caesar cipher java offset问题和加密

Question

我对不同符号的IF和IF ELSE语句因某些原因而无法正常工作。我无法弄清楚为什么。当我输入“abcd：;”对于带有偏移“1”的文本和选择加密，我收到错误

java.util.InputMismatchException
    at java.util.Scanner.throwFor(Unknown Source)
    at java.util.Scanner.next(Unknown Source)
    at java.util.Scanner.nextInt(Unknown Source)
    at java.util.Scanner.nextInt(Unknown Source)
    at Lab2.main(Lab2.java:132)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at edu.rice.cs.drjava.model.compiler.JavacCompiler.runCommand(JavacCompiler.java:272)

当我输入“abcd：;”时对于带有偏移“1”的文本和选择加密，我得到“BCDE- ^”。似乎空间正在引发问题。

import java.io.*;
import java.util.Scanner;

public class Lab2
{

  public static String encode(String original, int offset)
   {
      // declare constants
      final int ALPHABET_SIZE = 26;  // used to wrap around A-Z
      String encoded = "";           // base for string to return
      char letter;                   // letter being processed

      // convert message to upper case
      original = original.toUpperCase();

      // process each character of the message
      for (int index = 0; index < original.length(); index++)
      {
         // get the letter and determine whether or not to
         // add the cipher value
         letter = original.charAt(index);

         if (letter >='A' && letter <= 'Z')           
         {
            // is A-Z, so add offset 
            // determine whether result will be out of A-Z range
            if ((letter + offset) > 'Z') // need to wrap around to 'A'
               letter = (char)(letter - ALPHABET_SIZE + offset);
            else
               if ((letter + offset) < 'A') // need to wrap around to 'Z'
                  letter = (char)(letter + ALPHABET_SIZE + offset);
               else
                  letter = (char)(letter + offset);            
         }
         // change space to '~'
          if (letter == ' ')
          {
             letter = (char)(126);
          }          
          // change colon to '-'
          else if (letter == ':')
          {
             letter = (char)(45);
          }          
          // change semi colon to '^'
          else if (letter == ':')
          {
             letter = (char)(94);
          }
          // change period to '&'
           else if (letter == '.')
          {
             letter = (char)(38);
          }
           // change hyphen to '$'
           else if (letter == '-')
          {
             letter = (char)(36);
          }
          // change exclamation point to '('
           else if (letter == '!')
          {
             letter = (char)(40);
          }
          // change question marke to ')'
           else if (letter == '?')
          {
             letter = (char)(41);
          }
          // change all other keyboard characters to '%'
        else if (letter == '1')
          {
             letter = (char)(37);
          }

         // build encoded message string
         encoded = encoded + letter;
      }   
      return encoded;
   }

  public static String decode(String original, int offset)
   {
      // declare constants
      final int ALPHABET_SIZE = 26;  // used to wrap around A-Z
      String decoded = "";           // base for string to return
      char letter;                   // letter being processed

      // make original message upper case
      original = original.toUpperCase();

      // process each letter of message
      for (int index = 0; index < original.length(); index++)
      {
         // get letter and determine whether to subtract cipher value
         letter = original.charAt(index);
         if (letter >= 'A' && letter <= 'Z')           
         {
            // is A-Z, so subtract cipher value
            // determine whether result will be out of A-Z range
            if ((letter - offset) < 'A')  // wrap around to 'Z'
               letter = (char)(letter + ALPHABET_SIZE - offset);
            else
               if ((letter - offset) > 'Z') // wrap around to 'A'
                  letter = (char)(letter - ALPHABET_SIZE - offset);
               else
                  letter = (char) (letter - offset);
         }

         // build decoded message
         decoded = decoded + letter;
      }   

      return decoded;
   }

   public static void main(String[] args)
  {
    //Scan for Method
    Scanner scan = new Scanner(System.in);
    System.out.println("Please input 1 to encrypt and 2 to decrypt");
      int action = scan.nextInt();

      //If encryption is picked
      if (action == 1)
      {
        System.out.println("Please input the text to be Encrypted");
        String original = scan.next();

        System.out.println("Please input shift value");
        int offset = scan.nextInt();

        System.out.println(encode(original, offset));
      }
      else if (action == 2)
      {
        System.out.println("Please input the text to be Decrypted");
        String original = scan.next();

        System.out.println("Please input shift value");
        int offset = scan.nextInt();

        System.out.println(decode(original, offset));
      }

   }    
}