The author of material found at this website http://www.jchq.net/certkey/index.htm allows members of the public to use everything free of charge. The material is meant to help examinees pass the Sun Certified Java Programmers (SCJP) exam.
The tutorial material on this website was deliberately designed by the author so examinees can download then print out the content for their personal use. He only requests that those who wish to make use of the content for other purposes contact him first to ask permission.
Section 1 of the content is concerned with Declarations and Access Control.
Section 2 is devoted to Flow Control and Exception Handling.
Section 3 is about Garbage Collection.
Section 4 refers to Language Fundamentals.
Section 5 talks about Operators and Assignments.
Look to Section 6 for content about Overloading, Overriding, Runtime Type and Object Orientation.
Section 7 discusses Threads.
Section 8 is about the java.lang package while Section 9 is about the java.util package.
The three remaining sections are supposed to be used only by examinees who are interested in the JDK1.2 Certification Exam: Writing listener code; the Java.awt package layout; and the Java.io package.
The author provides answers to Frequently Asked Questions at this link: http://www.jchq.net/faq/jcertfaq.htm.
The author says he used feedback from hundreds of users to create this version of his content. He is only presenting his content in these web pages, rather than pursue publication in hard copies or other publishing formats. This tutorial he created does have its limitations in that it strictly adheres only to the SCJP exam objectives. Fortunately, the author also provides links to other technical books that potential examinees may also use.