Java - 通过字符读取文本文件的最快方法 [英] Java - Fastest Way to Reading Text Files Char by Char

问题描述

我有近500个1000万字的文本文件。我必须索引这些单词。什么是从一个文本文件逐字符读取最快的方式？这是我最初的尝试：

$ p $ InputStream ist = new FileInputStream（this.path +/+ doc）;
BufferedReader in = new BufferedReader（new InputStreamReader（ist））;

字符串行; （（line = in.readLine（））！= null）{


$ line = to line.toUpperCase（Locale.english）;
String word =; （int j = 0; j <= line.length（）; j ++）{
char c = line.charAt（j）;


// OPERATIONS

}


解决方案

阅读更多：的比较（＃）（＃）（＃）（＃）/ /

现在回到原来的问题：

输入字符串：你好吗？

所以你需要索引该行的字，即：

  BufferedReader r = new BufferedReader（new InputStreamReader（inputStream））; 
字符串行; （（line = r.readLine（））！= null）{
 String [] splitString = line.split（\\s +）; 
 //在这里做数组的东西，即构造索引。 
 
  

注意： \\s + 会将字符串中的分隔符作为标签，空格等任何空白字符。

I have nearly 500 text files with 10 million words. I have to index those words. What is the fastest way to read from a text file character by character? Here is my initial attempt:

InputStream ist = new FileInputStream(this.path+"/"+doc);
BufferedReader in = new BufferedReader(new InputStreamReader(ist));

String line;

while((line = in.readLine()) != null){


   line = line.toUpperCase(Locale.ENGLISH);
    String word = "";

    for (int j = 0; j <= line.length(); j++) {
         char  c= line.charAt(j);
     // OPERATIONS

}

解决方案

read() will not give considerable difference in performance.

Read more: Peter Lawery's comparison of read() and readLine()

Now, coming back to your original question:
Input string: hello how are you?
So you need to index the words of the line, i.e.:

BufferedReader r = new BufferedReader(new InputStreamReader(inputStream));
String line;
while ((line = r.readLine()) != null) {
   String[] splitString = line.split("\\s+");
   //Do stuff with the array here, i.e. construct the index.
}

Note: The pattern \\s+ will put delimiter in the string as any whitespace like tab, space etc.

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