Sunday, August 30, 2009

Java History

JDK 1.0

Codename Oak. Initial release

JDK 1.1

Major additions included:

J2SE 1.2

Codename Playground.

J2SE 1.3

Codename Kestrel. The most notable changes were:

J2SE 1.4

Codename Merlin. This was the first release of the Java platform developed under the Java Community Process as JSR 59. Major changes included:

J2SE 5.0

Codename Tiger. (Originally numbered 1.5, which is still used as the internal version number.) Developed under JSR 176, Tiger added a number of significant new language features:

  • Generics: Provides compile-time (static) type safety for collections and eliminates the need for most typecasts (type conversion). (Specified by JSR 14.)
  • Metadata: Also called annotations; allows language constructs such as classes and methods to be tagged with additional data, which can then be processed by metadata-aware utilities. (Specified by JSR 175.)
  • Autoboxing/unboxing: Automatic conversions between primitive types (such as int) and primitive wrapper classes (such as Integer). (Specified by JSR 201.)
  • Enumerations: The enum keyword creates a typesafe, ordered list of values (such as Day.MONDAY, Day.TUESDAY, etc.). Previously this could only be achieved by non-typesafe constant integers or manually constructed classes (typesafe enum pattern). (Specified by JSR 201.)
  • Swing: New skinnable look and feel, called synth.
  • Varargs: The last parameter of a method can now be declared using a type name followed by three dots (e.g. void drawtext(String... lines)). In the calling code any number of parameters of that type can be used and they are then placed in an array to be passed to the method, or alternatively the calling code can pass an array of that type.
  • Enhanced for each loop: The for loop syntax is extended with special syntax for iterating over each member of either an array or any Iterable, such as the standard Collection classes, using a construct of the form:
            void displayWidgets (Iterable<Widget> widgets) {
               for (Widget w: widgets) {
               w.display();
           }

This example iterates over the Iterable object widgets, assigning each of its items in turn to the variable w, and then calling the Widget method display() for each item. (Specified by JSR 201.)

  • Fix the previously broken semantics of the Java Memory Model, which defines how threads interact through memory.
  • Automatic stub generation for RMI objects.
  • static imports
  • 1.5.0_18 (5u18) is the last release of Java to officially support the Microsoft Windows 9x line (Windows 95, Windows 98, Windows ME). Unofficially, Java SE 6 Update 7 (1.6.0.7) is the last version of Java to be shown working on this family of operating systems.
  • The concurrency utilities in package java.util.concurrent.
  • Scanner class for parsing data from various input streams and buffers.

J2SE 5.0 entered its end-of-life on April 8, 2008 and will be unsupported by Sun as of October 30, 2009.

Java SE 6

Codename Mustang. As of this version, Sun replaced the name "J2SE" with Java SE and dropped the ".0" from the version number. Internal numbering for developers remains 1.6.0. This version was developed under JSR 270.

During the development phase, new builds including enhancements and bug fixes were released approximately weekly. Beta versions were released in February and June 2006, leading up to a final release that occurred on December 11, 2006. The current revision is Update 16 which was released in August 2009.

Major changes included in this version:

  • Support for older Win9x versions dropped. Unofficially Java 6 Update 7 is the last release of Java shown to work on these versions of Windows. This is believed to be due to the major changes in Update 10.
  • Scripting Language Support (JSR 223): Generic API for tight integration with scripting languages, and built-in Mozilla Javascript Rhino integration
  • Dramatic performance improvements for the core platform, and Swing.
  • Improved Web Service support through JAX-WS (JSR 224)
  • JDBC 4.0 support (JSR 221).
  • Java Compiler API (JSR 199): an API allowing a Java program to select and invoke a Java Compiler programmatically.
  • Upgrade of JAXB to version 2.0: Including integration of a StAX parser.
  • Support for pluggable annotations (JSR 269)
  • Many GUI improvements, such as integration of SwingWorker in the API, table sorting and filtering, and true Swing double-buffering (eliminating the gray-area effect).

Java SE 6 Update 10

Java SE 6 Update 10 (previously known as Java SE 6 Update N), while it does not change any public API, is meant as a major enhancement in terms of end-user usability. The release version is currently available for download.

Major changes for this update include:

  • Java Deployment Toolkit, a set of JavaScript functions to ease the deployment of applets and Java Web Start applications.
  • Java Kernel, a small installer including only the most commonly used JRE classes. Other packages are downloaded when needed.
  • Enhanced updater.
  • Enhanced versioning and pack200 support: server-side support is no longer required.
  • Java Quick Starter, to improve cold start-up time.
  • Improved performance of Java2D graphics primitives on Windows, using Direct3D and hardware acceleration.
  • A new Swing look and feel called Nimbus and based on synth.
  • Next-Generation Java Plug-In: applets now run in a separate process and support many features of Web Start applications.

Java SE 6 Update 12

This release includes the highly anticipated 64-bit Java Plug-In (for 64-bit browsers only), Windows Server 2008 support, and performance improvements of Java and JavaFX applications

Java SE 6 Update 14

Java SE 6 Update 14 (6u14) was released as of May 28, 2009.

This release includes extensive performance updates to the HotSpot JIT compiler, compressed pointers for 64-bit machines, as well as support for the G1 (Garbage First) low pause garbage collector.

Some developers have noticed an issue introduced in this release which causes debuggers to miss breakpoints seemingly randomly. Sun has a corresponding bug, which is tracking the issue. The workaround applies to the Client and Server VMs. Using the -XX:+UseParallelGC option will prevent the failure. Another workaround is to roll back to update 13.

Java SE 6 Update 16

As of August 11, 2009, Java SE 6 Update 16 is available, fixing the issue which caused debuggers to miss breakpoints introduced in update 14.

Java SE 7

Java 7 (codename Dolphin) is the next version of Java, currently in the planning and development stages. The Dolphin Project began in August 2006 and is tentatively scheduled for release in 2010. New builds including enhancements and bug fixes are released approximately weekly.

New features that may be integrated in Java 7 include:

  • JVM support for dynamic languages, following the prototyping work currently done on the Multi Language Virtual Machine,
  • A new library for parallel computing on Multi-core processors,
  • Superpackages (JSR 294), which are a way to define explicitly in a library or module which classes will be visible from outside of the library,
  • Swing Application Framework, an infrastructure common to most desktop applications, making Swing applications easier to create.
  • Replacing the existing concurrent low-pause garbage collector (also called CMS or Concurrent Mark-Sweep collector) with the G1 garbage collector.
  • Various small language changes, grouped in a project called Project Coin. These changes are still evaluated but could include: Strings in switch, more concise calls to constructors with type parameters, or multi-catch in exceptions.
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