Update Caesar.java

ciphers/Caesar.java

@@ -1,105 +1,96 @@
-/**
+package ciphers;
-Author : FAHRI YARDIMCI
 
-A Java implementation of Caesar Cipher.
-/It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. /
-**/
 import java.util.Scanner;
+
+/**
+ *
+ * A Java implementation of Caesar Cipher. /It is a type of substitution cipher
+ * in which each letter in the plaintext is replaced by a letter some fixed
+ * number of positions down the alphabet. /
+ *
+ * @author FAHRI YARDIMCI
+ * @author khalil2535
+ */
 public class Caesar {
-public static String encode (String message,int shift)
+
-{
+    /**
+     * Encrypt text by shifting every Latin char by add number shift for ASCII
+     * Example : A + 1 -> B
+     *
+     * @param message
+     * @param shift
+     * @return Encrypted message
+     */
+    public static String encode(String message, int shift) {
         String encoded = "";
-	for(int i = 0 ; i<message.length() ;i++)
-	{
-		int current = message.charAt(i); //using char to shift characters because ascii is in-order latin alphabet
-		if(current==32)
-		{
-			encoded += " ";
-			continue;
 
+        while (shift >= 26) { // 26 = number of latin letters
+            shift -= 26;
         }
-		else if (current>=65 && current<= 90)
-		{
-			int numAlphabet = message.charAt(i);
-			if(shift + numAlphabet > 90)
-			{
-				int j = 90 - numAlphabet;
-				char nextKey = (char)(65 + (shift - j - 1));
-				encoded += nextKey;
 
-			}
+        final int length = message.length();
-			else
+        for (int i = 0; i < length; i++) {
-			{
+
-				char nextKey = (char)(current + shift);
+//            int current = message.charAt(i); //using char to shift characters because ascii is in-order latin alphabet
-				encoded += nextKey;
+            char current = message.charAt(i); // Java law : char + int = char
-			}
+
-		}
+            if (current >= 'A' && current <= 'Z') {
-		else if (current>=97 && current <= 122)
+
-		{
+                current += shift;
-			int numAlphabet = message.charAt(i);
+                encoded += (char) (current > 'Z' ? current - 26 : current); // 26 = number of latin letters
-			if(shift + numAlphabet > 122)
+
-			{
+            } else if (current >= 'a' && current <= 'z') {
-				int j = 122 - numAlphabet;
+
-				char nextKey = (char)(97 + (shift - j - 1));
+                current += shift;
-				encoded += nextKey;
+                encoded += (char) (current > 'z' ? current - 26 : current); // 26 = number of latin letters
-			}
+
-			else
+            } else {
-			{
+                encoded += current;
-				char nextKey = (char)(current + shift);
-				encoded += nextKey;
-			}
             }
         }
         return encoded;
     }
-public static String decode (String message,int shift)
+
-{
+    /**
+     * Decrypt message by shifting back every Latin char to previous the ASCII
+     * Example : B - 1 -> A
+     *
+     * @param encryptedMessage
+     * @param shift
+     * @return message
+     */
+    public static String decode(String encryptedMessage, int shift) {
         String decoded = "";
-	for(int i = 0 ; i<message.length() ;i++)
-	{
-		int current = message.charAt(i);
-		if(current==32)
-		{
-			decoded += " ";
-			continue;
 
+        while (shift >= 26) { // 26 = number of latin letters
+            shift -= 26;
         }
-		else if (current>=65 && current<= 90)
-		{
-			int numAlphabet = message.charAt(i);
-			if(numAlphabet - shift < 65)
-			{
-				int j = numAlphabet - 65;
-				char nextKey = (char)(90 - (shift - j - 1));
-				decoded += nextKey;
 
-			}
+        final int length = encryptedMessage.length();
-			else
+        for (int i = 0; i < length; i++) {
-			{
+            char current = encryptedMessage.charAt(i);
-				char nextKey = (char)(current - shift);
+            if (current >= 'A' && current <= 'Z') {
-				decoded += nextKey;
+
-			}
+                current -= shift;
-		}
+                decoded += (char) (current < 'A' ? current + 26 : current);// 26 = number of latin letters
-		else if (current>=97 && current <= 122)
+
-		{
+            } else if (current >= 'a' && current <= 'z') {
-			int numAlphabet = message.charAt(i);
+
-			if(numAlphabet - shift < 97)
+                current -= shift;
-			{
+                decoded += (char) (current < 'a' ? current + 26 : current);// 26 = number of latin letters
-				int j = numAlphabet - 97;
+
-				char nextKey = (char)(122 - (shift - j - 1));
+            } else {
-				decoded += nextKey;
+                decoded += current;
-			}
-			else
-			{
-				char nextKey = (char)(current - shift);
-				decoded += nextKey;
-			}
             }
         }
         return decoded;
     }
-public static void main(String[] args)
+
-{
+    /**
+     *
+     * @deprecated TODO remove main and make JUnit Testing
+     */
+    public static void main(String[] args) {
         Scanner input = new Scanner(System.in);
         System.out.println("Please enter the message (Latin Alphabet)");
         String message = input.nextLine();
@@ -108,10 +99,12 @@ public static void main(String[] args)
         int shift = input.nextInt() % 26;
         System.out.println("(E)ncode or (D)ecode ?");
         char choice = input.next().charAt(0);
-	if(choice == 'E' || choice=='e')
+        if (choice == 'E' || choice == 'e') {
             System.out.println("ENCODED MESSAGE IS \n" + encode(message, shift)); //send our function to handle
-	if(choice =='D' || choice =='d')
+        }
+        if (choice == 'D' || choice == 'd') {
             System.out.println("DECODED MESSAGE IS \n" + decode(message, shift));
         }
+    }
 
 }