Longest Substring Without Repeating Characters

#

class Solution {
    public int lengthOfLongestSubstring(String s) {

        int j=0;
        HashSet<Character> set=new HashSet<>();
        int res=0;
        for(int i=0;i<s.length();i++)
        {
            while(set.contains(s.charAt(i)))
            {
                set.remove(s.charAt(j));
                j+=1;
            }
                set.add(s.charAt(i));
                res=Math.max(res,set.size());
            }
            return res;
        }

    
    }