The Java Native Interface (JNI) comes with the standard Java Development Kit (JDK) from Sun Microsystems. It permits Java programmers to integrate native code (currently C and C++) into their Java applications. This article will focus on how to make use of the JNI and will provide a few examples illustrating the usefulness of this feature. Although a native method system was included with the JDK 1.0 release, this article is concerned with the JDK 1.1 JNI which has several new features, and is much cleaner than the previous release.