update link (#2725)

free-programming-books.md

@@ -1349,7 +1349,7 @@ Kerridge (PDF) (Just fill the fields with any values)
 * [Core Servlets and JavaServer Pages, 2nd Ed. (2003)](http://pdf.coreservlets.com) - Marty Hall and Larry Brown
 * [Data Structures in Java for the Principled Programmer (2007)](http://dept.cs.williams.edu/~bailey/JavaStructures/Book_files/JavaStructures.pdf) - Duane A. Bailey (PDF)
 * [Google's Java Style Guide](https://google.github.io/styleguide/javaguide.html)
-* [Introduction to Computer science using Java](http://chortle.ccsu.edu/java5/index.html) - Bradley Kjell
+* [Introduction to Computer science using Java](http://www.programmedlessons.org/Java9/index.html) - Bradley Kjell
 * [Introduction to Programming in Java](http://introcs.cs.princeton.edu/java/home/) - Robert Sedgewick and Kevin Wayne
 * [Introduction to Programming Using Java](http://math.hws.edu/javanotes/) - David J. Eck
 * [Java Application Development on Linux (2005)](https://ptgmedia.pearsoncmg.com/images/013143697X/downloads/013143697X_book.pdf) - Carl Albing and Michael Schwarz (PDF)