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 5.0. 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.

JDK 1.0 (January 23, 1996) (Unsupported)

Initial releaseVersion 1.0 press release, Sun.

JDK 1.1 (February 19, 1997) (Unsupported)

Major additions included:Version 1.1 press release, Sun.

• an extensive retooling of the AWT event model
• inner classes added to the language
• JavaBeans
• JDBC
• RMI

J2SE 1.2 (December 8, 1998) (Unsupported)

Codename Playground. This 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). Major additions included:Version 1.2 press release, Sun.

• strictfp keyword
• reflection which supports Introspection only, no modification at runtime possible.
• 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 (May 8, 2000) (Unsupported)

Codename Kestrel. The most notable changes were:Version 1.3 press release, Sun.Version 1.3 full list of changes, Sun.

• 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
• JavaSound
• Java Naming and Directory Interface (JNDI) included in core libraries (previously available as an extension)
• Java Platform Debugger Architecture (JPDA)