Question

当我运行我的代码时，输出是这样的：

4 went down to the market
0   where she bought herself
1 
0 kitten
0  she thought the 
6 was
0     precious,
2 she
0  named the kitten
String index out of range: -1

但是期望的输出应该是这样的：

0 Lisa went down to the market
3 where she bought herself
0 a 
1 kitten
2 she thought the 
0 kitten was
5 precious,
0 so she
2 named the kitten
0 Princess

我收到了一个包含文本行的文本文件http://pastebin.com/h51eh8EX。我必须编写一个读取文本的类，计算每行开头的空格数，然后写入行以删除每行开头的空格，并用存在的空白数替换它们。 / p>

你能解释一下我的问题吗？

以下是代码：

import java.io.File;
import java.io.IOException;
import java.util.Scanner;

public class Squeeze {
    String fname;//name of the file that contains text to be squeezed

    /**
     * Constructor to initialize fname
     * @param name - name of the file to be squeezed
     */
    public Squeeze(String name)
    {
            //TODO Your code goes here
            fname = name;
    }
    /**
     * Method to remove and count any extra
     * leading spaces
     *
     */
    public void squeezeText()
    {
            //TODO Your code goes here
            try
    {
        File file = new File("squeeze.txt");
       Scanner in = new Scanner(file);
        while (in.hasNext())
        {

            String line = in.nextLine();  
            int count = line.substring(0, line.indexOf(" ")).length();
            line = count + line.substring(line.indexOf(" "));
            System.out.println(line);
        }
        in.close();
    }
    catch(Exception e)
    {
        System.out.println( "Error: " + e.getMessage());
    }

    }
}

Answer 1

使用indexOf（）对此不准确，因为它只会让您第一次出现空格字符。

Java String API：http://docs.oracle.com/javase/6/docs/api/java/lang/String.html

Answer 2

您的计数方法已关闭，最简单的方法就是循环遍历字符。这是你可以做到的一种方式 -

while (in.hasNext()) {
  String line = in.nextLine();
  int count = 0;
  for (char c : line.toCharArray()) {
    if (c == ' ') {
      count++;
    }
  }
  line = count + " " + line;
  System.out.println(line);
}

Answer 3

尝试使用正则表达式

 while (in.hasNext())
 {
    String line = in.nextLine();    
    Pattern p = Pattern.compile("^\\s+\\w");
    Matcher m = p.matcher(line);
    if (m.find()) {
            System.out.println(m.group().length() - 1 + " " + line);
    } else {
            System.out.println("0" + " " + line);
    }
}

写/读文件和例外

3 个答案: