List of Java APIs
- the official core Java API, contained in the JDK or JRE, of one of the editions of the Java Platform. The three editions of the Java Platform are Java ME (Micro edition), Java SE (Standard edition), and Java EE (Enterprise edition).
- optional official APIs that can be downloaded separately. The specification of these APIs are defined according to a Java Specification Request (JSR), and sometimes some of these APIs are later included in the core APIs of the platform (the most notable example of this kind is Swing).
- unofficial APIs, developed by third parties, but not related to any JSRs.
Third-parties can freely implement any JSR specifications for an official API (even for the core API of the language), providing that they conform to the Technology Compatibility Kit (TCK) for this JSR (the TCK is a suite of tests that checks conformance of implementations for a JSR). The result of this freedom is that many official APIs have more implementations than the Sun's Reference implementation (RI).
Official APIs 
Java Platform, Standard Edition (Java SE) 
|Name||Acronym||Description and Version History||Available from|
|Java Advanced Imaging||JAI||A set of interfaces that support a high-level programming model allowing to manipulate images easily.|
|Java Data Objects||JDO||A specification of Java object persistence.|
|JavaHelp||A full-featured, extensible help system that enables you to incorporate online help in applets, components, applications, operating systems, and devices.|
|Java Media Framework||JMF||An API that enables audio, video and other time-based media to be added to Java applications and applets.|
|Java Naming and Directory Interface||JNDI||An API for directory services.|
|Java Speech API||JSAPI||This API allows for speech synthesis and speech recognition.|
|Java 3D||J3D||A scene graph-based 3D API.||available here|
|Java OpenGL||JOGL||A wrapper library for OpenGL.||available here|
|Java Mail||(none)||A framework to build mail and messaging applications||available here|
|Java USB for Windows||(none)||A USB communication of Java applications||available here|
Java Platform, Enterprise Edition (Java EE) 
Bundled APIs (part of standard download) 
|Name||Acronym||Java package(s) that contain the API|
|Java Message Service||JMS|
Optional APIs (downloaded separately) 
|Java API for XML-Based RPC||JAX-RPC||available here|
|XQuery API for Java||XQJ||here and here|
Java Platform, Micro Edition (Java ME) 
|Connected Limited Device Configuration||CLDC||Reference implementation is available here|
|Java Telephony API||available here|
Unofficial APIs (Released by third parties) 
This list is very incomplete, as the number of APIs available for the Java platform is overwhelming.
- Rich Client Platforms
- Office_compliant libraries
- LZMA SDK, the Java implementation of the SDK used by the popular 7-Zip file archive software (available here)
- Game engines
- Real-time libraries
- Windowing libraries
- Standard Widget Toolkit (SWT)
- Physics Libraries