Question

我需要制作一个程序，根据用户生成的月降雨量数字并对其进行平均，找出最大值和最小值，找到标准偏差等。我似乎已经将大部分内容都放下了但我的“找到了高于和低于平均水平的数字”似乎不起作用。此外，我无法弄清楚如何让用户选择后再做出选择，然后给予所需的信息。任何帮助将不胜感激。 example output

import java.util.Arrays;
import java.util.Scanner;

public class RainfallAnalyzer {

    public static void main(String[] args) {
        double theRainfall = 0;
        double total = 0;

        Scanner scan = new Scanner(System.in);

        double[] rainfall = new double[12];

        System.out.println("Enter the rainfall measurements for this year: ");

        for (int i = 0; i < rainfall.length; i++) {
            theRainfall = scan.nextDouble();

            rainfall[i] = theRainfall;
            total += rainfall[i];

        }

        int choiceentry = -1;

        loop:
        while (choiceentry !8) {

            System.out.println("1. print all rainfall measurements");
            System.out.println("2. print the avererage rainfall");
            System.out.println("3. print the maximum and minimum rainfall             measurements");
            System.out.println("4. print the number of months above average rainfall");
            System.out.println("5. print the number of months below average rainfall");
            System.out.println("6. print the median rainfall measurement");
            System.out.println("7. print the standard deviation");
            System.out.println("8. exit");

            if (scan.hasNextInt()) {
                choiceentry = scan.nextInt();
            }

            switch (choiceentry) {
                case 1:
                    for (int i = 0; i < rainfall.length; i++) {
                        System.out.println("Month # " + (i + 1) + ": " + rainfall[i]);
                    }
                    break loop;
                case 2:
                    total = total / 12;
                    System.out.println("This year's average rainfall: " + total);
                    break loop;

                case 3:
                    Arrays.sort(rainfall);
                    System.out.println("Min value " + rainfall[0]);
                    System.out.println("Max value " + rainfall[rainfall.length - 1]);
                    break loop;

                case 4:
                    int numRainfallAbove = 0;
                    for (int i = 0; i < rainfall.length; i++) {
                        if (rainfall[i] >= avg) {
                            numRainfallAbove++;
                        } else {
                        }
                    }
                    System.out.println("Number of months above the average rainfall:   " + numRainfallAbove);
                    break loop;

                case 5:
                    int numRainfallBelow = 0;
                    for (int i = 0; i < rainfall.length; i++) {
                        if (rainfall[i] <= total) {
                            numRainfallBelow++;
                        } else {
                        }
                    }
                    System.out.println("Number of months below the average rainfall: " + numRainfallBelow);
                    break loop;

                case 6:
                    double median;
                    if (rainfall.length % 2 == 0) {
                        median = ((double) rainfall[rainfall.length / 2] + (double) rainfall[rainfall.length / 2 - 1]) / 2;
                    } else {
                        median = (double) rainfall[rainfall.length / 2];
                    }

                    System.out.println("This year's median rainfall: " + median);

                    break loop;

                case 7:
                    double theDeviation = deviation(rainfall, total);
                    System.out.println("The standard deviation is " + theDeviation);
                    break loop;

            }

        }

    }

    public static double deviation(double[] rainfall, double total) {
        double endResult = 0;
        double temporary = 0;
        double arraySum = 0;
        double average = total;
        double sum = 0;

        for (int i = 0; i < rainfall.length; i++) {
            sum += Math.pow((rainfall[i] - average), 2);
        }

        temporary = sum / (rainfall.length - 1);
        endResult = Math.sqrt(temporary);
        return endResult;
    }
}

Answer 1

更改案例4中的代码：

null

对此：

int numRainfallAbove = 0;
for(int i = 0; i < rainfall.length; i++){
if(rainfall[i] >= total){
numRainfallAbove++;
} else{}
}
System.out.println("Number of months above the average rainfall:   "+numRainfallAbove);
break loop;

问题在于您将月降雨量与总数进行比较而不是平均值。您需要为您的＆＃34;月份降雨量低于平均水平的月份做类似的事情。

只要用户不退出，要让它继续要求更多选择，请将while循环更改为：

int numRainfallAbove = 0; double avg = total / 12; for (int i = 0; i < rainfall.length; i++) { if (rainfall[i] >= avg) { numRainfallAbove++; } } System.out.println("Number of months above the average rainfall: " + numRainfallAbove); break loop;

除了与您的问题没有直接关系的旁边，请尝试在发布时正确缩进代码，并且不要使用goto语句或指向标签的中断。

Answer 2

此外，我无法弄清楚如何让用户选择后再进行其他选择，然后获得所需的信息。

你编写代码的方式是（实际上）

  loop: while not a valid choice:
    get a choice
    if it is valid choice":
      act on it 
      break out of loop

（注意“腰带和括号”的方式，你终止循环是......不必要的。最终将终止条件置于while条件仅。）< / p>

所以你真正需要的是一种方式让用户说“我想立即停止”。所以你可以做出另一个选择，或者你可以说需要无效的选择。

然后你需要改变循环来说

 while a valid choice:

或

 while not the stop choice (or condition):

有一点，您是否考虑过如果用户输入“STOP”或其他不是数字的内容会发生什么？试试吧。然后尝试解释实际发生的事情。

选择菜单和用户生成的输入有问题

2 个答案: