There is (to date) two articles in Xojo Blog about Design Patterns:
Design Patterns in Xojo: Singleton: Singleton
Design Patterns in Xojo: Observer: Part 1
After a simple search, I found this article: Java Design Patterns. (many advertising popover likes )
There are others like JavaScript Design Patterns - no advertising, but far from intuitive !
What is your feeling about the tutorial from javadesign-patterns.blogspot.fr ?
The blogspot dot-country (.fr above) will certainly change depending on your country (to .com thru .in to ).