This week's book giveaway is in the Python forum. We're giving away four copies of High Performance Python for Data Analytics and have Tiago Rodrigues Antao on-line! See this thread for details.
at the page 53 section "Defining a Functional Interface"
in the frame with headline "Applying the @FunctionalInterface Annotation"
Conversely, if a class marked with the @FunctionalInterface
annotation contains more than one abstract method, or no abstract methods at all, then
the compiler will detect this error and not compile.
should be if a interface marked with the @FunctionalInterface