Project Number 5 and Caesar Cipher

Code

    /// Name: Brendan Baird
    /// Period: 6
    /// Program Name: Caesar Cipher
    /// File Name: CaesarCipher.java
    /// Date Finished: 5/9/2016
    
    import java.util.Scanner;
    import java.io.File;
    import java.io.IOException;
    import java.io.PrintWriter;
    
    public class CaesarCipher {
    
        public static char shiftLetter(char c, int n) {
    
            int u = c;
    
            if(!Character.isLetter(c))
                return c;
    
            u = u + n;
    
            if(Character.isUpperCase(c) && u > 'Z' || Character.isLowerCase(c) && u > 'z') {
                u -= 26;
            }
    
            if(Character.isUpperCase(c) && u < 'A' || Character.isLowerCase(c) && u < 'a') {
                u += 26;
            }
    
            return (char)u;
        }
    
        public static void main(String[] args) throws Exception {
    
            PrintWriter fileOut;
            Scanner input = new Scanner(System.in);
            String file1, file2, cipher = "";
            int shift;
            
            System.out.print("\nWould you like to encrypt or decrypt a message? ");
            String cryptChoice = input.next();
            
            System.out.print("\nWhich file would you like to choose: ");
            file1 = input.next();
            
            System.out.println();
            System.out.print("Shift (0 - 26): ");
            shift = input.nextInt();
            
            Scanner fileReader = new Scanner(new File(file1));
    
            System.out.println("Message:\n");
            
            while(fileReader.hasNext()){
                String line = fileReader.nextLine();
                System.out.println(line); //prints chosen message to console
    
                if (cryptChoice.equals("Decrypt") || cryptChoice.equals("decrypt")){
                    shift = -1 * shift;
                }
                    
                for(int i = 0; i < line.length(); i++) { 
                    cipher += shiftLetter(line.charAt(i), shift);
                    
                } //shifts message by a number of characters depending on decryption or encryption
    
            }
            fileReader.close();
            
            System.out.println("\n" + cipher);
            System.out.print("What should the name of the message be? ");
            file2 = input.next();
            
            try{
                fileOut = new PrintWriter(file2 + ".txt");
                
            } catch(IOException e) {
                System.out.println("Sorry, I can't open the file.");
                fileOut = null;
                System.exit(1);
            }
            
            fileOut.println(cipher);
            
            fileOut.close();
        }
    
    
    }
    

Picture of the output