Question

我希望有人可以帮助我。

我现在有一个在线Java OOP课程，我的作业差不多完成了，但是我遇到了一个问题，教授没有回复我的电子邮件。

我正在尝试制作一个程序，该程序使用包含日期和温度记录的文件，然后最终输出到一个单独的记录，该记录具有日期，当天的最高温度，当天的最低温度和平均温度那天。我们正在使用数组来跟踪数据。

大多数事情都可以正常工作，但是由于某些原因，某些日子将无法获得正确的最低温度，而是在程序开始时分配初始化数组索引的编号。

在此方面的任何帮助将不胜感激。下面是我的代码，以及程序运行后的数组外观，以及数组运行后的文件外观。

谢谢。

package dow.with.arrays;

import java.util.Arrays;

public class DOWWithArrays
{

    public static void main(String[] args)
    { //start
        InputFile inFile = new InputFile("input.txt");
        OutputFile outFile = new OutputFile("output.txt");

        //INITILIZATION
        int day = 0;
        int temp = 0;
        int[] high = new int[8];         //declares an array of integers for high temps
        int[] low  = new int[8];          //declares an array of integers for low temps
        int[] count = new int[8];        //declares an array of integers for counting days
        int[] total = new int[8];        //declares an array of integers for total temp

        for (day = 0; day < 8; day++) //initilization for the arrays
        {
            high[day] = -999;
            low[day] = 999;
            count[day] = 0;
            total[day] = 0;
        }

        //tells user the DOW Temp program is starting
        System.out.println("DOW Temperature Started. Please wait...");

        System.out.println(Arrays.toString(high)); //GET RID OF THIS BEFORE TURN IN
        System.out.println(Arrays.toString(low)); //GET RID OF THIS BEFORE TURN IN
        System.out.println(Arrays.toString(count)); //GET RID OF THIS BEFORE TURN IN
        System.out.println(Arrays.toString(total)); //GET RID OF THIS BEFORE TURN IN

        while (!inFile.eof())
        { //not the end of file
            day = inFile.readInt(); //read first int
            temp = inFile.readInt(); //read second int

            if (temp > high[day]) //assigns the current highest temperature
            {                     //into the correct place in the high array
                high[day] = temp;
            } else if (temp < low[day])//assigns the current lowest temperature
            {                        //into the correct place in the low array
                low[day] = temp;
            }
            count[day]++; //counts how many temps there are in the specific day
            total[day] = total[day] + temp; //calculates the total temp for each day

        } //now end of file

        for (day = 1; day < 8; day++)
        {
            outFile.writeInt(day);  //write day #
            outFile.writeInt(high[day]);  //write high temp for that day
            outFile.writeInt(low[day]); //write low temp for that day
            outFile.writeInt(total[day] / count[day]); //write average temp for that day
            outFile.writeEOL();   //write end of line
            System.out.println(day);
        } //for

        System.out.println(Arrays.toString(high)); //GET RID OF THIS BEFORE TURN IN
        System.out.println(Arrays.toString(low)); //GET RID OF THIS BEFORE TURN IN
        System.out.println(Arrays.toString(count)); //GET RID OF THIS BEFORE TURN IN
        System.out.println(Arrays.toString(total)); //GET RID OF THIS BEFORE TURN IN

        outFile.close();
        System.out.println("DOW Temperature Completed Sucessfully.");
    } //stop

} //end DOW With Arrays

之前：

[-999, -999, -999, -999, -999, -999, -999, -999]
[999, 999, 999, 999, 999, 999, 999, 999]
[0, 0, 0, 0, 0, 0, 0, 0]
[0, 0, 0, 0, 0, 0, 0, 0]`

之后：

[-999, 62, 56, 70, 61, 59, 77, 55] 
[999, 55, 999, 63, 59, 999, 999, 999] 
[0, 2, 2, 3, 2, 2, 1, 1] 
[0, 117, 110, 200, 120, 108, 77, 55]

之前的文件：

之后的文件：

1 62 55 58 
2 56 999 55 
3 70 63 66 
4 61 59 60 
5 59 999 54 
6 77 999 77 
7 55 999 55

Answer 1

If - Else if ...如果if表达式为true，则else if被忽略。我认为错误在这里：

if (temp > high[day]) //assigns the current highest temperature
{                     //into the correct place in the high array
    high[day] = temp;
} else if (temp < low[day])//assigns the current lowest temperature
{                        //into the correct place in the low array
            low[day] = temp;
}

尝试删除else：

if (temp > high[day]) //assigns the current highest temperature
{                     //into the correct place in the high array
    high[day] = temp;
}

if (temp < low[day])//assigns the current lowest temperature
{                        //into the correct place in the low array
            low[day] = temp;
}

Answer 2

您已经有一个answer from Frighi；我只想指出一些替代方法。

当您第一次遇到一天时，当前代码就会出现问题，因为该代码不会同时高低更新。

您可以通过查看count一天来明确地检测到这一点：如果为零，请同时更新两者：

if (count[day] == 0) {
  low[day] = high[day] = temp;
} else if (temp > high[day]) {
  high[day] = temp;
} else if (temp < low[day]) {
  low[day] = temp;
}

或者，您可以简单地使用min和max，并且没有（明确的）条件：

high[day] = Math.max(high[day], temp);
low[day] = Math.min(low[day], temp);

Answer 3

问题是else；删除它：

if (temp > high[day]) {
    high[day] = temp;
}

if (temp < low[day]) {
    low[day] = temp;
}

请考虑一下，如果一天中只有1个温度，那么它既是最高温度，又是最低温度。

Answer 4

您遇到的问题是确定一天中最低和最高温度的算法。具体来说，这部分：

if (temp > high[day]) //assigns the current highest temperature
{                     //into the correct place in the high array
    high[day] = temp;
} else if (temp < low[day])//assigns the current lowest temperature
{                        //into the correct place in the low array
    low[day] = temp;
}

应该是：

if (temp > high[day]) //assigns the current highest temperature
{                     //into the correct place in the high array
    high[day] = temp;
}

if (temp < low[day])//assigns the current lowest temperature
{                        //into the correct place in the low array
    low[day] = temp;
}

如果您只是通过调试器来跟踪代码中的内容或更好的代码，则可能是您自己想出来的，对于第一种行为是错误的情况，第2天，或更简单的一天， 7。

另外，对于代码的这一部分，请研究Math.min / Math.max函数，以及Integer.MIN_VALUE / Integer.MAX_VALUE和+=。

此外，出于可维护性和可扩展性的原因，您应该尝试找到一种不对程序中的天数进行硬编码的方法。或第一天是1的事实。

Java为数组分配错误的数字

4 个答案: