JAR

JAR is an acronym for Java Archive. It typically contains Java class files and a manifest which provides meta-information. Jar files are the standard way to distribute Java libraries, applets, and applications. They are compressed using zip.

The Java tutorial has information on how to use Jars.

To create a jar file:

• use the jar program included in every Java JDK.
• use the jar task for Apache Ant.
• use WinZip or any other zip compression utility.
• use Java! The Java runtime includes powerful zip and jar tools. It is possible to create a Java program or servlet that jars classes when executed. A constructed JAR file could be useful for Applets.

Sometimes a JAR file is not appropriate for distributing a Java application. All of these formats are similar to Jar, but with a different purpose:

• Web applications are distributed as WAR files, which include classes and servlets, JSP and HTML pages, and meta-information in XML.
• Enterprise applications are distributed as EAR files.
• Services are distributed as SAR files.

Open source utilities

• http://jar-plug.sourceforge.net/
• http://www.jarspy.org/
• http://jarbrowser.sourceforge.net/
• http://one-jar.sourceforge.net/
• http://genjar.sourceforge.net/
• http://classworlds.codehaus.org/uberjar.html

Also See

• (Oct 2003) JAR files revealed - Explore the power of the JAR file format
• (Jan 2003) Reading files from Java Archives (JARs)
• (Nov 2001) Java Tip 120: Execute self-extracting JARs - Create easy-to-use, cross-platform Java Archives
• (Jan 2001) Controlling Package Access With Sealed JAR Files

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