Java 读取行空白

发布于 2025-01-04 09:19:44 字数 733 浏览 5 评论 0原文

FileInputStream fstream = new FileInputStream("data.txt");

// Get the object of DataInputStream
DataInputStream in = new DataInputStream(fstream);

BufferedReader br = new BufferedReader(new InputStreamReader(in));

String strLine;
//Read File Line By Line

while ((strLine = br.readLine()) != null) 
  {
    //Test if it is a line we need
    if(strLine.charAt(0) != ' ' && strLine.charAt(5) == ' '
       && strLine.charAt(10) == ' ' && strLine.charAt(15) == ' '
       && strLine.charAt(20) == ' ' && strLine.charAt(25) == ' ' )
      {
        System.out.println (strLine);
      }
  }

我正在读取带有空格行（不仅仅是空格）的文件，并比较某些索引处的字符以查看是否需要该行，但是当我读取一行空格时，我得到的字符串索引超出范围。

原文

FileInputStream fstream = new FileInputStream("data.txt");

// Get the object of DataInputStream
DataInputStream in = new DataInputStream(fstream);

BufferedReader br = new BufferedReader(new InputStreamReader(in));

String strLine;
//Read File Line By Line

while ((strLine = br.readLine()) != null) 
  {
    //Test if it is a line we need
    if(strLine.charAt(0) != ' ' && strLine.charAt(5) == ' '
       && strLine.charAt(10) == ' ' && strLine.charAt(15) == ' '
       && strLine.charAt(20) == ' ' && strLine.charAt(25) == ' ' )
      {
        System.out.println (strLine);
      }
  }

I am reading in a file with lines of whitespace(not only whitespace) and comparing chars at certain indexes to see if I need the line however when I read in a line of whitespace I get a string index out of range.

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没有你我更好 2025-01-11 09:19:44

例如，如果该行的长度为 0 并且您试图确定位置 10 处的字符，您将得到一个异常。只需在处理之前检查该行是否不全是空格。

if (line != null && line.trim().length() > 0)
{
   //process this line
}

If the line is length 0 and you are trying to determine the character at location 10 for example you are going to get an exception. Just put in a check to see if the line is not all whitespace before processing it.

if (line != null && line.trim().length() > 0)
{
   //process this line
}

回复收藏 0 原文

平定天下 2025-01-11 09:19:44

空行不会为 null，而是空字符串 ''。如果您尝试读取索引 0 处的字符，它将中断。

 while ((strLine = br.readLine()) != null) 
 {
    //remove whitespace infront and after contents of line.
    strLine = strLine.trim();

    if (strLine.equals(""))
      continue;

     //check that string has at least 25 characters when trimmed.
    if (strLine.length() <25)  
       continue;

    //Test if it is a line we need
    if(strLine.charAt(0) != ' ' && strLine.charAt(5) == ' ' && strLine.charAt(10) == ' ' && strLine.charAt(15) == ' ' && strLine.charAt(20) == ' ' && strLine.charAt(25) == ' ' )
    {
         System.out.println (strLine);
    }
 }

您还可以尝试使用 Java Scanner 类。它对于读取文件确实很有用。

An empty line will not be null, but and empty string ''. It will break if you try and read the character at index 0.

 while ((strLine = br.readLine()) != null) 
 {
    //remove whitespace infront and after contents of line.
    strLine = strLine.trim();

    if (strLine.equals(""))
      continue;

     //check that string has at least 25 characters when trimmed.
    if (strLine.length() <25)  
       continue;

    //Test if it is a line we need
    if(strLine.charAt(0) != ' ' && strLine.charAt(5) == ' ' && strLine.charAt(10) == ' ' && strLine.charAt(15) == ' ' && strLine.charAt(20) == ' ' && strLine.charAt(25) == ' ' )
    {
         System.out.println (strLine);
    }
 }

You can also try and use the Java Scanner class. It is really useful for reading in files.

回复收藏 0 原文

樱花落人离去 2025-01-11 09:19:44

您在这里所做的是使用 strLine.charAt(25) 检查章程直到第 25 个字符，而您的 String strLine 可能没有那么多字符。如果 index 参数不小于该字符串的长度，则 charAt(int index) 方法将抛出 IndexOutOfBoundsException。

您可以通过调用 strLine.length() 找到 strLine 的长度，然后检查 0 中的 charAt() > 到 strLine.length() - 1 并且您不会看到该异常。