我正在尝试在循环内使用scanner.nextLine(),但出现异常。
问题位于代码的这一部分。

        while(!sentence.equals("quit")){
        dealWithSentence(sentence, voc);
        System.out.println("Enter your sentence:");
        sentence = scanner.nextLine();
    }


有一个例外:


  线程“主”中的异常java.util.NoSuchElementException:找不到行
      在java.util.Scanner.nextLine(未知来源)
      位于il.ac.tau.cs.sw1.ex4.SpellingCorrector.main(SpellingCorrector.java:34)


那是我完整的方法代码:

    public static void main(String[] args) throws Exception{
    Scanner scanner = new Scanner(System.in);
    String filePath = scanner.nextLine();
    if (filePath.contains(" ")){
        scanner.close();
        throw new Exception("[ERROR] the file path isnt correct");
    }

    File file = new File(filePath);
    String[] voc = scanVocabulary(new Scanner(file));
    if (voc == null)
    {
        scanner.close();
        throw new Exception("[ERROR] the file isnt working");

    }


    System.out.println("Read " + voc.length + " words from " + file.getName());

    System.out.println("Enter your sentence:");

    String sentence = scanner.nextLine();

    while(!sentence.equals("quit")){
        dealWithSentence(sentence, voc);
        System.out.println("Enter your sentence:");
        sentence = scanner.nextLine();
    }
    scanner.close();

最佳答案

Scanner.nextLine()的工作方式如下。

   String s = "Hello World! \n 3 + 3.0 = 6.0 true ";

   // create a new scanner with the specified String Object
   Scanner scanner = new Scanner(s);

   // print the next line
   System.out.println("" + scanner.nextLine());

   // print the next line again
   System.out.println("" + scanner.nextLine());

   // close the scanner
   scanner.close();
   }


这将为您提供以下输出

Hello World!
3 + 3.0 = 6.0 true


因此,基本上,它开始扫描并跳过直到第一个新行字符,然后返回到目前为止已跳过的内容。在您的情况下,如果您只有一个句子而根本没有换行(\ n),它将跳过整个长度,并且永远找不到新行。从而抛出异常...在句子中间添加新的换行符,看看异常是否消失

学分至:http://www.tutorialspoint.com/java/util/scanner_nextline.htm

07-24 09:50
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