Java version history

The Java language has undergone several changes since JDK 1.0 as well as numerous additions of classes and packages to the standard library. Since J2SE 1.4, the evolution of the Java language has been governed by the Java Community Process (JCP), which uses Java Specification Requests (JSRs) to propose and specify additions and changes to the Java platform. The language is specified by the Java Language Specification (JLS); changes to the JLS are managed under JSR 901.

In addition to the language changes, much more dramatic changes have been made to the Java Class Library over the years, which has grown from a few hundred classes in JDK 1.0 to over three thousand in J2SE 5. Entire new APIs, such as Swing and Java2D, have been introduced, and many of the original JDK 1.0 classes and methods have been deprecated. Some programs allow conversion of Java programs from one version of the Java platform to an older one (for example Java 5.0 backported to 1.4) (see Java backporting tools).

After the Java 7 release, Oracle promised to go back to a 2-year release cycle.^[1] However, in 2013, Oracle announced that they would delay Java 8 by one year, in order to fix bugs related to Java security.^[2]

Java 8 is the only publicly supported version, while after public support periods of older versions has ended, non-public updates have been issued for Java 7 and earlier.

JDK Alpha and Beta

The first alpha and beta Java public releases in 1995 had highly unstable APIs and ABIs. The supplied Java web browser was named WebRunner.

JDK 1.0

The first version was released on January 23, 1996 and called Oak.^[3][4] The first stable version, JDK 1.0.2, is called Java 1.^[4]

JDK 1.1

Major additions in the release on February 19, 1997 included:^[5]

• an extensive retooling of the AWT event model
• inner classes added to the language
• JavaBeans
• JDBC
• RMI
• reflection which supported Introspection only, no modification at runtime was possible.
• JIT (Just In Time) compiler on Microsoft Windows platforms, produced for JavaSoft by Symantec
• Internationalization and Unicode support originating from Taligent^[6]

J2SE 1.2

Codename Playground. The release on December 8, 1998 and subsequent releases through J2SE 5.0 were rebranded retrospectively Java 2 and the version name "J2SE" (Java 2 Platform, Standard Edition) replaced JDK to distinguish the base platform from J2EE (Java 2 Platform, Enterprise Edition) and J2ME (Java 2 Platform, Micro Edition). This was a very significant release of Java as it tripled the size of the Java platform to 1520 classes in 59 packages. Major additions included:^[7]

• strictfp keyword
• the Swing graphical API was integrated into the core classes
• Sun's JVM was equipped with a JIT compiler for the first time
• Java plug-in
• Java IDL, an IDL implementation for CORBA interoperability
• Collections framework

J2SE 1.3

Codename Kestrel. The most notable changes in the May 8th, 2000 release were:^[8][9]

• HotSpot JVM included (the HotSpot JVM was first released in April 1999 for the J2SE 1.2 JVM)
• RMI was modified to support optional compatibility with CORBA
• Java Naming and Directory Interface (JNDI) included in core libraries (previously available as an extension)
• Java Platform Debugger Architecture (JPDA)
• JavaSound
• Synthetic proxy classes

J2SE 1.4

Codename Merlin. The February 6th, 2002 release was the first release of the Java platform developed under the Java Community Process as JSR 59. Major changes included:^[10][11]

• Language changes
  • assert keyword (specified in JSR 41)
• Library improvements
  • Regular expressions modeled after Perl regular expressions
  • Exception chaining allows an exception to encapsulate original lower-level exception
  • Internet Protocol version 6 (IPv6) support
  • Non-blocking IO (named New Input/Output, NIO) (specified in JSR 51)
  • Logging API (specified in JSR 47)
  • Image I/O API for reading and writing images in formats like JPEG and PNG
  • Integrated XML parser and XSLT processor (JAXP) (specified in JSR 5 and JSR 63)
  • Integrated security and cryptography extensions (JCE, JSSE, JAAS)
  • Java Web Start included (Java Web Start was first released in March 2001 for J2SE 1.3) (specified in JSR 56)
  • Preferences API (java.util.prefs)

Public support and security updates for Java 1.4 ended in October 2008. Paid security updates for Oracle customers ended in February 2013.^[12]

J2SE 5.0

Codename Tiger. The release on September 30, 2004 was originally numbered 1.5, which is still used as the internal version number. The number was changed to "better reflect the level of maturity, stability, scalability and security of the J2SE".^[13] This version was developed under JSR 176.

J2SE 5.0 entered its end-of-public-updates period on April 8, 2008; updates are no longer available to the public as of November 3, 2009. Updates were available to paid Oracle customers until May 2015.^[14]

Tiger added a number of significant new language features:^[15][16]

• 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)
• 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 (specified by JSR 201)
• Improved semantics of execution for multi-threaded Java programs; the new Java memory model addresses issues of complexity, effectiveness, and performance of previous specifications^[17]
• Static imports

There were also the following improvements to the standard libraries:

• Automatic stub generation for RMI objects
• Swing: New skinnable look and feel, called synth
• The concurrency utilities in package java.util.concurrent^[18]
• Scanner class for parsing data from various input streams and buffers

Java 5 is the last release of Java to officially support the Microsoft Windows 9x line (Windows 95, Windows 98, Windows ME),^[19] while Windows Vista is the newest version of Windows that J2SE 5 was supported on prior to Java 5 going end of life in October 2009.^[12]

Java 5 Update 5 (1.5.0_05) is the last release of Java to work without any problems on Windows NT 4.0.^[20]

Java 5 is the default version of Java installed on Apple Mac OS X 10.5 (Leopard). Java 6 can be installed and set as the default to be used on 64-bit (Core 2 Duo and higher) processor machines.^[21] Java 6 is also supported by 32-bit machines running Mac OS X 10.6 (Snow Leopard).

Java 5 updates

Java SE 6

Codename Mustang. As of the version released on December 11, 2006, Sun replaced the name "J2SE" with Java SE and dropped the ".0" from the version number.^[22] Internal numbering for developers remains 1.6.0.^[23] 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.

Major changes included in this version:^[24][25]

• Support for older Win9x versions dropped; unofficially, Java 6 Update 7 was 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,^[26][27] 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).^[28]
• 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).
• JVM improvements include: synchronization and compiler performance optimizations, new algorithms and upgrades to existing garbage collection algorithms, and application start-up performance.

Java 6 reached the end of its supported life in February 2013, at which time all public updates, including security updates, were scheduled to be stopped.^[29][30] Oracle released two more update to Java 6 in March and April 2013, which patched some security vulnerabilities.^[31][32]

Java 6 updates

After Java 6 release, Sun, and later Oracle, released several updates which, while not changing any public API, enhanced end-user usability or fixed bugs.^[33] As of January 2016 Java 6 (and earlier) versions are no longer available for download from Oracle.^[34]

Java SE 7

Java 7 (codename Dolphin^[102]) is a major update that was launched on July 7, 2011^[103] and was made available for developers on July 28, 2011.^[104] The development period was organized into thirteen milestones; on June 6, 2011, the last of the thirteen milestones was finished.^[105][106] On average, 8 builds (which generally included enhancements and bug fixes) were released per milestone. The feature list at the OpenJDK 7 project lists many of the changes.

Additions in Java 7 include:^[107]

• JVM support for dynamic languages, with the new invokedynamic bytecode under JSR-292,^[108] following the prototyping work currently done on the Multi Language Virtual Machine
• Compressed 64-bit pointers^[109] (available in Java 6 with -XX:+UseCompressedOops)^[110]
• These small language changes (grouped under a project named Coin):^[111]

• Strings in switch^[112]
• Automatic resource management in try-statement^[113]
• Improved type inference for generic instance creation, aka the diamond operator <>^[114]
• Simplified varargs method declaration^[115]
• Binary integer literals^[116]
• Allowing underscores in numeric literals^[117]
• Catching multiple exception types and rethrowing exceptions with improved type checking^[118]

• Concurrency utilities under JSR 166^[119]
• New file I/O library (defined by JSR 203) adding support for multiple file systems, file metadata and symbolic links. The new packages are java.nio.file, java.nio.file.attribute and java.nio.file.spi^[120][121]
• Timsort is used to sort collections and arrays of objects instead of merge sort
• Library-level support for elliptic curve cryptography algorithms
• An XRender pipeline for Java 2D, which improves handling of features specific to modern GPUs
• New platform APIs for the graphics features originally implemented in version 6u10 as unsupported APIs^[122]
• Enhanced library-level support for new network protocols, including SCTP and Sockets Direct Protocol
• Upstream updates to XML and Unicode
• Java Deployment Rulesets^[123]

Lambda (Java's implementation of lambda functions), Jigsaw (Java's implementation of modules), and part of Coin were dropped from Java 7, and released as part of Java 8 (except for Jigsaw, which will be in Java 9).^[124][125]

Java 7 was the default version to download on java.com from April 2012 until Java 8 was released.^[126]

Java 7 updates

Oracle issued public updates to the Java 7 family on a quarterly basis^[127] until April 2015 when the product reached the end of its support lifecycle.^[34][128]

Java SE 8

Java 8 was released on 18 March 2014,^[178][179] and included some features that were planned for Java 7 but later deferred.^[180]

Work on features was organized in terms of JDK Enhancement Proposals (JEPs).^[181]

• JSR 335, JEP 126: Language-level support for lambda expressions (officially, lambda expressions; unofficially, closures) under Project Lambda^[182] and default methods (virtual extension methods)^{[183][184][185]} which allow the addition of methods to interfaces without breaking existing implementations. There was an ongoing debate in the Java community on whether to add support for lambda expressions.^[186][187] Sun later declared that lambda expressions would be included in Java and asked for community input to refine the feature.^[188] Supporting lambda expressions also allows the performance of functional-style operations on streams of elements, such as MapReduce-inspired transformations on collections. Default methods allow an author of an API to add new methods to an interface without breaking the old code using it. Although it was not their primary intent,^[183] default methods also allow multiple inheritance of behavior (but not state).

• JSR 223, JEP 174: Project Nashorn, a JavaScript runtime which allows developers to embed JavaScript code within applications
• JSR 308, JEP 104: Annotation on Java Types^[189]
• Unsigned Integer Arithmetic^[190]
• JSR 337, JEP 120: Repeating annotations^[191]
• JSR 310, JEP 150: Date and Time API^[192]
• JEP 178: Statically-linked JNI libraries^[193]
• JEP 153: Launch JavaFX applications (direct launching of JavaFX application JARs)^[194]
• JEP 122: Remove the permanent generation^[195]

Java 8 is not supported on Windows XP^[196] but as of JDK 8 update 25, it can still be installed and run under Windows XP.^[197] Previous updates of JDK 8 could be run under XP, but had to be installed after a forced installation by directly unzipping files from the installation executable.

From October 2014, Java 8 has been the default version to download from the official website.^[198]

Java 8 updates

Java SE 9

At JavaOne 2011, Oracle discussed features they hope to have in a 2016 release of Java 9,^[215] including better support for multi-gigabyte heaps, better native code integration, and a self-tuning JVM.^[216] In early 2016 the release of Java 9 was rescheduled for March 2017.^[217]

• JSR 294: Modularization of the JDK under Project Jigsaw (Java Module System)^{[125][218][219]}
• JSR 354: Money and Currency API^[220][221]
• JEP 222: jshell: The Java Shell (a Java REPL)^[222][223]

There are plans to add automatic parallelization using OpenCL.^[1][224]

Work is under way to make the Java implementation of Reactive Streams part of Java 9: Doug Lea, leader of JSR 166, has proposed^[225] a new Flow class^[226] that will include the interfaces currently provided by Reactive Streams.^[227][228]

Java SE 10

There is speculation of introducing objects without identity (value types),^[229][230] as well as moving towards 64-bit addressable arrays to support large data sets somewhere around 2018.^[1]

Implementations

OpenJDK is a free and open source implementation of the Java Platform, Standard Edition (Java SE).

Before OpenJDK, several Free Java implementations were made by companies and groups such as Apache Harmony. IBM also provides Java implementations,^[231] and RedHat provides it through the IcedTea project: a build and integration project for OpenJDK.

References

External links

• Official Java SE Downloads
• Early history of Java
• Full list of changes for J2SE 1.3
• Full list of changes for J2SE 1.4
• Full list of changes for J2SE 5.0
• Full list of changes for Java SE 6
• Mustang development site for Java SE 6
• Java SE 7 release notes
• Sun Java Supported versions and EOL
• Downloads archive for older version of Java

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