java 。尝试仅计算正数的平均值，如果未输入正数也会显示一条消息

Question

我正在尝试做一个练习，但无法弄清楚如何仅计算正数的平均值以及如何在未输入正数的情况下显示特定消息。我希望仅在未输入正数时才显示该消息。谢谢

import java.util.Scanner;

public class AverageOfPositiveNumbers {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int entries = 0;
        Double average = 0.0;
        Double sum = 0.0;


        while (true) {
            int number = Integer.valueOf(scanner.nextLine());
            if (number == 0) {
                System.out.println(average);
                break;
            }
            if (number > 0) {

                entries = entries + 1;
                average = sum / entries;
                sum = sum + number;
            }
            if (number < 0) {
                System.out.println("Cannot calculate the average.");
            }

        }

    }
}

Answer 1

您只需要两个变量即可确定平均值。元素的数量(count)以及正值的总和。获取元素后计算平均值。比如，

Scanner scanner = new Scanner(System.in);
int count = 0;
int sum = 0;
while (true) {
    int number = Integer.parseInt(scanner.nextLine());
    if (number == 0) {
        break;
    } else if (number > 0) {
        count++;
        sum += number;
    }
}
if (count > 0) {
    System.out.printf("The average is %.2f%n", sum / (double) count);
} else {
    System.out.println("Cannot calculate the average.");
}