import java.util.*; import java.lang.annotation.Annotation; import java.util.function.Function; import java.util.stream.Collectors; import java.util.stream.Stream; abstract class WithAnn { { map((Class ann) -> getAnnotation(ann)); map(this::getAnnotation); } abstract A getAnnotation(Class annotationClass); abstract void map(Function, ? extends R> mapper); } class Test { private void it(final Set> set) { set.forEach((clazz) -> bind(clazz)); } protected void bind(Class clazz) {} }