I thought that: for any one-method interface, Java knows how to cast a lambda expression to an instance of the interface, even without this annotation.
orenovadia, your right: the annotation is not needed.
The @FunctionalInterface annotation enables the compiler to report an error if the interface is not a functional interface, i.e. it has exactly one abstract method. Beside that, it communicates the intend that the interface is a functional interface to the reader.
Thanks for the post Erik.
What does the
@FunctionalInterfacedo?I thought that: for any one-method interface, Java knows how to cast a lambda expression to an instance of the interface, even without this annotation.
orenovadia, your right: the annotation is not needed.
The
@FunctionalInterfaceannotation enables the compiler to report an error if the interface is not a functional interface, i.e. it has exactly one abstract method. Beside that, it communicates the intend that the interface is a functional interface to the reader.Got it, thank you!