some of these in this first installment). We hope you'll enjoy this early exposure to the next version of Java, and that you'll be encouraged to download, build, and/or run the various Java 7-related projects hosted on java.net.... more »

Sun developer Danny Coward says "Compatibility is king", but Sun is not standing still in the Java space. At last week’s JavaOne conference he unveiled some projects that R&D is working on for the upcoming "Dolphin" release of Java, due out in 2008. The proposed changes are in three areas: languages, packaging, and ease of development.... more »

In short, don't rely on the finalize() method as your only cleanup method, especially if it is deleting files. Instead make up a cleanup method (cleanup() works nicely) that lazy deletes things. Here is an example.... more »

As promised, one of the things I'd like to focus on in this blog is the detection of singletons and other global state. In fact, I've been working on a tool to do just that during my summer internship at Google, and I've just gotten permission to open source it. The tool, called Google Singleton Detector, is a Java application that analyzes the Java bytecode of an existing code base to detect the presence of singletons and other global state. It produces a nice graph which shows singletons and all of the classes which use them.... more »

The metadata facility allows classes, interfaces, fields, and methods to be marked as having particular attributes, enabling them to be processed in special ways by development tools, deployment tools, or run-time libraries.... more »

You've nailed down the functional characteristics of scripting languages and seen how Python compares to Java for banging out fast code. Now look at the big picture: how does a non-native scripting language interact with the JVM and how will the strengths and weaknesses of scripting affect the runtime performance, robustness, and maintainability of your Java applications. Find out what else you need to know about scripting in this second half of the JavaWorld excerpt from Dejan Bosanac's Scripting in Java: Languages, Frameworks, and Patterns (Addison-Wesley Professional, August 2007).... more »

One of the major changes introduced late in the process of releasing Groovy 1.0 was the addition of the Meta-Object-Protocol or MOP. (Well, late is relative, considering it took 2-3 years to release Groovy 1.0... more »