345 Reverse Vowels of a String

Write a function that takes a string as input and reverse only the vowels of a string.

Example 1:
Given s = "hello", return "holle".

Example 2:
Given s = "leetcode", return "leotcede".

Note:
The vowels does not include the letter "y".

String vowels = "aeiouAEIOU";

char[] sch = s.toCharArray();

start++;

end--;

class Solution {
    public String reverseVowels(String s) {
        if (s == null || s.length() == 0) {
            return s;
        }
        String vowels = "aeiouAEIOU";
        char[] sch = s.toCharArray();

        int start = 0;
        int end = s.length() - 1;
        while (start < end) {
            while (start < end && vowels.indexOf(sch[start]) == -1) {
                start++;
            }
            while (start < end && vowels.indexOf(sch[end]) == -1) {
                end--;
            }
            if (start < end) {
                char temp = sch[start];
                sch[start] = sch[end];
                sch[end] = temp;
                start++;
                end--;
            }

        }
        return String.valueOf(sch);
    }
}