Java Collection Utils - ashishranjandev/developer-wiki GitHub Wiki

List<String> result = IterableUtils.toList(iterable);

List<String> result = IteratorUtils.toList(iterator);

list.sort(Comparator.comparing(AnObject::getAttr));

// Sorting in reverse order
Comparator<Employee> employeeNameComparator
      = Comparator.comparing(Employee::getName);
    Comparator<Employee> employeeNameComparatorReversed 
      = employeeNameComparator.reversed();

long i = response.getNodes()
                 .stream()
                 .filter(node -> node.getId() != null)
                 .peek(node -> node.setValue("This is the id: " + node.getId()))
                 .count();

integers.values().stream().mapToInt(Integer::intValue).sum();

LongAdder a = new LongAdder();
map.values().parallelStream().forEach(a::add);
sum = a.intValue();

// Creating a map of Books with Release Year as the Key
books.stream().collect(
      Collectors.toMap(Book::getReleaseYear, Function.identity()));

Map<String, Long> counted = list.stream()
            .collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));