Assignemnt Project #5 and Caesar Cipher

Code

    ///Name: Daniel Tiffany-Appleton
    ///Period: 7
    ///Program Name: Caesar Cipher
    ///File Name: CaesarCipher
    ///Date Finished: 4/12/16
    
    import java.io.File;
    import java.io.PrintWriter;
    import java.util.Scanner;
    
    public class CaesarCipher 
    {
    
         public static void main(String[] args) throws Exception
        {
    
            Scanner input = new Scanner(System.in);
    
            PrintWriter fileOut;
            String plainText, cipher ="", choice, fileName, fileNaming;
            int shift;
    
            System.out.print("Which file has your message? ");
            fileName = input.nextLine();
             
            Scanner fileIn = new Scanner(new File(fileName));
            
            plainText = fileIn.nextLine();
            fileIn.close();
             
            System.out.print("Want to encrypt or decrypt a message? ");
            choice = input.nextLine();
            
            if(choice.equals("encrypt"))
            {   
                System.out.print("Shift (0 - 26): ");
                shift = input.nextInt();
    
                for(int i = 0; i < plainText.length(); i++) 
                {
                    cipher += shiftLetter(plainText.charAt(i), shift, choice);
                }
    
            }
               
            else if(choice.equals("decrypt"))
            {
                System.out.print("Shift (0 - 26): ");
                shift = input.nextInt();
    
                for(int i = 0; i < plainText.length(); i++) 
                {
                    cipher += shiftLetter(plainText.charAt(i), shift, choice);
                }
    
            }
            
            System.out.print("What do you want to call your message? ");
            fileNaming = input.next();
            
            fileOut = new PrintWriter(new File(fileNaming));
             
            fileOut.println( cipher );
            fileOut.close();
        }
        
        public static char shiftLetter(char c, int n, String choice) 
        {
    
            int u = c;
    
            if(!Character.isLetter(c))
                return c;
    
            if(choice.equals("encrypt"))
            {
                u = u + n;
            }
            
            else if(choice.equals("decrypt"))
            {
                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;
        }
    
    }


    

Picture of the output