public void start() {

    do {

      System.out.println("--> SELECT A FUNCTION.");
      System.out.println("--> * 0. Finish JSecretStrings");
      System.out.println("--> * 1. Encrypt String using standard algorithms");
      System.out.println("--> * 2. Decrypt String using standard algorithms");
      System.out.println("--> * 3. Multiple words encryption using alternative algorithms");
      System.out.println("--> * 4. Multiple words decryption using alternative algorithms");

      System.out.print("\nType your selection: ");
      switch (scanner.nextInt()) {
        case 0:
          System.out.println("--- Good Bye ---");
          System.exit(0);
          break;

        case 1:
          System.out.println("");
          System.out.print("Type string to encrypt: ");
          scanner.nextLine();
          final String toEncrypt = scanner.nextLine();

          System.out.print("Super secret Keyword: ");
          final String keyWord = scanner.nextLine();

          final String encrypted = Crypter.encrypt(toEncrypt, keyWord);
          System.out.println("\nEncrypted string: " + encrypted);
          break;

        case 2:
          System.out.println("");
          System.out.print("Type string to decrypt: ");
          scanner.nextLine();
          final String toDecrypt = scanner.nextLine();

          System.out.print("Super secret Keyword: ");
          final String secretKeyWord = scanner.nextLine();

          final String decrypted = Crypter.decrypt(toDecrypt, secretKeyWord);
          System.out.println("\nDecrypted string: " + decrypted);
          break;

        case 3:
          System.out.println("");
          System.out.print("How many Strings do you want to encrypt? ");
          scanner.nextLine();
          final int wordsToEncryptCount = scanner.nextInt();

          ArrayList<String> wordsToEncrypt = new ArrayList<>();
          scanner.nextLine();
          for (int i = 0; i < wordsToEncryptCount; i++) {
            System.out.print("Type string " + i + ": ");
            wordsToEncrypt.add(scanner.nextLine());
          }

          System.out.print("Super secret keyword: ");
          final String secretWord = scanner.nextLine();

          final String encWords = Crypter.customEncrypt(wordsToEncrypt, secretWord);
          System.out.println("\nEncrypted string: " + encWords);
          break;

        case 4:
          System.out.println("");
          System.out.print("Type string to decrypt: ");
          scanner.nextLine();
          final String wordsToDecrypt = scanner.nextLine();

          System.out.print("Super secret Keyword: ");
          final String superSecretWord = scanner.nextLine();

          final ArrayList<String> decryptedWords =
              Crypter.customDecrypt(wordsToDecrypt, superSecretWord);
          for (String word : decryptedWords) {
            System.out.println("String decrypted: " + word);
          }
          System.out.println("");
          break;

        default:
          System.out.println("Please select a valid option");
      }

      System.out.print("\n[TYPE A CHAR AND ENTER TO CONTINUE] ");
      scanner.next();

    } while (true);
  }