From 1995 to 1997 he worked at the Sydney University, followed by a position as a senior lecturer at Monash University and, from 2001, a post as an associate professor at the University of Southern Denmark. He worked at the School of Computing at the University of Kent, UK, until February 2017. He is now a professor of computer science at King's College London, where he also occupies the role of vice-dean for education.[6]
Kölling is the lead designer of 'Blue',[7] an object-oriented programming language and integrated environment, BlueJ, and Greenfoot. All are educational development environments aimed at teaching and learning programming. BlueJ and Greenfoot are widely used in many schools and universities.
Kölling co-wrote Objects First with Java with David J. Barnes,[8] and wrote Introduction to Programming with Greenfoot.[9]
On 22 May 2005 Kölling entered the BlueJ website[11] in response to a post on Dan Fernandez's blog (Lead Product Manager – Visual Studio Express). Fernandez described a new feature of Visual Studio 2005 that "helps you understand objects at Design Time, rather than runtime."[12] This feature had striking similarities to how the object test bench functions within BlueJ.
Kölling did not act on the discovery. However, on May 11, 2006 Microsoft attempted to patent[13] the idea. As the object test bench is essential to the way it functions, had Microsoft's patent been granted, it was likely that BlueJ would have had to have been discontinued.
Kölling spoke to Microsoft, namely Jane Prey, and eventually the patent was dropped.[14]
Fernandez posted a response on his blog saying "the patent application was a mistake and one that should not have happened. To fix this, Microsoft will be removing the patent application in question. Our sincere apologies to Michael Kölling and the BlueJ community."[15]
^Bennedsen, Jens; Caspersen, Michael E.; Kölling, Michael (Eds.), Reflections on the Teaching of Programming Series: Lecture Notes in Computer Science, Vol. 4821. Springer, 2008, ISBN978-3-540-77933-9.
^David J. Barnes & Michael Kölling, Objects First with Java: A Practical Introduction using BlueJ, Prentice Hall / Pearson Education, 2008, ISBN0-13-606086-2
^Michael Kölling, Introduction to Programming with Greenfoot: Object-Oriented Programming in Java with Games and Simulations, Pearson Education, August 2009, ISBN978-0-13-603753-8