Number of lines in a file in Java

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抹茶落季
抹茶落季 2020-11-22 05:31

I use huge data files, sometimes I only need to know the number of lines in these files, usually I open them up and read them line by line until I reach the end of the file<

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  •  予麋鹿
    予麋鹿 (楼主)
    2020-11-22 05:50

    The answer with the method count() above gave me line miscounts if a file didn't have a newline at the end of the file - it failed to count the last line in the file.

    This method works better for me:

    public int countLines(String filename) throws IOException {
        LineNumberReader reader  = new LineNumberReader(new FileReader(filename));
    int cnt = 0;
    String lineRead = "";
    while ((lineRead = reader.readLine()) != null) {}
    
    cnt = reader.getLineNumber(); 
    reader.close();
    return cnt;
    }
    

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