The GoF Design Patterns published in 1998 qualifies as a classic still being taught in universities and recommended as best practice in the industry. In his deep dive session from Devoxx, Venkat Subra ...

Get an overview of design patterns, then use what you've learned to evaluate whether the Composite pattern is a good choice for a particular Java use case ...

Strategy is a fairly simple pattern that serves as an example of how to get your feet wet with the GoF design patterns generally; Visitor is more complex and intermediate in scope.