Ceasar密码方法的解密不工作，并没有打印

-2

我是非常新的编程和无法找出问题与我的Cesar密码我的加密方法工作正常，但我的解密方法不起作用。Ceasar密码方法的解密不工作，并没有打印

主要类

package com.company; 

import java.util.Scanner; 

public class Main { 
    public ceasarCipher ceasarCipher; 

    public static void main(String[] args) { 

     com.company.ceasarCipher utilityClass = new ceasarCipher(); 
     int inShift; 
     String inString; 
     String encryptedString = ""; 

     Scanner sca = new Scanner(System.in); 

     System.out.println("Please enter a string to encrypt"); 
     inString = sca.nextLine(); 

     System.out.println("======================================================================================="); 
     System.out.println("In this program"); 
     System.out.println("Press 1 to encrypt your string by shifting it forward a certain amount"); 
     System.out.println("Press 2 to decipher your string by shifting it backwards a certain amount"); 
     System.out.println("Press 3 to give you all possible combinations of the shift in order to decipher"); 
     System.out.println("Press 4 to exit the program"); 
     System.out.println("======================================================================================="); 

     while(!sca.hasNext("x") && !sca.hasNext("X")){ 

      int userInput; 
      userInput = sca.nextInt(); 

      switch (userInput){ 

       case 1: 
        System.out.println("Please enter the amount greater than 0 that you would like your String to be shifted forwards in order to encrypt it"); 
        inShift = sca.nextInt(); 
        System.out.println(utilityClass.ccEncrypt(inShift,inString)); 
       case 2: 
        System.out.println("Please enter the amount greater than 0 that you would like your String to be shifted backwards in order to decipher it"); 
        inShift = sca.nextInt(); 
        System.out.println(utilityClass.ccDecipher(inShift,encryptedString)); 
      } 
     } 
    } 
}

子类与方法

package com.company; 

/** 
* Created by Jake on 14/04/2017. 
*/ 
public class ceasarCipher { 

    private int maxVal = 26; 

    //private int inShift; 
    //private String inString; 
    private String letters = "abcdefghijklmnopqrstuvwxyz"; 

    //----------------------------------------------------------- 
    public String ccEncrypt (int inShift, String inString) { 

     String encryptedString = ""; 
     char modulo; 
     int pos; 

     inString = inString.toLowerCase(); 

     for (int i = 0; i < inString.length(); i++) { 

      pos = letters.indexOf(inString.charAt(i)); 

      modulo = this.letters.charAt((pos + inShift) % maxVal); 

      encryptedString += modulo; 
     } 
     return encryptedString; 
    } 
    //---------------------------------------------------------------------- 

    public String ccDecipher (int inShift, String encryptedString) { 

     String decipheredString = ""; 
     char modulo; 
     int pos; 

     for (int i = encryptedString.length() - 1; i >= 0; i--) { 

      pos = letters.indexOf(encryptedString.charAt(i)); 

      modulo = this.letters.charAt((pos - inShift) % maxVal); 

      decipheredString += modulo; 
     } 
     return decipheredString; 
    } 
    // ----------------------------------------------------------------------- 

    public void ccDecipherAll (String inString){ 

    } 
}

来源

2017-04-15 Jake77

你是什么意思*“无需打印”*？至少是否打印“请输入要加密的字符串”？如果是这样，请[编辑]您的问题以显示实际输出以及您的输入。 –

是的，它确实是更具体，它不是打印我的解密方法，在案例2 – Jake77

因此，你输入密文，然后程序结束？这看起来像一个ArrayIndexOutOfBoundsException情况，weston的答案是解决这个问题的恰当方法。你在任何地方看到这个例外吗？仔细观察。 –

你永远不指定任何东西encryptedString。也许你应该使用inString。

System.out.println(utilityClass.ccDecipher(inShift, inString));

如果你想这样做在一个循环中，你可能希望每次更新inString：你希望它是什么

inString = utilityClass.ccDecipher(inShift, inString); //same for encrypt 
System.out.println(inString);

然后，负的模不做：

品牌：

(pos - inShift) % maxVal

分为：

(pos - (inShift % maxVal) + maxVal) % maxVal

确保您不会取模的负数。

您也正在倒退解码。

来源

2017-04-15 19:38:41 weston

Ceasar密码方法的解密不工作，并没有打印

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