Question

I am reading a file via the BufferedReader

String filename = ...
br = new BufferedReader( new FileInputStream(filename));
while (true) {
   String s = br.readLine();
   if (s == null) break;
   ...
}

I need to know if the lines are separated by ‘\n’ or ‘\r\n’
is there way I can find out ?

I don’t want to open the FileInputStream so to scan it initially.
Ideally I would like to ask the BufferedReader since it must know.

I am happy to override the BufferedReader to hack it but I really don’t want to open the filestream twice.

Thanks,

Note: the current line separator (returned by System.getProperty(“line.separator”) ) can not be used as the file could have been written by another app on another operating system.

Answer 1

After reading the java docs (I confess to being a pythonista), it seems that there isn’t a clean way to determine the line-end encoding used in a specific file.

The best thing I can recommended is that you use BufferedReader.read() and iterate over every character in the file. Something like this:

String filename = ...
br = new BufferedReader( new FileInputStream(filename));
while (true) {
   String l = "";
   Char c = " ";
   while (true){
        c = br.read();
        if not c == "\n"{
            // do stuff, not sure what you want with the endl encoding
            // break to return endl-free line
        }
        if not c == "\r"{
            // do stuff, not sure what you want with the endl encoding
            // break to return endl-free line
            Char ctwo = ' '
            ctwo = br.read();
            if ctwo == "\n"{
                // do extra stuff since you know that you've got a \r\n
            }
        }
        else{
            l = l + c;
        }
   if (l == null) break;
   ...
   l = "";
}