java - Define a method named encode that accepts a String as input and returns a new String which is the original String encoded using the ROT13 cipher -

for example: string "abc" should return "nop".

i did system.out.println , printing correct result, however, junit test case giving me red bar. method move13 takes character , moves 13 spaces left or right.

the method encode having trouble with.

package code;  public class encoder {      public char move13(char letter) {         if (letter >= 'a' && letter <= 'm') {             return (char)(letter + 13);         }         if (letter >= 'a' && letter <= 'm') {             return (char)(letter + 13);         }         if (letter >= 'n' && letter <= 'z') {             return (char)(letter - 13);         }         if (letter >= 'n' && letter <= 'z') {             return (char)(letter - 13);         }         return letter;     }      public string encode(string text) {         string valueofchar = "";         (int = 0; < text.length(); i++) {             char character = text.charat(i);             character = move13(character);             valueofchar = string.valueof(character);             system.out.println(valueofchar);          }         return valueofchar;      } } 

here go, hope helps

public static char move13(char letter) {     if (letter >= 'a' && letter <= 'm')         return (char) (letter + 13);     if (letter >= 'a' && letter <= 'm')         return (char) (letter + 13);     if (letter >= 'n' && letter <= 'z')         return (char) (letter - 13);     if (letter >= 'n' && letter <= 'z')         return (char) (letter - 13);     return letter; }  public static string encode(string text) {     stringbuilder sb = new stringbuilder();     (int = 0; < text.length(); i++) {         char character = text.charat(i);         character = move13(character);         sb.append(character);         //system.out.println(valueofchar);      }     return sb.tostring();  } 

the char concatenated in stringbuilder (sb.append(char)). after each letter processed in move13(), return concatenated chars (sb.tostring()).