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

The example code below shows how to use Java’s DirectoryStream in a method to list the files of a directory: public Set<String> listFilesUsingDirectoryStream(String dir) throws IOException { ...

Dark Knight ‘s response indicates how to use Java with 7-Zip-JBinding to uncompress a 7z file. I adapt Dark Knight’s Java code into a Groovy script in this post.