Hello-World using Caesar-Cipher

programs/HelloWorld_CaesarCipher.java

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+
+import java.io.IOException;
+import java.util.Scanner;
+
+public class caesarCiphr {
+
+    //caesarCipher encryption function below.
+    static String caesarCipher(String s, int k) {
+
+        StringBuilder sb = new StringBuilder(s.length());
+
+        for(int i=0;i<s.length();i++){
+            char sc = s.charAt(i);
+            int c = s.charAt(i);
+            if(Character.isAlphabetic(sc)){
+                if(c>=65 && c<=90){
+                    int ct = (c + k - 65) % 26 + 65;
+                    char t = (char) ct;
+                    sb.append(t);
+                }
+                if(c>=97 && c<=122){
+                    int ct = (c + k - 97) % 26 + 97;
+                    char t = (char) ct;
+                    sb.append(t);
+                }
+            }
+            else{
+                char t = (char) c;
+                sb.append(t);
+            }
+        }
+        return sb.toString();
+    }
+    //caesarDeCipher Decryption function below.
+    static String caesarDeCipher(String s, int k) {
+
+        StringBuilder sb = new StringBuilder(s.length());
+
+        for(int i=0;i<s.length();i++){
+            char sc = s.charAt(i);
+            int c = s.charAt(i);
+            if(Character.isAlphabetic(sc)){
+                if(c>=65 && c<=90){
+                    int ct = (c - k - 65) % 26 + 65;
+                    char t = (char) ct;
+                    sb.append(t);
+                }
+                if(c>=97 && c<=122){
+                    int ct = (c - k - 97) % 26 + 97;
+                    char t = (char) ct;
+                    sb.append(t);
+                }
+            }
+            else{
+                char t = (char) c;
+                sb.append(t);
+            }
+        }
+        return sb.toString();
+    }
+    private static final Scanner scanner = new Scanner(System.in);
+
+    public static void main(String[] args) throws IOException {
+
+        System.out.println("Enter the String you want to encrypt : ");
+        String s = scanner.nextLine();
+
+        System.out.println("Enter the key for encryption : ");
+        int k = scanner.nextInt();
+        scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");
+
+        String result = caesarCipher(s, k);
+
+        String plainText = caesarDeCipher(result, k);
+
+        System.out.println("Cipher Text: "+result);
+
+        System.out.println("Original Text : "+plainText);
+
+        scanner.close();
+    }
+}