This inspection reports stream API call chains which can be simplified. It allows to avoid creating redundant temporary objects when traversing a collection.

The following call chains are replaced by this inspection:

Collection.stream().forEach() → Collection.forEach()
Collection.stream().forEachOrdered() → Collection.forEach()
Collection.stream().count() → Collection.size()
Arrays.asList().stream() → Arrays.stream() or Stream.of()
Collections.singleton().stream() → Stream.of()
Collections.singletonList().stream() → Stream.of()
Collections.emptyList().stream() → Stream.empty()
Collections.emptySet().stream() → Stream.empty()
Stream.collect(Collectors.counting()) → Stream.count()
Stream.collect(Collectors.maxBy()) → Stream.max()
Stream.collect(Collectors.minBy()) → Stream.min()
Stream.collect(Collectors.mapping()) → Stream.map().collect()
Stream.collect(Collectors.reducing()) → Stream.reduce() or Stream.map().reduce()
Stream.collect(Collectors.summingInt()) → Stream.mapToInt().sum()
Stream.collect(Collectors.summingLong()) → Stream.mapToLong().sum()
Stream.collect(Collectors.summingDouble()) → Stream.mapToDouble().sum()

Note that the replacements semantic may have minor difference in some cases. For example, Collections.synchronizedList(...).stream().forEach() is not synchronized while Collections.synchronizedList(...).forEach() is synchronized. Or collect(Collectors.maxBy()) would return an empty Optional if the resulting element is null while Stream.max() will throw NullPointerException in this case.