Read a file in reverse order line by line without much overhead

Question

I need read i file in reverse order, because now it must run all file to find something that I know it`ll be in the last lines. My objective is to make my application Faster Which is the FASTEST way to read a file line by line in reverse order?

For example: My file is

  line1
  line2
  line3
  line4
  line5

I want to read

  line5
  line4
  line3
  line2
  line1

I know there`s a lot of ways to do it... but which one will give me less overhead?

Answer 1

Try this out, I think this is the fastest way to read a file in reverse order.

import java.io.*;  
import java.util.*;  
class FileReaderReverse  
{  
    public static void main(String[] args) throws IOException,FileNotFoundException  
    {  
        FileReader fr=new FileReader("abc.txt");  
        BufferedReader br=new BufferedReader(fr);  
        String s;  

        List<String> tmp = new ArrayList<String>();  
        do
        {  
            s = br.readLine();  
            tmp.add(s);  
        }while(s!=null);  


        for(int i=tmp.size()-1;i>=0;i--) {  
            System.out.println(tmp.get(i));  
        }  
    }  
}