Java Archive (JAR)

JAR files (Java Archive files) are archive files that bundle multiple files into a single compressed package, typically used in the Java programming environment. They are built on the ZIP file format and typically have a .jar file extension. JAR files are widely used for distributing Java applications or libraries.

JAR files are used to package Java classes and associated metadata and resources (like text, images, etc.) into a single file. They are commonly used for distributing [[Java]] applications and libraries.

A JAR file can contain Java class files, Java source files, image files, and other data files. It also contains a manifest file (META-INF/MANIFEST.MF) that specifies metadata about the archive, such as the main class with the main method for executable JARs.

JAR files can be made executable, meaning they can be run as a standalone Java application. The manifest file specifies the entry point of the application, making it possible to run the JAR file by executing java -jar filename.jar.

JAR files simplify the deployment and distribution of Java applications. They bundle all necessary components in a single file, making it easier to transport and use. They support compression, which reduces the size of the application and improves download time.

JAR files are platform-independent, meaning they can be run on any device with a [[Java Runtime Environment (JRE)]]. JAR files can be digitally signed, allowing users to authenticate the source of the JAR and ensuring the integrity of its contents.

In Java development, libraries are often distributed as JAR files. These can be included in the classpath of other Java projects to use the library's functionality. JAR files can be created and extracted using the jar command-line tool provided with the [[Java Development Kit (JDK)]], or with standard ZIP tools.