Previous | Next | Trail Map | JAR Files | Contents

JAR Files

by Alan Sommerer

The JavaTM Archive (JAR) file format enables you to bundle multiple files into a single archive file. Typically a JAR file will contain the class files and auxiliary resources associated with applets and applications.

Note: The JAR file format was introduced in version 1.1 of the Java Development Kit, and version 1.2 includes several enhancements to JAR file functionality. Unless otherwise noted, features covered in this trail pertain to both versions 1.1 and 1.2. If a feature description or example pertains only to one version, you'll be alerted with an annotation such as "version 1.2."

The JAR file format provides many benefits:

This trail has three lessons:

Using JAR Files: The Basics shows you how to perform basic JAR-file operations, and how to run software that is bundled in JAR files. This lesson also introduces you to the concept of the JAR file's manifest, which plays an important role in more advanced JAR functionality.

Signing and Authenticating JAR Files shows you how to use the JDKTM tools to digitally sign JAR files and verify the signatures of signed JAR files.

Using JAR-related APIs Introduced in 1.2 introduces you to some of the new JAR-handling features in version 1.2 of the Java platform.

The JAR file format is an important part of the Java platform's extension mechanism. You can learn more about that aspect of JAR files in the The Extension Mechanism trail of this tutorial.

Please send comments about this trail to: You feedback is important to us!

Previous | Next | Trail Map | JAR Files | Contents