java - pig 拉丁语程序 - 元音问题

Question

我正在编写一个有两个规则的程序:
1. 如果单词的第一个字符是元音，则将其移至单词的末尾。
2. 如果单词的第一个字符是辅音，则将其移动到单词的末尾并附加“ae”。

import java.util.Scanner;

public class Program5 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner scanner = new Scanner(System.in);
        System.out.print("Please enter a sentence: ");
        String english = scanner.nextLine();
        String piggy = piggyEnglish(english);
        System.out.print("Translated: " + piggy);
    }
     private static String piggyEnglish(String s) {
            String piggy = "";
            int i = 0;
            while (i<s.length()) {

              while (i<s.length() && !isLetter(s.charAt(i))) {
                piggy = piggy + s.charAt(i);
                i++;
              }

              if (i>=s.length()) break;

              int begin = i;
              while (i<s.length() && isLetter(s.charAt(i))) {
                i++;
              }

              int end = i;
              piggy = piggy + piggyWord(s.substring(begin, end));
            }
            return piggy;
          }

     private static boolean beginsWithVowel(String word){
              String vowels = "aeiou";
              char letter = word.charAt(0);
              return (vowels.indexOf(letter) != -1);
              }

     private static boolean isLetter(char c) {
        return ( (c >='A' && c <='Z') || (c >='a' && c <='z') );
      }

    private static String piggyWord(String word) {
            int split = firstVowel(word);
            if(beginsWithVowel(word)) {
                return word.substring(split) + word.substring(0, split);
            } else {
            return word.substring(split) + word.substring(0, split)+"ae";
            }
    }       

    private static int firstVowel(String word) {
        word = word.toLowerCase();
        for (int i=0; i<word.length(); i++)
          if (word.charAt(i)=='a' || word.charAt(i)=='e' ||
              word.charAt(i)=='i' || word.charAt(i)=='o' ||
              word.charAt(i)=='u')
            return i;
        return 0;
    }
}

以下是预期输出:

Please enter a sentence: today is a beautiful day 
Translated: odaytae si a eautifulbae aydae

但是，这就是我得到的:

Please enter a sentence: today is a beautiful day
Translated: odaytae is a eautifulbae aydae

基本上，它不会翻译任何以元音开头的单词。我认为问题源于 PiggyWord 方法，但我不确定。我可以获得有关如何解决此问题的任何指示吗？

Answer 1

错误在于 piggyWord 函数:

private static String piggyWord(String word) {
        int split = firstVowel(word);
        if(beginsWithVowel(word)) {
            return word.substring(split + 1) + word.substring(0, split + 1); //Since vowel is in 1st place, substring(0,0) returns empty string.
        } else {
        return word.substring(split) + word.substring(0, split)+"ae";
        }
}