The code fragment is using the stream methods allMatch, anyMatch, noneMatch, and findFirst on a list of strings called specialDays. These methods are used to perform matching operations on the elements of a stream, such as checking if all, any, or none of the elements satisfy a given predicate, or finding the first element that matches a predicate1. The predicate in this case is that the string equals “Labour” or “Halloween”. The output will be:
False: because not all of the elements in specialDays are equal to “Labour” or “Halloween”.
true: because at least one of the elements in specialDays is equal to “Labour” or “Halloween”.
true: because none of the elements in specialDays are equal to both “Labour” and “Halloween”.
Optional[NewYear]: because the first element in specialDays that matches the predicate is “NewYear”, and the findFirst method returns an Optional object that may or may not contain a non-null value2.
References: Stream (Java SE 17 & JDK 17), Optional (Java SE 17 & JDK 17)
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