Question

文本文件（myfile.txt）的编号如下：

我可以用Java读取和打印这个文本文件作为字符串标记，我的代码是：

                      File fileName = new File("myfile.txt");         
                      Scanner inFile = new Scanner(fileName);        
                      while (inFile.hasNext())         
                      {         
                      token = inFile.next( ); 

                      System.out.println(token);

                      } 

                    inFile.close();

现在如何在java中获取这些数字的总和？我的意思是SUM（6 + 19 + 20 + 23 + .......... + 111）

Answer 1

使用 int 变量 sum ，并使用scanner.nextInt()提取数字。并在每次迭代时进行添加。

                      File fileName = new File("myfile.txt");         
                      Scanner inFile = new Scanner(fileName);
                       int sum=0;        
                      while (inFile.hasNext())         
                      {         
                           sum+= inFile.nextInt( );     
                      } 
                      System.out.println(sum);

                    inFile.close();

Answer 2

您可以使用Integer.parseInt方法将字符串转换为int。然后将其添加到您需要在外面声明的sum变量。

Scanner inFile = new Scanner(fileName);        
int sum = 0;
while (inFile.hasNext()) {         
    token = inFile.next( ); 

    System.out.println(token);
    sum += Integer.parseInt(token);

}

好吧，如果你正在读取整数值，使用inFile.nextInt()是一个更好的选择。并在while循环中使用inFile.hasNextInt()。

Answer 3

首先使用nextInt()类的Scanner将整数读入List。然后使用“增强型”for循环

在列表中添加每个数字

Answer 4

所以我能够弄清楚我的问题并且很成功，但我仍然希望任何人都可以通过使用teranary运算符来简化这种语法。

import java.util.Scanner;
import java.io.*;
public class Midterm
{
    public static void main(String[]args) throws Exception
    {
     final String FILE = "integers.txt";
     final String RELATIVE_DIRECTORY_FILE = "integers.txt ";
    int positiveNumberCount = 0,
    negativeNumberCount = 0;
    String dataItem;
    double sum = 0;
    double sumForAverage = 0;
    double average = 0;

    File inputFile = new File(RELATIVE_DIRECTORY_FILE);
    if(!inputFile.exists())
    {
        System.out.printf("%n%s%s%s", "The file, ",   RELATIVE_DIRECTORY_FILE, " does not exist");
    }

    if(inputFile.exists())
    {
        System.out.printf("%s%s%s", "The file ", RELATIVE_DIRECTORY_FILE,       "was found");
        Scanner file = new Scanner(inputFile);
        //***if i need to use a delimiter *****
        //file.useDelimiter(",") where in between " "  is my type of delimiter
        while(file.hasNext())
        {



            dataItem = file.nextLine();

            double numericalDataItem = Double.parseDouble(dataItem);

            boolean isPositive = false;
            boolean isNegative = false;

            if(numericalDataItem > 0)
            {
                isPositive = true;
                positiveNumberCount++;
            }
            else if(numericalDataItem < 0)
            {
                isNegative = true;
                negativeNumberCount++;
            }

            sum += Double.parseDouble(dataItem);
            sumForAverage = positiveNumberCount + negativeNumberCount;
            average = sum/sumForAverage;

        } 
        System.out.printf("%n%s%d%n%s%d%n%s%.2f%n%s%.2f", "Positive Number Count: ", positiveNumberCount,
        "Negative Number Count: ", negativeNumberCount, "Sum Of Numbers: ", sum, "Average of Numbers: ", average);
    }
}
}

如何在Java中从文本文件中添加字符串标记号

4 个答案: