In this Java 101 tutorial, I’ve explained how interfaces differ from classes, and showed you how to declare, implement, and extend interfaces in your Java programs.

See the Java 101 Java interfaces tutorial for a more in-depth introduction to using interfaces in your Java programs, including where and where not to use default, static, and private methods.

There is a reason why Java method modifiers exist. If you call public methods internally and don't understand why, your developers could face major class issues.

Also known as the Java 8 Predicate -- which stems from the JDK version where functional programming was introduced to developers -- this simple interface defines five methods, although only the Java ...