Quick String / char question

Question

Hi, i have to write a encrytion method for a assignment, it must take a string, move the characters on by a set number given by the user and return the result.
public class Encryption
    int key;
    public Encryption(int k)
        key = k;
public String encrypt(String si)
si = si.toUpperCase();
int i = 0;
for (int index = 0; index< si.length(); index++);
char c = si.charAt(i);
int n = c - 'A' + key;
char a = (char)(n + 'A');
return si ;
}it compiles, but what i need to know is how to i get my new chars (that have been moved the set amout) back into a string that is returned to the user, as i cant seem to find the code i need to do this???

Answer 1

String result = "";
Each time through the loop, you will want to add it to the result
result = result + a;This is poor adviceimport java.io.*;
public class Encryption{
   public static void main(String[] args) {
      new Encryption();
   Encryption(){
      String toEncyrpt = "The quick brown fox jumps over the lazy dog";
      int key = 0;
      try{
         BufferedReader br= new BufferedReader(new InputStreamReader(System.in));
         System.out.print("Enter a number for the encryption key ");
         key = Integer.parseInt(br.readLine());
      }catch(IOException e){}
      String encrypted = encrypt(toEncyrpt, key);
      System.out.println("Encrypted string : "+ encrypted);
      String decrypted = decrypt(encrypted, key);
      System.out.println("Decrypted string : "+ decrypted);
    public String encrypt(String s, int k){
       StringBuffer sb = new StringBuffer();
       for(int i=0; i<s.length(); i++) {
           int temp = (int) s.charAt(i)+k;
           sb.append((char)temp);
       return sb.toString();
    public String decrypt(String s, int k){
       StringBuffer sb = new StringBuffer();
       for(int i=0; i<s.length(); i++) {
           int temp = (int) s.charAt(i)-k;
           sb.append((char)temp);
       return sb.toString();
}