CaesarCipher program that output a text file in java

Question

I am trying to build a program that takes a text file, apply CaesarCipher method and returns and output file.

import java.util.*;
import java.io.*;

class CaesarCipher
{
    public static void main (String [] args) throws FileNotFoundException {
        System.out.print("What is the input file name? ");
        Scanner keyboard = new Scanner(System.in);
        String fileName = keyboard.nextLine();
        Scanner inputFile = new Scanner (new File (fileName));
        String inputFileString = inputFile.toString();
        System.out.print("What is the input file name? ");
        int s = 4;
        System.out.println("Text  : " + inputFileString);
        System.out.println("Shift : " + s);
        System.out.println("Cipher: " + encrypt(inputFileString, s));
    }

    public static String encrypt(String inputFileString, int s) {
        StringBuilder result = new StringBuilder();

        for (int i=0; i< inputFileString.length(); i++) {
            if (Character.isUpperCase(inputFileString.charAt(i))) {
                char ch = (char)(((int)inputFileString.charAt(i) + s - 65) % 26 + 65);
                result.append(ch);
            }
            else {
                char ch = (char)(((int)inputFileString.charAt(i) + s - 97) % 26 + 97);
                result.append(ch);
            }
        }

        return result.toString();
    }
}

I have two questions: 1- The program is compiling but when I run it and enter the text file name I get this error:

What is the input file name? Text : java.util.Scanner[delimiters=\p{javaWhitespace}+][position=0][match valid=false][need input=false][source closed=false][skipped=false][group separator=\,][decimal separator=.][positive prefix=][negative prefix=\Q-\E][positive suffix=][negative suffix=][NaN string=\Q�\E][infinity string=\Q∞\E]

2- How can I construct a new outPut file that contains the coded text?

Answer 1

It worked with StringBuilder

StringBuilder inputFileString = new StringBuilder();
        while (inputFile.hasNext()) {
            String x = inputFile.nextLine();
            inputFileString.append(x);
        }