import com.github.underscore.Underscore; List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5); Underscore.each(numbers, (Integer number) -> { int square = number * number; System.out.println(square); }); List<Integer> evenNumbers = Underscore.filter(numbers, (Integer number) -> number % 2 == 0); Underscore.configure().setReduceDefaultValue(0);