使用java Stream获取总和、平均值和排序

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
int sum = numbers.stream().mapToInt(Integer::intValue).sum();
System.out.println("总和：" + sum);

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
OptionalDouble average = numbers.stream().mapToInt(Integer::intValue).average();
if (average.isPresent()) {
    System.out.println("平均值：" + average.getAsDouble());
} else {
    System.out.println("无法计算平均值");
}

List<Integer> numbers = Arrays.asList(5, 3, 1, 4, 2);
List<Integer> sortedNumbers = numbers.stream().sorted().collect(Collectors.toList());
System.out.println("排序结果：" + sortedNumbers);