Java J2ee Planet

-- A JAR file (or J ava Ar chive) is a ZIP file, file that contains an optional META-INF directory, used to distribute a set of Java classes and interfaces . The java compiler and run-time can search for classes in JAR files. The classes in a JAR file must be under the right directory that is "directory name = package name". To include a JAR file in the class search path, the classpath points to the JAR itself, not the directory that contains the JAR. For example, you have a JAR myLibs.jar in directory /myLibs . To have the Java compiler look for classes in this jar, you need to specify: javac -classpath /myLibs/myLibs.jar ... and not directly point to the directory myLibs References Packaging Programs in JAR Files Java Archive (JAR) Files JAR File Specification

JAR files = collection of class files WAR files = collection of class, JSP, XML files EAR files = collection of JAR, WAR, and EJBs The JAR file is a Java Archive. The WAR file is a Web Archive. And finally, the EAR file is an Enterprise Archive.