Java：Sun发布J2SE 1.4.2，宣布Tiger发布里程碑

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Sun发布J2SE 1.4.2，宣布Tiger发布里程碑

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Sun宣布了J2SE 1.5的发布里程碑，Tiger将于今年年底之前发布一个beta版本。另外，J2SE 1.4.2（代号“Mantis”——蟑螂）已经发布，修补了4000多个bug，增加了对Itanium CPU的完全支持，提供了两种新的Swing观感：Windows XP和GTK，并加入了两种新的高效GC算法。

看到这条消息，我唯一的感想就是：已经发展了10年的Java居然还有超过4000个bug可以修补，实在是~!@#$%^&*……

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A Roadmap for Java 2 Platform, Standard Edition (J2SE) 1.4.2 and 1.5
by Calvin Austin
June 25, 2003

By the end of 2003, Java developers will be able to get their hands on a beta version of Java 2 Platform, Standard Edition 1.5 (J2SE 1.5). This release and the current 1.4 updates, 1.4.1 and 1.4.2, were covered in the J2SE roadmap session at the 2003 JavaOne Conference. If you were unable to attend the session, or want to refresh your memory, here are the key points from the talk.

J2SE 1.4.1 and 1.4.2 Releases

While the 1.4.1 release ("Hopper"), available September 2002, and its follow on update, 1.4.2 ("Mantis"), due in June 2003, have resolved over 4000 bug fixes, the improvements have not stopped there.

Full support of the Itanium CPU is available and Swing users now have support for two new native Look and Feels, Windows XP and GTK on Linux. In addition to a visual refresh, startup time has also been improved, a request that we have heard loud and clear and that will be further improved in J2SE 1.5

Performance on the server side has been enhanced with two new garbage collectors, a concurrent mark and sweep algorithm and a parallel young space collector. The new concurrent collector can be enabled with -XX:+UseConcMarkSweepGC and the parallel collector with -XX:+UseParallelGC.

The challenge of learning and understanding Java command line options to get the best performance is a subject we are tackling in J2SE 1.5.

J2SE 1.5 Release

J2SE 1.5 ("Tiger") is the next major revision to the Java platform and language; it is currently slated to contain 15 component JSRs and other smaller updates. The release is focused along certain key themes, namely Quality, Monitoring and Manageability, Performance and Scalability, Ease of Development and Desktop Client.

Ease of Development

You may have already heard about some of the new Java Language changes that comprise the Ease of Development theme. JSR 201 contains four of these changes; JSR 175 is the core for Metadata support, while JSR 14 specifies Generics.

The Metadata functionality enables declarative programming, which can offload code generation and manipulation to processing tools. Generic types promotes code re-use of routines without manual casting which would otherwise reduce type safety.

The other four changes are a for loop which understand collections and so removes the need for an implicit iterator; enumerated types which provide additional type safety beyond a final static int solution; autoboxing of primitives which is especially needed when using generics, which does not use primitive types; and finally, importing static constants to improve explicit sharing of static data.

There is a lot more than just language changes in Ease of Development. For those developers who miss printf, one will finally be available. Multi-threaded programs will be easier to write with the new concurrency utilities in JSR 166.

Scalability and Performance

The 1.5 release promises improvements in scalability and performance with a new emphasis on startup time and memory footprint to make it easier to deploy applications running at top speed. Performance ergonomics are built in and a more powerful profiling API will be available from JSR 163.

Monitoring and Manageability

M&M is a key feature of Tiger. Those developers who use JMX in Java 2 Platform, Enterprise Edition (J2EE) will be pleased to see this level of functionality in J2SE. The JVM monitoring will allow full health checking of deployed applications, including low memory detection, error fault handlers and even a stack trace API!

Core XML Support

J2SE 1.5 introduces revisions to the core XML platform, including XML 1.1, SAX 2.0 and DOM Level 3. The complementary Web service technologies, JAX-RPC and JAXB, will continue to be available in the Web services pack. A later J2SE release may include these APIs in the J2SE core.

Desktop Client

The final theme covered was Desktop Client. This focus brings a welcome refresh to the default Look and Feel and also improved skins support. In addition to the startup and footprint improvements, desktop developers have a lot to look forward to.

Unicode 3.1 Support

32-bit surrogate character support will be carefully added to the platform so the Java "char" will still remain at 16 bits.

New IO Support

There are updates to support asynchronous IO and to exploit further use of these APIs in the platform where appropriate.

With new J2SE products, 1.4.2 and 1.5, Java developers have an exciting year ahead of them.