commit

src/AssessmentPartThree.java

 
 public class AssessmentPartThree {
 
-	// The simplest form of encryption is the rotation cipher (also known as Caeser's Cipher)
-	// An offset value is chosen to encrypt a message. Each letter is replaced by the
+	// The simplest form of encryption is the rotation cipher (also known as
+	// Caeser's Cipher)
+	// An offset value is chosen to encrypt a message. Each letter is replaced by
+	// the
 	// letter that that number of places away from it.
-	// So if an offset value of 1 is chosen, each letter is replaced by the one after it
+	// So if an offset value of 1 is chosen, each letter is replaced by the one
+	// after it
 	// - so a becomes b, b becomes c, etc
 	// If a value of -2 is chosen a becomes y, b becomes z and so on
+	private static String letters = "a";
 
-	 public char enryptedCharacter(char theChar, int theOffset)
-	 {
+	public char enryptedCharacter(char theChar, int theOffset) {
 		// 05 - encryptedCharacter
 		// Complete this method so that it returns the encrypted character for
 		// theChar when and offset of theOffset is used
 		// So if theChar='m' and theOffset is 3 the method will return 'p'
 		// Lower case characters remain lower case, upper case remain upper case
 		// Any other characters are returned unchanged
-		 
-		 return 'a';
+		int index = -1;
+		for (int i = 0; i < letters.length(); i++) {
+			char ch = letters.charAt(i);
+			if (ch == theChar) {
+				index = i;
+			}
+		}
+		if (index == -1) {
+			for (int i = 0; i < letters.toUpperCase().length(); i++) {
+				char ch = letters.toUpperCase().charAt(i);
+				if (ch == theChar) {
+					index = i;
+				}
+			}
+			if (index == -1)
+				return theChar;
+			else {
+				if (theOffset < 0) {
+					if (index + theOffset < 0)
+						return letters.toUpperCase().charAt(26 + (index + theOffset) % 26);
+					return letters.toUpperCase().charAt(index + theOffset % 26);
+				}
+				return letters.toUpperCase().charAt(index + theOffset % 26);
+			}
+		}
+		if (theOffset < 0) {
+			if (index + theOffset < 0)
+				return letters.charAt(26 + (index + theOffset) % 26);
+			return letters.charAt(index + theOffset % 26);
+		}
+		return letters.charAt(index + theOffset % 26);
 	}
 
-	 public String encryptedString(String theMessage, int theOffset)
-	 {
+	public String encryptedString(String theMessage, int theOffset) {
 		// 06 - encryptedMessage
 		// Complete this method so that it uses encryptedCharacter to
 		// return the encrypted version of theMessage using theOffset
-		 
-		 return "Encryptred message";
+		String str = "";
+		if (null != theMessage && !theMessage.trim().isEmpty()) {
+			for (int i = 0; i < theMessage.length(); i++) {
+				str += enryptedCharacter(theMessage.charAt(i), theOffset);
+			}
+		}
+		return str;
 	}
 
 }