Read binary file backwards

Question

What I need to do is read in a file backwards. What I would like to be able to do is read the file backwards then as is moves backwards see if the value = G or in hex 47 then see if the next value = N or in hex 4E and then see if the next value = P. I'm currently using the binary IO to read in and then using...

Here is a link to an image which will better show what I mean.. http://www.facebook.com/photo.php?pid=2189508&l=92393dfccb&id=1283154964

  String s = Integer.toHexString(hexIn);
  if(s.length() < 2){
   s = "0" + Integer.toHexString(hexIn);
  }

To make sure the hex does not miss any zeros on the end (which I found on this site::)

Answer 1

As you can imagine, reading backwards isn't the normal thing, and you'll have to do something weird.

But you can place the index into the file yourself. If you did that, placed it at the end, read a byte, then placed it at (end-1), read a byte, and so on, you'd succeed.

It would be horribly slow, so what you do iss read as much as you can into a buffer, starting at the end, then go through the buffer backward, then refill the buffer.

This tutorial tells you all about random access I/O in Java.

Answer 2

RandomAccessFile would be the easiest class to use to read a file backwards.

Answer 3

Rather than read the file in backwards and look for your string, why don't you just reverse your string and look for it in the file going forwards? That would seem to be an easier solution?