Simple Java Encryption/Decription - (Error: unexpected type || required: variable found: value)
<p>I'm trying to help a colleague decode a letter from his friend, and he's sick of doing the math on his own.  I took it as an opportunity to try to use Java to help him decrypt it a little faster with the computer doing the math.  I initially tried to do blocks of 5 characters at a time, but my arrays were a mess and he thought he'd like to do it one character at a time anyway.  Any help would be greatly appreciated.</p>

<p>Below is my code:</p>

<pre><code>import java.io.*;
class CharlieEncryption
{
    public static void main(String args[]) throws IOException
    {
        CharlieEncryption app;
        app = new CharlieEncryption();
        app.appMain();
    }

    BufferedReader stdin;
    String inString;
    String encrypt;
    String decrypt;

    String[] alphabet = {"A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","Y","X","Z"};
    String letter;
    int letter_code = 0;
    int number_code = 0;
    int letter_num = 0;
    int finish_letter_num = 0;
    String finish_letter;

    // appMain module (Call all modules here)
    public void appMain() throws IOException
    {
        Input();
        Mode();

        if(encrypt.equals("Y"))
        {
            Encrypt();
            Output();
        }
        else
        {
            Decrypt();
            Output();
        }
    }
    //Module to recieve Input
    void Input() throws IOException
    {
        //Requesting Input
            System.out.print("Please input character");
            letter = stdin.readLine();
        //Converting Letter to Number
            for(int j = 0; j &lt; 25; j++)
            {
                if(letter.equals(alphabet[j]))
                {
                    letter_num = j;
                }
            }

        //Requesting Input for Code
            System.out.println("Please input code for the character");
            inString = stdin.readLine();
            number_code = Integer.parseInt(inString);               
    }

    //Module to ask if user wants to encrypt or decrypt
    void Mode() throws IOException
    {
        System.out.println("Would you like to encrypt? Y or N");
        encrypt = stdin.readLine();

        if(encrypt.equals("N"))
        {
            System.out.println("Would you like to decrypt? Y or N");
            decrypt = stdin.readLine();
        }
    }
    //Module to Encrypt Text
    void Encrypt()
    {
            (letter_num) + (number_code) = finish_letter_num;
        //Converting the finished number to a letter
        for(int i = 0; i &lt; 25; i++)
        {
            if(finish_letter_num == i)
            {
                finish_letter = alphabet[i];
            }
        }           
    }
    //Module to Decrypt Text
    void Decrypt()
    {
            (letter_num) - (number_code) = finish_letter_num;
        //Converting the finished number to a letter
        for(int i = 0; i &lt; 25; i++)
        {
            if(finish_letter_num == i)
            {
                finish_letter = alphabet[i];
            }
        }   
    }
    //Module to Output Encrypted Text OR Decrypted Text
    void Output()throws IOException
    {
            System.out.println("Result" + finish_letter);
    }

}
</code></pre>

<p>Below are the errors:</p>

<pre><code>    CharlieEncryption.java:78: error: unexpected type
            (letter_num) + (number_code) = finish_letter_num;
                         ^
      required: variable
      found:    value
    CharlieEncryption.java:91: error: unexpected type
            (letter_num) - (number_code) = finish_letter_num;
                         ^
      required: variable
      found:    value
    2 errors
</code></pre>

<p>Any help would be greatly appreciated.  I'm not a Java guru at ALL, as you can probably tell by my code... LOL.  Trying to read all these other people's issues with this error just made my head hurt because I couldn't grasp the code they were having the issues with in the first place.</p>

<p>Thank you!</p>
