CIS 3020 Project 5

Code

Cipher.java

import java.lang.String;

public class Cipher {

 //output string that holds encrypted message
 private String output = new String();
 //replacement letter for encryption (changes often!)
 private String replacement = new String();
 //how to know when to stop trying to replace letters
 private int keyLen = 0;

 private void clearOutput(){
   //clear this.output
   this.output = "";
 }
  
 public String getOutput(){
   //return output
   return(this.output);
 }

 public String encipher (String encode, String key, String message){
   //reset this.output
   clearOutput();
   //determine key length
   this.keyLen = (key.length()-1);
   //return the encoded message
   return(encode(encode, key, message));
 }

 private String encode(String encode, String key, String message) {
   //is there anything left to encode?
   if (message.length() != 0) {
    // Get the first character in the initiator string.
     //the following two lines (3 lines if you really want to,
     //but letterReplacement would have to return this.replacement)
     //could have been combined but weren't for clarity.
     String letter = message.substring(0, 1);
     //replace letter with encrypted letter
     letterReplacement(letter, encode, key, 0);
       //concatenate output with encoded letter     
       this.output = this.output.concat(this.replacement);
       //repeat for next letter
       encode(encode, key, message.substring(1));
    } //end if
  //end big if (length != 0)
   return (this.output);
 }//end next generation

private void letterReplacement(String letter, String encode, String key, int n){

 //don't go out of bounds!
 if (n<=this.keyLen){
   //try to replace letter with encoded character
   this.replacement = letter.replace(encode.charAt(n),key.charAt(n));
   //did replacement succeed?
   if (this.replacement.equals(letter)){
     //if not, try again
     letterReplacement(letter, encode, key, n+1);
   }
 }

} }