java - 我程序上的额外 + 标志

Question

我为我的计算机科学类(class)编写了一个程序，它读取一个文件并导入数据，然后只添加数字，但它似乎添加了一个额外的加号。

import java.io.*; //necessary for File and IOException 
import java.util.*; //necessary for Scanner
public class Tester
{
public static void main( String args[] ) throws IOException
   {
    Scanner sf = new Scanner(new File("/Volumes/DVLUP Flash/Numbers.txt"));

    int maxIndx = -1; //-1 so when we increment below, the first index is 0
    String text[] = new String[1000]; //To be safe, declare more than we
        while(sf.hasNext( ))
        {
            maxIndx++;
            text[maxIndx] = sf.nextLine( ); 
            //System.out.println(text[maxIndx]); //Remove rem for testing
        }
        sf.close();

        for(int j =0; j <= maxIndx; j++)
        {
            Scanner sc = new Scanner(text[j]);
        }
        String answer = ""; //We will accumulate the answer string here. 
        int sum; //accumulates sum of integers
        for(int j = 0; j <= maxIndx; j++)
        {
            Scanner sc = new Scanner(text[j]);
            sum = 0;
            answer = ""; 
            while(sc.hasNext())
            {
                int i = sc.nextInt();
                answer = answer + i + " + ";
                sum = sum + i; 
            }
            //sc.next();
            answer = answer + " = " + sum; 
            System.out.println(answer);
        } 
    }
}

输出是

12 + 10 + 3 + 5 +  = 30
18 + 1 + 5 + 92 + 6 + 8 +  = 130
2 + 9 + 3 + 22 + 4 + 11 + 7 +  = 58

最后一个数字后面多了一个，我该如何解决？

Answer 1

在最后一次迭代后，您将获得一个“额外”加号，因为这是您打印它的方式。您将以 + 结束 String，因为它可以在您的 while 循环中看到。

要更改它，请在值前添加 + as

if(sc.hasNext()) {
   int i = sc.nextInt();
   answer = i + "";
   sum += i;
   while(sc.hasNext())
      {
          i = sc.nextInt();
          answer = answer + " + " + i;
          sum = sum + i; 
      }
}

或者，如果您使用 Java 8，则可以将 StringJoiner 用作

StringJoiner joiner = new StringJoiner(" + ");
while(sc.hasNext())
{
    i = sc.nextInt();
    // This automaticly includes a " + " between the values.
    joiner.add(String.valueOf(i));
    sum = sum + i; 
}