Rogers Cadenhead is an experienced software developer who has written more than 30 books on programming and web publishing, including Sams Teach Yourself Java in 24 Hours and Absolute Beginner’s Guide to Minecraft Mods Programming. He creates applications on the ServiceNow cloud platform, using Java and JavaScript. He maintains this book’s official website, at www.java21days.com, and can be contacted on Twitter at @rcade and on his weblog, at http://workbench.cadenhead.org.