Caesar Cipher Solution - CSC 142

CaesarSolution.java

public class CaesarSolution {

    public static String caesarShift(String message, int key, boolean doEncryption) {

        message = message.toUpperCase();
        message = message.replace(" ","");
        
        // This is the variable storing the encrypted/decrypted message
        String message2 = "";
        
        for( int j = 0; j < message.length(); j++ ) {
            char c, c2;
            int ix, ix2;
            c = message.charAt(j);

            // Deal with non-letter characters using user-specified strategy

            if( c >= 'A' && c <= 'Z' ) {
                // Apply Caesar shift to letters
                ix = (int)(c - 'A');

                if( doEncryption ) {
                    ix2 = (ix + key)%26;
                } else {
                    // have to add 26 to ensure everything positive, because -1 mod 26 does not become 25
                    ix2 = (26 + ix - key)%26;
                }

                c2 = (char)('A' + ix2);

                // append to message
                message2 += c2;

            }
            // ignore punctuation
        }

        return message2;
    }
    public static void main(String[] args) {
    	
        System.out.println( caesarShift("Gaul is divided into three parts", 5, true) );

    }
	
}