Features Roadmap

Packaging Your Java Programs

The JAR file format and Java Extension Mechanism give you convenient and efficient ways to package and install Java programs.

Java ARchive (JAR) File Format

Java ARchive (JAR) file format lets you bundle multiple class files and the associated resources in a single archive file that can be easily downloaded, emailed, or stored in one convenient package.

In JDK 1.2, the JAR file format has new functionality for updating JAR files, provides new standard APIs for reading and writing JAR files, and supports the use of JAR files in the extensions mechanism.

Java Extension Mechanism

JDK 1.2 supports extensions, which are packages of Java classes (and any associated native code) that application developers can use to extend the functionality of the core platform. The extension mechanism allows the Java VM to use the extension classes in much the same way as the Java VM uses the system classes. The extension mechanism also provides a way to retrieve extensions from URLs when they are not available as part of the JDK or Java Runtime Environment (JRE).

Extensions are packaged as JAR files and installed in the /lib/ext directory of the JDK or JRE. When installed in the /lib/ext directory, extensions can be used by applets and applications without being explicitly included in the class path.

Features Roadmap