Caesar Cipher

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;



public class Main {

    public static void main(String[] args)
    {


        ArrayList<String> msg=readFromFile("plaintext.txt");
        writeToFile(msg,"cipherText.txt");
        ArrayList<String> normalText=readFromFile("cipherText.txt");
        writeToFile(normalText,"plaintext2.txt");

    }
    public static ArrayList<String> readFromFile(String path)
    {
        BufferedReader br = null;
        //ArrayList[] msg = null;
        ArrayList<String> msg = new ArrayList<String>();

        try {

            String sCurrentLine;

            br = new BufferedReader(new FileReader(path));
            int i=0;
            while ((sCurrentLine = br.readLine()) != null)
            {
                if(path=="plaintext.txt")
                {
                String result=encode(sCurrentLine,3);
                msg.add(result);
                }
                else
                {
                    String originalLine=decode(sCurrentLine);
                    msg.add(originalLine);

                }

            }

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (br != null)br.close();
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return msg;

    }
    public static void writeToFile(ArrayList<String> msg,String path)
    {
        try {


            File file = new File(path);

            // if file doesnt exists, then create it
            if (!file.exists()) {
                file.createNewFile();
            }

            FileWriter fw = new FileWriter(file.getAbsoluteFile());
            BufferedWriter bw = new BufferedWriter(fw);
            Iterator<String> iterator = msg.iterator();
            while (iterator.hasNext())
            {
                //System.out.println(iterator.next());
                bw.write(iterator.next());
                bw.newLine();
            }
            bw.close();

            System.out.println("Done");

        } catch (IOException e) {
            e.printStackTrace();
        }

    }

public static String encode(String line,int key)
{
    char[] lineChar=line.toCharArray();
    int offset=key%26+26;
    StringBuilder secretMessage=new StringBuilder();
    for(int i=0;i<lineChar.length;i++)
    {
        if(lineChar[i]==' ')
        {
            secretMessage.append(lineChar[i]);
            continue;
        }
        else
        {
            secretMessage.append((char) ('A' + (lineChar[i] - 'A' + offset) % 26 ));


        }
    }
    return secretMessage.toString();
}
public static  String decode(String line)
{
    return encode(line,23);
}
}