List of Java APIs

There are two types of Java programming language application programming interfaces (APIs):

The official core Java API, contained in the Android, SE, MicroEJ. These packages are the core Java language packages, meaning that programmers using the Java language had to use them in order to make any worthwhile use of the Java language.
Optional APIs that can be downloaded separately. The specification of these APIs are defined according to many different organizations in the world.

The following is a partial list of application programming interfaces for Java.

APIs

Name	Acronym	Java package that contain the API
Jakarta Activation	JAF	`jakarta.activation`
Jakarta Mail		`jakarta.mail`
Jakarta Messaging	JMS	`jakarta.jms`
Jakarta Faces	JSF	`jakarta.faces`

Name	Acronym	Available from
Jakarta XML RPC	JAX-RPC	and
XQuery API for Java	XQJ	and

Name	Acronym	Available from
Connected Limited Device Configuration	CLDC	Reference implementation is
Java Telephony API	JTAPI
STM32 Java technology	STM32Java
MicroEJ embedded platform	MicroEJ

Following is a very incomplete list, as the number of APIs available for the Java platform is overwhelming.
;Rich client platforms

;Office_compliant libraries

;Compression

LZMA SDK, the Java implementation of the SDK used by the popular 7-Zip file archive software

;JSON

Jackson (API)

;Game engines

;Real-time libraries
Real time Java is a catch-all term for a combination of technologies that allows programmers to write programs that meet the demands of real-time systems in the Java programming language.
Java's sophisticated memory management, native support for threading and concurrency, type safety,
and relative simplicity have created a demand for its use in many
domains. Its capabilities have been enhanced to support real time
computational needs:

Java supports a strict priority based threading model.
Because Java threads support priorities, Java locking mechanisms support priority inversion avoidance techniques, such as priority inheritance or the priority ceiling protocol.

To overcome typical real time difficulties, the Java Community introduced a specification for real-time Java, JSR001. A number of implementations of the resulting Real-Time Specification for Java have emerged, including a reference implementation from Timesys, IBM's WebSphere Real Time, Sun Microsystems's Java SE Real-Time Systems, Aonix PERC or JamaicaVM from aicas.
The RTSJ addressed the critical issues by mandating a minimum
specification for the threading model and by providing for areas of memory
that are not subject to garbage collection, along with threads that are
not preempt able by the garbage collector. These areas are instead
managed using region-based memory management.

Real-Time Specification for Java

The Real-Time Specification for Java is a set of interfaces and behavioral refinements that enable real-time computer programming in the Java programming language. RTSJ 1.0 was developed as JSR 1 under the Java Community Process, which approved the new standard in November, 2001. RTSJ 2.0 is being developed under JSR 282. A draft version is available at JSR 282 JCP Page. More information can be found at RTSJ 2.0

Javolution

;Windowing libraries

Standard Widget Toolkit

;Physics libraries

JBox2D
JBullet
dyn4j