Question

我刚刚创建了一个程序，它应该扫描文件并计算行数，元音数和其他许多东西，但是当我运行它时，它会进入一个无限循环。我很确定它与我不熟悉的.hasNext()和.hasNextLine()方法有关

import java.util.*;
import java.io.*;
/**
 *
 *
 */
public class Wordcount1 {


    public static void main(String[] args) {
        int vowels=0;
        int punctuation=0;
        int sentences=0;
        int words=0;
        int lines=0;
        int alphaNumeric=0;

       try{
       Scanner input = new Scanner(System.in);
       System.out.println("Enter file name: ");

       File file = new File(input.nextLine());
       Scanner fileReader = new Scanner(file);

       while(fileReader.hasNextLine()){
           lines +=1;
       }
       while(fileReader.hasNext()){
           { fileReader.next();
           words +=1;
           }
           String word = fileReader.next();
           for (int i=0; i<word.length();i++){
               char ch= word.charAt(i);
               if(ch=='a'||ch=='e'||ch=='i'||ch=='o'||ch=='u')
                   vowels +=1;
               if((ch=='!'||ch=='.'||ch=='?'))
                   sentences +=1;
               if(Character.isLetterOrDigit(ch))
                   alphaNumeric +=1;
               switch(ch){
                   case ',':
                    punctuation +=1;
                    break;
                   case '[':
                    punctuation +=1;
                    break;
                   case ']':
                    punctuation +=1;
                    break;
                   case ':':
                    punctuation +=1;
                    break;
                   case '`':
                    punctuation +=1;
                    break;
                   case '-':
                    punctuation +=1;
                    break;
                   case '!':
                    punctuation +=1;
                    break;
                   case '_': 
                    punctuation +=1;
                    break;
                   case '(':
                    punctuation +=1;
                    break;
                   case ')':
                    punctuation +=1;
                    break;
                   case '.':
                    punctuation +=1;
                    break;
                   case '?':
                    punctuation +=1;
                    break;
                   case '"':
                    punctuation +=1;
                    break;
                   case ';':
                    punctuation +=1;
                    break;

               }

           }
       }
        System.out.println("The number of words in the file name: " + words);
        System.out.println("The number of lines in the file name: " + lines);
        System.out.println("The number of alphanumeric characters: "
                + "in the file name: " + alphaNumeric);
        System.out.println("The number of sentences in the file name: "
                + sentences);
        System.out.println("The number of vowels in the file name: " + vowels);
        System.out.println("The number of punctuations in the file name: " 
                + punctuation);

       }catch(FileNotFoundException e){
           e.printStackTrace();
       }
    }
}

Answer 1

while(fileReader.hasNextLine()){
    lines +=1;
}

在这里，你反复询问文件“你还有更多行”，但实际上并没有消耗任何行。所以，它一直回答“是的，我有更多的行”。

Answer 2

因为您没有在fileReader上调用next()方法

调用Scanner.hasNext()仅表示是否有令牌，但不会使扫描程序前进：

为什么我会得到一个无限循环

2 个答案: