Welcome to Cay Horstmann’s Home Page!

Photo of Cay Horstmann

I grew up in Northern Germany and attended the Christian-Albrechts-Universität in Kiel, a harbor town at the Baltic sea. I received a M.S. in computer science from Syracuse University, and a Ph.D. in mathematics from the University of Michigan in Ann Arbor. I taught computer science at San Jose State University for almost thirty years and held visiting appointments at universities in Germany, Switzerland, Vietnam, and Macao. I was a “serial entrepreneur” before that was a thing, including a stint as VP and CTO of a dot com startup that went from three people in a tiny office to a public company. In my copious spare time I write books and develop online courses for beginning and professional programmers.

I am a Java Champion and ACM Distinguished Member.

Books

For Professional Programmers

For Computer Science Students

Big Java | Brief Java (former title: Java Concepts)
Big Java Late Objects | Java Concepts Late Objects
Big C++ | Brief C++ (former title: C++ for Everyone)
Python for Everyone
OO Design & Patterns

From the Archives

Software

CodeCheck is a convention-over-configuration autograder for Java, Python, C/C++, and many other languages. Now with Parsons puzzles and code tracing
The GridWorld framework was used in the AP CS course as a case study from 2008 until 2013.
Violet is a free, easy to use UML editor.
The traffic jam simulator applet simulates the traffic flow on a freeway and shows how traffic jams are inevitable even at modest loads if too many people don't maintain their speed.
Safe STL is a safe version of the original HP STL implementation.
ChiWriter, an ancient word processor

The March of Progress

1980: C

printf("%10.2f\n", x);

1988: C++

cout << setw(10) << setprecision(2) << fixed << x << endl;

1996: Java 1.0

java.text.NumberFormat formatter = java.text.NumberFormat.getNumberInstance();
formatter.setMinimumFractionDigits(2);
formatter.setMaximumFractionDigits(2);
String s = formatter.format(x);
for (int i = s.length(); i < 10; i++) System.out.print(' ');
System.out.println(s);

2004: Java 5

System.out.printf("%10.2f%n", x);

2008: Scala and Groovy

printf("%10.2f%n", x)

Thanks to Will Iverson for the update. He writes: “Note the lack of semi-colon. Improvement!”

2012: Scala 2.10

println(f"$x%10.2f")

Thanks to Dominik Gruntz for the update, and to Paul Phillips for pointing out that this is the first version that is checked at compile time. Now that's progress.

2023: Java 21

System.out.println(FMT."%10.2f\{x}")

This proposal was withdrawn in 2024.

2023: C++ 23

std::println("{:10.2f}", x);

Thanks to Steve Gilbert for the update.