ROT13

Crypto/src/CaesarCipher.java

@@ -0,0 +1,9 @@
+package src;
+
+public class CaesarCipher extends ROT13 {
+
+    CaesarCipher(Character cs, Character cf) {
+        super(cs, cf);
+    }
+
+}

Crypto/src/ROT13.java

@@ -2,7 +2,7 @@ import static java.lang.Character.isLowerCase;
 import static java.lang.Character.isUpperCase;
 import static java.lang.Character.toLowerCase;
 
-public class ROT13  {
+public class ROT13 {
 
     ROT13(Character cs, Character cf) {
     }
@@ -12,21 +12,42 @@ public class ROT13  {
 
 
     public String crypt(String text) throws UnsupportedOperationException {
-
-        return "";
+        /**Split alphabet in half. Add 13 to chars before middle of alphabet. Subtracting 13 will rotate
+         to the begining of the alphabet. ASCII chars are in order so adding to ascii value will get next
+         alphabet*/
+        StringBuilder shiftStr = new StringBuilder();
+        for (int i = 0; i < text.length(); i++) {
+            char charToShift = text.charAt(i);
+            if (charToShift >= 'a' && charToShift <= 'm') {
+                charToShift += 13;
+            } else if (charToShift >= 'A' && charToShift <= 'M') {
+                charToShift += 13;
+            } else if (charToShift >= 'n' && charToShift <= 'z') {
+                charShift -= 13;
+            } else if (charToShift >= 'N' && charToShift <= 'Z') {
+                charToShift -= 13;
+            }
+        }
+        shiftStr.append(charToShift);
     }
+        return shiftStr.toString();
+}
 
     public String encrypt(String text) {
-        return text;
+        return crypt(text);
     }
 
     public String decrypt(String text) {
-        return text;
+        return crypt(text);
     }
 
     public static String rotate(String s, Character c) {
-
-        return "";
+        StringBuilder rotated = StringBuilder();
+        //substring: when given one index will slice at that index until length of string
+        String rightHalf = s.substring(s.indexOf(c));
+        //substring: second param is exclusive and won't include indexOf c
+        String leftHalf =s.substring(0, s.indexOf(c));
+        return rotated;
     }
 
 }