Java Class Library

This article uses bare URLs, which are uninformative and vulnerable to link rot. Please consider converting them to full citations to ensure the article remains verifiable and maintains a consistent citation style. Several templates and tools are available to assist in formatting, such as reFill (documentation) and Citation bot (documentation). (August 2022) (Learn how and when to remove this template message)

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Java Class Library" – news · newspapers · books · scholar · JSTOR (August 2011) (Learn how and when to remove this template message)

The Java Class Library (JCL) is a set of

• Like other
  container classes and regular expression
  processing.
• The library provides an abstract interface to tasks that would normally depend heavily on the hardware and operating system, such as
  network access and file
  access.
• Some underlying platforms may not support all of the features a Java application expects. In these cases, the library implementation can either emulate those features or provide a consistent way to check for the presence of a specific feature.

JCL is almost entirely written in Java, except for the parts that need direct access to the hardware and operating system (such as for I/O or bitmap graphics). The classes that give access to these functions commonly use Java Native Interface wrappers to access operating system APIs.

Almost all of JCL is stored in a single

The

Any Java implementation must pass the Java Technology Compatibility Kit tests for compliance, which includes JCL tests.

Main features

JCL Features are accessed through

• java.lang contains fundamental classes and
  runtime system
  .
• SCTP is available through com.sun.nio.sctp
  .
• Mathematics package: java.math
  provides mathematical expressions and evaluation, as well as arbitrary-precision decimal and integer number datatypes.
• logging and data compression
  .
• Swing package (javax.swing) is built on AWT and provides a platform-independent widget toolkit, as well as a pluggable look and feel
  . It also deals with editable and non-editable text components.
• Sound: interfaces and classes for reading, writing, sequencing, and synthesizing of sound data.
• Text: java.text deals with text, dates, numbers and messages.
• Image package: java.awt.image and javax.imageio provide APIs to write, read, and modify images.
• JAX-WS
  .
• Security is provided by java.security and encryption services are provided by javax.crypto.
• Databases: access to SQL databases via java.sql
• Access to Scripting engines: The javax.script package gives access to any conforming Scripting language.
• Applets: java.applet allows applications to be downloaded over a network and run within a guarded sandbox
• Java Beans: java.beans
  provides ways to manipulate reusable components.
• Introspection and reflection: java.lang.Class represents a class, but other classes such as Method and Constructor are available in java.lang.reflect.

Licensing

Prior licenses

Before the release of OpenJDK, the JDK was based on a proprietary license.

Following their promise to release a fully buildable

Until December 2010, the remaining encumbered part of the JDK was made available by Sun then Oracle as Binary Plugs^[5] which were required to build the JDK but not necessary to run it. as of May 2007^[update], the only part of the Class library that remained proprietary and closed-source (4% as of May 2007^[update] for OpenJDK 7,^[6] and less than 1% as of May 2008^[update] and OpenJDK 6^[7][8]) was^[9] the SNMP implementation.^[10]

Since the first May 2007 release, Sun, with the help of the community, released as open-source or replaced with open-source alternatives almost all the encumbered code:

• All the audio engine code, including the
  software synthesizer, became open source.^[10][11] The closed-source software synthesizer has been replaced by a new synthesizer developed specifically for OpenJDK called Gervill,^[12]
• All cryptography classes were released as open-source,^[13]
• The code that scales and rasterizes fonts uses open source FreeType^[14][15][16]
• The native
  LittleCMS.^[15]
  There is a pluggable layer in the JDK, so that the commercial release of Java can use the original, proprietary color management system and OpenJDK can use LittleCMS.
• The anti-aliasing graphics rasterizer code uses the open source Pisces renderer used in the phoneME project.^[15][17][18]
• The JavaScript plugin is open source (the JavaScript engine itself was open source from the beginning).^[19]

Open source release

Beginning in December 2010, all the so-called binary plugs were replaced by

GNU Classpath is the other main free software class library for Java. Contrary to other implementations, it only implements the Class Library, and is used by many free Java runtimes (like Kaffe, SableVM, JamVM).

Apache Harmony was another free software class library. Its aim was to implement the other parts of the Java stack (Virtual Machine, Compiler, and other tools required for any Java implementation).

See also

• Java Platform, Standard Edition
• List of Java APIs
• OpenJDK
• Free Java implementations
• Standard library
• Java applet

References

External links

• Java SE Main page
• Java SE 19 API Javadocs
• Java SE API documentation
• Java software development kits (status as of August 2006^[update]):
  • 1.7 (early development)
  • 1.6 (stable, current)
  • 1.5 (stable)
  • 1.4 (stable)
  • 1.3 (obsolete)