Output accumulates each iteration instead of resetting

Question

The code runs properly the first time then run it again using the while loop and lets say the first time I entered AA and it becomes CC then it runs again I enter AA again it will come out with CCCC do it again it comes out with CCCCCC I don't want that I need it to not keep the data from the string each time it loops.

import java.util.*;
public class SecretCypher {

    public static void main(String args[]) {

        Scanner kb = new Scanner(System.in);
        StringBuffer e = new StringBuffer();
        System.out.println("Welcome to Secret Cypher!");

            char loop = 'Y';
            while(loop == 'Y' || loop == 'y') {
                System.out.println("");
                System.out.println("Enter your cypher in upper case.");
                String s = kb.nextLine();


                char[] cs = s.toCharArray();
                for (int i = 0; i < cs.length; i++) {
                    e.append((char)('A' + (cs[i] - 'A' + 2) % 26));
                }
                if(s == s.toLowerCase()) {
                    System.out.println("Remember to use upper case letters!");
                    System.exit(0);//Also I was bored of using break and this works any where in the code.
                }
                System.out.println(e.toString());


                System.out.println("Do you want to enter another cypher? > ");
                String again = kb.nextLine();
                if(again.charAt(0) == 'N') {
                    System.out.println("Hope you come back again!");
                    break;
                }
            }
    }
}

Answer 1

You're reusing the same string buffer. If you keep putting things into the same buffer without clearing it, you're obviously going to get extraneous stuff from previous iterations.

Simply declare the StringBuffer inside the while loop so that it is created on each iteration.

Anyway, you should learn to use your debugger, instead of asking here for us to debug. If anything, using the debugger can offer extremely valuable insight into the troubles that you are having here.