Question

Exception in thread "main" java.util.NoSuchElementException: No line found
    at java.util.Scanner.nextLine(Unknown Source)
    at LineIO.main(LineIO.java:39)

没有红线。我会发布代码......

import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.Scanner;
    public class LineIO {

    public static void main(String[] args)throws FileNotFoundException{
        Scanner console = new Scanner(System.in);
        System.out.print("Enter Input file name: ");
        String inputFileName = console.next();
        System.out.print("Output file: ");
        String outputFileName = console.next();
                File inputFile = new File(inputFileName);
                Scanner in = new Scanner(inputFile);
                PrintWriter out = new PrintWriter(outputFileName);
                int lineNumber = 1;
                int lineNumber2 = 10;
                int lineNumber3 = 20;
                int lineNumber4 = 30;
                int lineNumber5 = 40;



                System.out.println("Enter name 5 names:");
                String person1 = console.next();
                String person2 = console.next();
                String person3 = console.next();
                String person4 = console.next();
                String person5 = console.next();

                double sum = 0;
                int j = 0;
               while (j < 10)
                {
                  String line = in.nextLine();
                 int num = Integer.parseInt(line);
                  sum = sum+num;
                }
               double average = sum / 10;

            System.out.println(person1 + " average score is " + average);
            System.out.println(person2 + " average score is " + lineNumber2);
            System.out.println(person3 + " average score is " + lineNumber3);
            System.out.println(person4 + " average score is " + lineNumber4);
            System.out.println(person5 + " average score is " + lineNumber5);

                in.close();
                out.close();
    }
}

为什么我会继续收到此错误？我无法理解错误消息，也不明白为什么代码没有实现。我设置了input.txt和output.txt文件......

Answer 1

快速搜索了这篇文章：java.util.NoSuchElementException: No line found

文件中没有足够的行。

除了确保文件中有足够的行外，还要添加下一行的检查以避免此错误：

            while (j < 10)
            {
              if (in.hasNextLine()){
               String line = in.nextLine();
               int num = Integer.parseInt(line);
               sum += num; //minor change here
              }
              else{
                 System.out.println("Not enough lines!");
                 break;
              }
              j++; //increment j
            }

Eclipse中此错误的含义

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