Project #5 and Caesar Cipher

Code

    /// Name: Lauren Baird
    /// Period: 7
    /// Program Name: Caesar Cipher
    /// File Name: P5.java
    /// Date Finished: 3/31/2016
    
    import java.io.IOException;
    import java.io.PrintWriter;
    import java.io.File;
    import java.util.Scanner;
    
    public class P5
    {
        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
        {
            System.out.println();
            Scanner input = new Scanner(System.in);        
    
            String plainText, x, name, message, answer, cipher ="";
            int shift;
            
            System.out.print( "Would you like to encrypt or decrypt a message? " );
            answer = input.nextLine();
            
            System.out.print( "Where is the message located? " );
            message = input.nextLine();
            
             System.out.print( "What would you like to call your " + answer + "ed message? " );
            String newFile = input.nextLine();
            
            System.out.print("Shift (0 - 26): " );
            shift = input.nextInt();
            
            System.out.println();
            
            
            Scanner fileIn = new Scanner(new File(message));
            
            while (fileIn.hasNext())
            {
                x = fileIn.nextLine();
                
                if (answer.equals("encrypt"))
                {
                    for(int i = 0; i < x.length(); i++)
                    {
                        cipher += shiftLetter(x.charAt(i), shift);
                    }
                }
                    
                else if (answer.equals("decrypt"))
                {
                    shift = -1 * shift;
                    
                    for(int i = 0; i < x.length(); i++)
                    {
                        cipher += shiftLetter(x.charAt(i), shift);
                    }
                }                  
            }
            
            fileIn.close();
            
            System.out.println( "Your " + answer + "ed message: " + cipher );
            System.out.println();
            
            PrintWriter fileOut;
            
            try
            {
                fileOut = new PrintWriter( newFile + ".txt" );
            }
            
            catch(IOException e)
            {
                System.out.println( "There has been an error in opening " + newFile + ".txt " );
                fileOut = null;
                System.exit(1);
            }
            
            fileOut.println(cipher);
            fileOut.close();
            
            System.out.println( "Your " + answer + "ed message has been stored in " + newFile + ".txt " );
            
        }
    }