Will the Guru

class Solution {
    public int lengthOfLongestSubstring(String s) {
        Set<Character> set = new HashSet<>();
        
        int result = 0;
        int left = 0;
        char[] sCharArray = s.toCharArray();
        for (int right=0;right<sCharArray.length;right++) {
            char c = sCharArray[right];
            while(set.contains(c)) {
                set.remove(sCharArray[left]);
                left++;
            }
            set.add(c);
            result = Math.max(result, right - left + 1);
        }
        return result;
    }
}