凱撒密碼與Java代碼 - 只會讀大寫

Question

我只是一個開始的程序員，我在這裏找到我的程序中的錯誤。該程序只能讀取我的文本文件中的大寫字母，即使在我的加密和解密方法中使用了小寫字母。我猜這是caesarEncipher方法的問題。 （忽略我的慾海情況下，在主，我會很快得到它。）

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

public class Cipher { 

    public static void main(String[] args) throws FileNotFoundException { 
     Scanner scan = new Scanner(System.in); 
     System.out.println("Welcome to CaesarCipher"); 
     System.out.println(); 
     System.out.println("Enter 1 to Encipher, 2 to Decipher, or -1 to exit"); 
     int choice = 0; 
     do { 
      choice = scan.nextInt(); 
      if (choice == 1) { 
       System.out.println("What non-negative shift should be used?"); 
       int shift = scan.nextInt(); 
       System.out.println("What is the input file name?"); 
       String input = scan.next(); 
       System.out.println("What is the output file name?"); 
       String output = scan.next(); 
       System.out.println(caesarEncipher(input, shift, output)); 
      } else if (choice == 2) { 

      } else if (choice == -1) { 
       System.out.println("Thank you for using CaesarCipher"); 
       break; 
      } 
     } while (choice != 1 && choice != 2 && choice != -1); 
    } 

    public static String caesarEncipher(String inputString, int shift, String output) throws FileNotFoundException { 
     File outFile = new File(output); 
     PrintStream encoded = new PrintStream(outFile); // creates new file for the output 
     File input = new File(inputString); // creates file with String to scan 
     Scanner scan = new Scanner(input); // creates Scanner 
     while (scan.hasNextLine()) { 
      String cipher = scan.nextLine();   // gets next line of file 
      String encipher = "";     // String to be added to new file 
      int i; 
      for (i = 0; i < cipher.length(); i++) { 
       String curr = cipher.substring(i, i + 1); // current character 
       String newChar = encrypt(curr, shift); 
       encipher = encipher + newChar; 
      } 
      encoded.println(encipher); 
     } 
     encoded.close(); 
     return "DONE"; 
    } 

    public static String encrypt(String str, int shift) { 
     String encrypted = ""; 
     for (int i = 0; i < 1; i++) { 
      int c = str.charAt(i); 
      if (Character.isUpperCase(c)) {//if uppercase 
       c = c + (shift % 26); 
       if (c > 'Z') { //resets if it passes 'Z' 
        c = c - 26; 
       } else if (Character.isLowerCase(c)) {// if lowercase 
        c = c + (shift % 26); 
        if (c > 'z') { // resets if it passes 'z' 
         c = c - 26; 
        } 
       } 
       encrypted = encrypted + (char) c; // adds the encrypted character to the string 
      } 
     } 
     return encrypted; 
    } 

    public static String decrypt(String str, int shift) { 
     String decrypted = ""; 
     for (int i = 0; i < 1; i++) { 
      int c = str.charAt(i); 
      if (Character.isUpperCase(c)) //if uppercase 
      { 
       c = c + (shift % 26); 
       if (c < 'A') { //resets if it passes 'A' 
        c = c + 26; 
       } 
      } else if (Character.isLowerCase(c)) // if lowercase 
      { 
       c = c + (shift % 26); 
       if (c < 'a') { // resets if it passes 'a' 
        c = c + 26; 
       } 
      } 
      decrypted = decrypted + (char) c; // adds the derypted character to the string 
     } 
     return decrypted; 
    } 
} 

Answer 1

在encrypt()方法：這部分代碼

else if(Character.isLowerCase(c)) { 
     c=c+(shift%26); 
     if(c>'z') { 
      c=c-26; 
     } 
    } 
    encrypted=encrypted+(char)c; 

屬於if(c>'Z')代替if(Character.isUpperCase(c))