Reverses.java

package reverseread;

import java.io.*;
import java.util.ArrayList;
import java.util.regex.Pattern;

/**
 * Created by gava9 on 07/02/2017.
 */
public class ReverseRead {

    public static void main(String[] args) {
        String home = System.getProperty("user.home");
        BufferedReader br;
        File in = new File(home + "\\sample.txt");
        File out = new File(home + "\\output.txt");
        ArrayList<String> lines = new ArrayList<>();

        // Lee el archivo y agrega sus lineas a un arraylist
        try {
            br = new BufferedReader(new FileReader(in));
            String line;
            while((line = br.readLine()) != null) {
                lines.add(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

        BufferedWriter bw;
        String tokens[] = null;
        String splitPattern = "";
        Pattern p = Pattern.compile(splitPattern);
        ArrayList <String> reverses = new ArrayList<>();

        for (String l: lines) {
            String l1 = l;
            tokens = p.split(l);
            for (int i = tokens.length - 1; i >= 0; i--) {
                l+=tokens[i];
            }
            reverses.add(l1 + "\t"  + l);
        }

        try {
            if(!out.exists()) {
                out.createNewFile();
            }

            bw = new BufferedWriter(new FileWriter(out));

            for (String op : reverses) {
                bw.write(op);
                bw.newLine();
                bw.newLine();
            }
            bw.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}