从文本文件中读出单词和数字

Question

我正在编写一个程序，该程序读取文本文件并向ArrayList添加唯一的单词和数字。我为此使用了分隔符，但在运行程序时出现NoSuchElementException。我的分隔符是错的还是我犯了另一个错误？

这里是我的程序：

import java.util.*; 
import java.io.*; 
public class Indexer 
{ 
    public static void main(String[] args) throws FileNotFoundException 
    { 

     Scanner fileScanner = new Scanner(new File("File.txt")).useDelimiter("[.,:;()?!\" \t]+~\\s"); 
     int totalWordCount = 0; 
     ArrayList<String> words = new ArrayList<String>(); 
     while ((fileScanner.hasNext()) && (!words.contains(fileScanner.next()))) 
     { 
     words.add(fileScanner.next()); 
     totalWordCount++; 
     } 
     System.out.println("There are " + totalWordCount + " unique word(s)"); 
     System.out.println("These words are:"); 
     System.out.println(words.toString()); 
     fileScanner.close(); 
    } 
}  

Answer 1

这应该工作，你可以使用的toString或迭代器来显示的话：

Set<String> words = new HashSet<String>(); 
     while ((fileScanner.hasNext())) { 
       words.add(fileScanner.next()); 
     } 
     System.out.println("There are " + words.size() + " unique word(s)"); 
     System.out.println("These words are:"); 
     //System.out.println(words.toString()); 
     for (Iterator<String> it = words.iterator(); it.hasNext();) { 
      String f = it.next(); 
      System.out.println(f); 
     } 
     fileScanner.close(); 

Answer 2

我会用设置的不是List

Set<String> words = new HashSet<String>(); 
while (fileScanner.hasNext()) { 
     words.add(fileScanner.next()); 

Answer 3

这很可能是NoSuchElementException来自while循环中的第二个fileScanner.next（）。

当到达文件的最后一个元素时，它将在while循环条件中从fileScanner.next（）中读取，导致在循环内部执行第二个fileScanner调用时没有剩余元素。

一种解决方案可能是调用fileScanner.next（）每一次迭代：

Scanner fileScanner = new Scanner(new File("File.txt")).useDelimiter("[.,:;()?!\" \t]+~\\s"); 
    int totalWordCount = 0; 
    Set<String> words = new HashSet<String>(); 
    String nextWord; 
    while ((fileScanner.hasNext()) && (!words.contains(nextWord = fileScanner.next()))) 
    { 
    words.add(nextWord); 
    totalWordCount++; 
    } 
    System.out.println("There are " + totalWordCount + " unique word(s)"); 
    System.out.println("These words are:"); 
    System.out.println(words.toString()); 
    fileScanner.close(); 
}