• Implementation and configuration

• Conformance

• Main features

• Licensing

• Prior licenses

• Open source release

• Alternative implementations

• See also

• References

• External links

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), which are instead written in C++.cite-ref-1[1] 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 Java archive file called

"rt.jar" which is provided with JRE and JDK distributions. The Java

Class Library (rt.jar) is located in the default bootstrap classpathcite-ref-2[2]

and does not have to appear in the classpath declared for the

application. The runtime uses the bootstrap class loader to find the

JCL.

The Java Module System (part of the Java 9 release) broke the monolithic

"rt.jar" JAR file and modularized the JCL itself in several modules with

specified dependencies.cite-ref-3[3]