如何为加密文本保留空格

Question

class Main {
  public static void main(String[] args) {
    String alphabet = "abcdefghijklmnopqrstuvwxyz";
    String message = "how are you";
    int shift = -3;

    System.out.println(message);

    String eMessage = "";
   
    if(shift < 0) {
      int newShift = shift % 26 + 26;
      
      for (int i = 0; i < message.length(); i++) {
        int wordPosition = alphabet.indexOf(message.charAt(i));
        int numCipher = (wordPosition + newShift) % 26;
        char cipher = alphabet.charAt(numCipher);
        eMessage = eMessage + String.valueOf(cipher);
    else {  
      int newShift = shift % 26;
      for (int i = 0; i < message.length(); i++) {
        int wordPosition = alphabet.indexOf(message.charAt(i));
        int numCipher = (wordPosition + newShift) % 26;
        char cipher = alphabet.charAt(numCipher);
        eMessage = eMessage + String.valueOf(cipher);
      }
    }
      
    System.out.print(eMessage);
  }
}

它适用于单个单词，但是当我输入完整的句子时，消息的加密版本不会保留任何空格。相反，它将空格更改为 w。如何保留完整句子的空格？ 我需要的例子- 输入：你好吗，输出：elt xob vlr ---- 我得到的例子 - 输入：你好吗，输出：eltwxobwvlr