how to find maximum value from a Integer using stream in java 8?

Question

I have a list of Integer list and from the list.stream() I want the maximum value. What is the simplest way? Do I need comparator?

Answer 1

You may either convert the stream to IntStream:

OptionalInt max = list.stream().mapToInt(Integer::intValue).max();

Or specify the natural order comparator:

Optional<Integer> max = list.stream().max(Comparator.naturalOrder());

Or use reduce operation:

Optional<Integer> max = list.stream().reduce(Integer::max);

Or use collector:

Optional<Integer> max = list.stream().collect(Collectors.maxBy(Comparator.naturalOrder()));

Or use IntSummaryStatistics:

int max = list.stream().collect(Collectors.summarizingInt(Integer::intValue)).getMax();

Answer 2

Another version could be:

int maxUsingCollectorsReduce = list.stream().collect(Collectors.reducing(Integer::max)).get();

Answer 3

With stream and reduce

Optional<Integer> max = list.stream().reduce(Math::max);

Answer 4

int max = list.stream().reduce(Integer.MIN_VALUE, (a, b) -> Integer.max(a, b));

Answer 5

You could use int max= Stream.of(1,2,3,4,5).reduce(0,(a,b)->Math.max(a,b)); works for both positive and negative numbers

Answer 6

int value = list.stream().max(Integer::compareTo).get();
System.out.println("value  :"+value );