NullPointerException if empty stream is empty

Question

I need to define max minutes from set my code

 carWashBoxSet.
                stream().
                filter(p -> p.getOrderTime() != null).
                map(t -> t.getOrderTime()).
                max(Date::compareTo).
                get().
                getMinutes();

The problem is if carWashBoxSet empty i get null pointer exeption, is it any to use smth like stream.ifNonEpty().Orelse() ?

Answer 1

well i highly recommend to not use .get() without .isPresent() , because when the optional is empty, you will create a NoSuchElementException.

To bypass this i would map the getMinutes() at the end, and add an .orElse() or .orElseGet() depending on what you expect as an alternative.

carWashBoxSet.stream()
            .filter(p -> p.getOrderTime() != null)
            .map(t -> t.getOrderTime())
            .max(Date::compareTo)
            .map(boxSet -> boxSet.getMinutes())
            .orElse(/*another value*/);

if you do not expect an alternative and want to just process this value somehow, without further usage .ifPresent() can also be a good choice.

carWashBoxSet.stream()
            .filter(p -> p.getOrderTime() != null)
            .map(t -> t.getOrderTime())
            .max(Date::compareTo)
            .map(boxSet -> boxSet.getMinutes())
            .ifPresent( minutes -> System.out.println(minutes));