Java 8 provided a lot of new and very useful features that we can use in our everyday life. In this post I decided make an overview with examples of most commonly used built-in functional interfaces.
I’d like to start from the definition, what is the functional interface? By the definition any interface that has only one abstract method is considered to be a functional interface. Another name for such interfaces is Single Abstract Method interfaces (SAM Interfaces). For instance, Runnable is absolutely legal FI and as you can see it’s annotated now with FunctionalInterface annotation. Continue reading Functional Interfaces Overview