Java - 最高、最低和平均

Question

我刚开始学习，我的一项练习需要帮助。

我需要最终用户输入每个月的降雨量。 然后我需要输出平均降雨量，最高月份和最低月份以及降雨量高于平均水平的月份。

我一直在最高和最低得到相同的数字，我不知道为什么。我正在认真地拔头发。任何帮助将不胜感激。

这是我目前所拥有的：

public class rainfall {

    /**
     * @param args
     */
    public static void main(String[] args) 
    {
    int[]  numgroup;
    numgroup = new int [13];
    ConsoleReader console = new ConsoleReader();
    int highest;
    int lowest;
    int index;
    int tempVal;
    int minMonth;
    int minIndex;
    int maxMonth;
    int maxIndex;


    System.out.println("Welcome to Rainfall");

    for(index = 1; index < 13; index = index + 1)
    {       
        System.out.println("Please enter the rainfall for month " + index);
                tempVal = console.readInt();
                while (tempVal>100 || tempVal<0)
                    {
                    System.out.println("The rating must be within 0...100. Try again");
                    tempVal = console.readInt();
                    }
                numgroup[index] = tempVal;
    }           



    lowest = numgroup[0];


        for(minIndex = 0; minIndex < numgroup.length; minIndex = minIndex + 1);
        {
                if (numgroup[0] < lowest)
                {
                lowest = numgroup[0];
                minMonth = minIndex;
                }
        }

    highest = numgroup[1];


            for(maxIndex = 0; maxIndex < numgroup.length; maxIndex = maxIndex + 1);
            {
                    if (numgroup[1] > highest)
                    {
                    highest = numgroup[1];
                    maxMonth = maxIndex;
                    }
            }


        System.out.println("The average monthly rainfall was ");
        System.out.println("The lowest monthly rainfall was month " + minIndex);
        System.out.println("The highest monthly rainfall was month " + maxIndex);

        System.out.println("Thank you for using Rainfall");

    }


    private static ConsoleReader ConsoleReader() {

        return null;
    }

}

谢谢，

艾米丽

Answer 1

首先，因为这是你的作业，你不应该在 stackoverflow.com 上问它

现在让我们看看你的代码

1. lowest = numgroup[0];

为什么？看来你试图用这个算法来找到最小值：

1.1 假设第一个数字（您认为是 numgroup[0]）是 min（在您的代码中命名为 lowest）
1.2.将其与所有其他数字进行比较，如果任何数字较小，请替换 min（即lowest）。

但是，numgroup[0] 不是您的第一个号码！你像这样开始了你的第一个 for 循环

for(index = 1;...

所以，你的第一个号码是numgroup[1]。

接下来，你的第二个循环开始

for(minIndex = 0;

而索引 0 处的元素甚至都不打算被您使用（我猜）

接下来，判断当前迭代次数是否小于lowest的条件是

if (numgroup[0] < lowest)

它总是将索引 0 处的元素与 lowest 进行比较（我猜）这不是你的意图。

Answer 2

而不是

if (numgroup[0] < lowest)

你必须写

if (numgroup[minIndex] < lowest)

同样的道理

if (numgroup[1] > highest)

应该是

if (numgroup[maxIndex] > highest)

Answer 3

你会的

lowest = numgroup[0]

然后

if (numgroup[0] < lowest)

这永远不会是“真”，因为 numgroup[0] 总是等于最低。相反，您的 if 子句应该类似于 if (numgroup[minIndex] < lowest)。同样的事情也适用于最高。

Answer 4

public static void main(String[] args) 
{
int[] numgroup = new int [12]; // 12 months - 12 elements
ConsoleReader console = new ConsoleReader();
int highest;
int lowest;
int index;
int tempVal;
int minIndex;
int maxIndex;


System.out.println("Welcome to Rainfall");
// Input (index now 0-based)
for(index = 0; index < 12; index = index + 1)
{       
    System.out.println("Please enter the rainfall for month " + index + 1);
    tempVal = console.readInt();
    while (tempVal>100 || tempVal<0)
    {
        System.out.println("The rating must be within 0...100. Try again");
        tempVal = console.readInt();
    }
    numgroup[index] = tempVal;
}           

lowest = numgroup[0];
highest = numgroup[0];
int total = 0.0;
// Loop over data (using 1 loop)
for(index = 0; index < 12; index = index + 1)
{       
    int curr = numgroup[index];
    if (curr < lowest) {
        lowest = curr;
        minIndex = index;
    }
    if (curr > highest) {
        highest = curr;
        maxIndex = index;
    }
     total += curr;
}
float avg = (float)total / numgroup.length;

System.out.println("The average monthly rainfall was " + agv);
// +1 to go from 0-based index to 1-based month
System.out.println("The lowest monthly rainfall was month " + minIndex + 1);
System.out.println("The highest monthly rainfall was month " + maxIndex + 1);

System.out.println("Thank you for using Rainfall");

}

Answer 5

如果您的作业没有限制，请尝试将集合用于最小值/最大值。

Vector<Integer> rainfallData = new Vector<Integer>();
int avg = 0;

for(index = 1; index < 13; index = index + 1)
{       
    System.out.println("Please enter the rainfall for month " + index);
    tempVal = console.readInt();
    while (tempVal>100 || tempVal<0)
    {
        System.out.println("The rating must be within 0...100. Try again");
        tempVal = console.readInt();
    }
   rainfallData.add(tempVal);
   avg+=tempVal; 
}

avg /= rainfallData.size();
int min = Collections.min(rainfallData);
int max = Collections.max(rainfallData);

否则，最小值/最大值应如下所示：

public int min(int[] vals) {
    if( vals==null || vals.length==0} {
           throw new IllegalArgumentException();
    } else if( vals.length == 1 ) {
         return vals[0];
    }
    int min = vals[0]; // Dont initialize with Integer.MAX_VALUE or so
    for(int i = 1; i < vals.length; ++i ) {
        if( vals[i] < min ) {
           min = vals[i];
        }
    } 
    return min;
}

Answer 6

for (index = 0; index < 12; index++) {

}

更改第一个 for 循环和以下

lowest = numgroup[0];

for (minIndex = 0; minIndex < numgroup.length; minIndex = minIndex + 1)
{
    if (numgroup[minIndex] < lowest) {
        lowest = numgroup[minIndex];
    }
}

highest = numgroup[0];

for (maxIndex = 0; maxIndex < numgroup.length; maxIndex = maxIndex + 1)
{
    if (numgroup[maxIndex] > highest) {
         highest = numgroup[maxIndex];
     }
}