Ive been given this code as part of a lexical analyser for which i will be coding a syntax analyser - however the file the lexical analyser will be reading will come throught this code:

public static void main(String[] args) throws IOException
{
BufferedReader din = new BufferedReader(new InputStreamReader(System.in)) ;
System.err.print("file? ") ;
System.err.flush() ;
String fileName = din.readLine().trim() ;
LexicalAnalyser lex = new LexicalAnalyser(fileName) ;
} // end of class LexicalAnalyser

The thing is - where is the path name meant to go? It works by replacing fileName however im not so sure why my lecturer has coded the bufferedreader and inputstreamreader

You type in the filename and path from the console when you run th code. Isn't that what System.in is? I don't know I've never used it.

yup. What I find rather troublesome is that he uses System.err for non-error output...
It would be much preferred to read the inputfile through the commandline.