News

JDK 7 Developer Preview Now Available

• By John K. Waters
• February 23, 2011

The Developer Preview of the Java SE Development Kit version 7 (JDK 7) is now available for download, Oracle announced Wednesday.

Build b130 (a.k.a. Milestone 12) is intended for broad testing by developers, deployers and end users, Oracle's Mark Reinhold wrote in his blog post announcing the release. Reinhold is principle engineer for Java SE and the OpenJDK.

"We've run all tests on all supported platforms and haven't found any glaring issues," Reinhold said. "We've also fixed 456 bugs since reaching the Feature-Complete milestone back in January."

Reinhold essentially warned against taking that Milestone 11 release for a test drive when it was announced last month, advising developers to wait for Milestone 12. " We expect the most glaring issues to be fixed in M12, so we'll strongly encourage developers, deployers and end users to download and test that build," Reinhold said.

Released through the OpenJDK project, JDK 7 emphasizes four improvement areas: modularization, multi-language support, developer productivity and performance.

The focus on modularity is a large-scale effort to refactor the Java SE platform in to smaller, interdependent modules. Among other advantages, modularization will reduce the size of the platform download. A smaller footprint could up performance of desktop apps, Oracle said, and the modules fit better into devices with restricted memory.

Enhancements in this version are meant to improve compatibility among Java and some popular dynamic languages, such as Ruby and Python, through better-than-native implementations of these languages on top of the Java Runtime Environment (JRE).

Developer productivity gets a bump through Project Coin (JSR 334), which is a set of small language changes designed to simplify common, day-to-day programming tasks; concurrency and collections updates (JSR 166 package jsr166y); annotations on Java types (JSR 308), an extension to the Java annotation syntax that permits annotations on any occurrence of a type; and new I/O APIs for the Java platform (JSR 203), including APIs for filesystem access, scalable asynchronous I/O operations, socket-channel binding and configuration, and multicast datagrams.

"If you've been watching JDK 7 development from the sidelines," Reinhold said in his announcement, "then now is a great time to download a build and take it for a spin. See if your favorite project still compiles and runs; see if it runs any faster than before; or try out one of the many new features."

The JDK 7 Developer Preview is available for download now from the java.net Web site. Downloaders must accept the Pre-Release Software Evaluation Agreement, which grants a limited license to view the source code portions of the Licensed Software internally for the purposes of evaluation only.