For an introduction to Java interfaces, including the difference between classes and interfaces, see my Java 101 tutorial Working with interfaces in Java. Nesting interfaces in classes ...

There are over 40 functional interfaces listed in the java.util.functions package, which can make the prospect of functional programming in Java a somewhat daunting task.

Java's interface language feature often puzzles newcomers to this language. Jeff eliminates this mystery by presenting the six roles that interfaces play in the Java language.

In 2018, a large number of readers were drawn to Java developer tutorials on a variety of topics from RESTful development to continuous delivery with Jenkins CI.