This distribution is for the Fourth Edition of the book; files here do not match earlier editions of the Java Cookbook. If you are using an older version, you should check out a different branch in the github repo javasrc.
All the important source code files from The Java Cookbook (plus quite a number that are not covered in the book) are here. Most of these files are Java source code.
All files are Copyright ©. See the accompanying Legal Notice for conditions of use. You can pretty much do what you want with these, including using them commercially, under the terms of the original Berkeley License, which has been approved as an Open Source Initiative conditions-of-use.