Java classes forming an application, Applet, or weblet can be bundled up into something that looks very much like a ZIP file. JavaBeans are also packaged in JAR files. In JDK 1.1+ compression is turned on by default and in earlier versions it was always off. It is faster to download a group of classes as a single JAR file since HTTP has high overhead to set up a connection for each file transferred. The tools Jar.exe and jarsigner.exe come bundled with the JDK.
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