Major Description
I needed to analyse a log file today and I was looking for a ReversedLinesFileReader: A class that behaves exactly like BufferedReader except that it goes from bottom to top when readLine() is called. I didn't find it in IOUtils and the internet didn't help a lot either, e.g. http://www.java2s.com/Tutorial/Java/0180__File/ReversingaFile.htm is a fairly inefficient - the log files I'm analysing are huge and it is not a good idea to load the whole content in the memory.
So I ended up writing an implementation myself using little memory and the class RandomAccessFile - see attached file. It's used as follows:
int blockSize = 4096; // only that much memory is needed, no matter how big the file is
ReversedLinesFileReader reversedLinesFileReader = new ReversedLinesFileReader (myFile, blockSize, "UTF-8"); // encoding is supported
String line = null;
while((line=reversedLinesFileReader.readLine())!=null) {
... // use the line
if(enoughLinesSeen)
}
reversedLinesFileReader.close();
I believe this could be useful for other people as well!