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 (Google), SE (OpenJDK and Oracle), MicroEJ. These packages (java.* 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 (Alljoyn, OSGi, Eclipse, JCP, E-S-R, etc.).

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

APIs

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.
Association for the standardization of embedded platforms	E-S-R consortium	here
Java Data Objects	JDO	A specification of Java object persistence.
Android API	Google	here
JavaHelp		A full-featured, extensible help system that enables you to incorporate online help in applets, components, applications, operating systems, and devices.	available here
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.
Jakarta Persistence	JPA	A specification for object-relational mapping.	available here
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 USB for Windows	(none)	A USB communication of Java applications	available here
RestFB	(none)	Facebook API wrapper in Java.	available here
Twitter4j	(none)	Java library for the Twitter API	available here
Discord Java API	JDA	Java library for the Discord API	available here

Name	Acronym	Java package(s) that contain the API
Jakarta Activation	JAF	`jakarta.activation`
Jakarta Mail	(none)	`jakarta.mail`
Jakarta Messaging	JMS	`jakarta.jms`
Jakarta Faces	JSF	`jakarta.faces`

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

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

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 (available here)

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 (RTSJ) have emerged, including a reference implementation from Timesys, IBM's WebSphere Real Time, Sun Microsystems's Java SE Real-Time Systems,^[1] Aonix PERC or JamaicaVM from aicas.

The RTSJ addressed the critical issues by mandating a minimum (only two) specification for the threading model (and allowing other models to be plugged into the VM) 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 (RTSJ) 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