一次执行多个运算(求和和平均)的java8 reduce

import java.util.Arrays;
import java.util.List;
import java.util.OptionalDouble;

public class Main {
    public static void main(String[] args) {
        List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);

        // 求和
        Optional<Integer> sum = numbers.stream()
                .reduce((a, b) -> a + b);
        if (sum.isPresent()) {
            System.out.println("Sum: " + sum.get());
        } else {
            System.out.println("Sum is not available.");
        }

        // 平均值
        OptionalDouble average = numbers.stream()
                .mapToDouble(Integer::doubleValue)
                .average();
        if (average.isPresent()) {
            System.out.println("Average: " + average.getAsDouble());
        } else {
            System.out.println("Average is not available.");
        }
    }
}

Sum: 15
Average: 3.0