有没有一种实用的方法可以从文件中读取前n行? [英] Is there a utility method for reading first n lines from file?

问题描述

我搜索了以下热门图书馆:

I have searched the following popular libraries:

• 番石榴- Fiels.readLines
• nio - Files.readFirstLine 或 Files.readAllLines
• ApacheCommons - FileUtils.readLines

• Guava - Fiels.readLines
• nio - Files.readFirstLine or Files.readAllLines
• ApacheCommons - FileUtils.readLines

所有方法都将整个文件作为String集合读取到内存中.但这对具有数千行的大型文件没有用吗?是否有一个简单的方法调用来读取其中任何一个库中文件的前 n 行?

All methods read whole file into memory as String collection. But that is not useful for large files with thousands of lines? Is there a simple method call to read the first n lines of a file in any of these libraries?

推荐答案

您可以使用

You could use LineNumberReader

LineNumberReader reader = 
    new LineNumberReader
      (new InputStreamReader(new FileInputStream("/path/to/file"), "UTF-8"));

try{
  String line;
  while (((line = reader.readLine()) != null) && reader.getLineNumber() <= 10) {
     ...
   }
}finally{
   reader.close()
}

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