Simple logic error in cipher-shifting program?

[A Axford]

Hello! Thanks for clicking on this post. I could use a fresh pair of eyes.
I was tasked with creating a program that encrypts a line of text (for example, CANDY) by shifting the letters X amount of times. For example, if the user inputs the sentence CANDY and selects a shift of 5, the output would be:
HFSID
I got this part working fine. The issue I am having is with the decryption part of the program. This is simply the reverse of the above, as the user would enter the phrase HFSID, with a shift of 5, and the program would output:
CANDY
It works fine, all except for one letter, being the "F" letter. With my code, when I enter the above word to be decrypted it outputs:
C[NDY
Obviously, that [ bracket is not an 'A'. I realise the issue falls with the equation, but upon messing around with the program for about four hours, it is all starting to blur together. I just need a point in the right direction...
Here is my code:

public class SimpleEncryption {

    /**
     * @param args the command line arguments
     */
 static int answer;
    public static void main(String[] args) {
        String cipher = JOptionPane.showInputDialog(null, "Please enter a sentence or word that you wish to encode or decode. This program uses"
                + " a basic cipher shift.");

        String upperCase = cipher.toUpperCase();
        char[] cipherArray = cipher.toCharArray();
        String rotationAmount = JOptionPane.showInputDialog(null, "Please enter a shift amount.");
        int rotation = Integer.parseInt(rotationAmount);
        String encryptOrDecrypt = JOptionPane.showInputDialog(null, "Please choose whether to encrypt or decrypt this message. \n"
                + "Encrypt - press 1\nDecrypt - press 2");
        int choice = Integer.parseInt(encryptOrDecrypt);
        int cipherLength = cipherArray.length;
        if (choice == 1) { //if the user chooses to encrypt their cipher
            System.out.println("The original phrase is: " + upperCase);
            System.out.println("ENCRYPTED PHRASE:");
            for (int i = 0; i < cipherLength; i++) {
                int shift = (cipher.charAt(i) - 'A');
                int check = (shift + rotation) % 26; 
                 answer = check + 'A';
                System.out.print((char) (answer));
            }
            System.out.println(" ");
        } else if (choice == 2) {
            System.out.println("The original phrase is " + upperCase);
            System.out.println("DECRYPTED PHRASE:");
            for (int i = 0; i < cipherLength; i++) {
                int shift = cipher.charAt(i) - 'A';
                int check = (shift - rotation) % 25;
                if (check < 1) {
                    check = (shift - rotation) % 26 + 26;
                }
                answer = check + 'A'; 
                System.out.print((char) (answer));
            }
            System.out.println(" ");
        }

Any help is appreciated!

[Carey Brown]

Line 34: I think you meant 26 not 25.
Line 35: Less than zero.
Line 36: rethink this formula.
I would also correct for negative values before doing the modulus.

[Stephan van Hulst]

Why isn't your decryption a simple reversal of your encryption?

You can reverse the modulus by simply adding 26 once and then applying the modulus.

( 5 + 26) % 26 = 5
(-2 + 26) % 26 = 24