QUICK ANSWER To open and extract JAR files, you can use any file extraction software. This includes the built-in option on Windows or third-party apps like WinRAR or 7-Zip.

The following command enables you to run any Java JAR file on the command line: java -jar jarfilename.jar To use the JAR file opener that comes when you install Java with the JDK, just issue the ...

A JAR file is nothing more than a "standard" .ZIP file. Use a zip-based program, put all your class files and resources inside a .ZIP file. when done, rename it to .JAR.

Here's a quick example of how to use Java's jarsigner to digitially sign JAR files.