The Java™ Native Interface Programmer’s Guide and Specification

THE Java™ Native Interface (JNI) is a powerful feature of the Java platform. Applications that use the JNI can incorporate native code written in programming languages such as C and C++, as well as code written in the Java programming language. The JNI allows programmers to take advantage of the power of the Java
platform, without having to abandon their investments in legacy code. Because the JNI is a part of the Java platform, programmers can address interoperability issues once, and expect their solution to work with all implementations of the Java platform.