Longest Substring With Repeating Characters

public class Solution {
public int lengthOfLongestSubstring(String s) {

HashSet<Character> set = new HashSet<Character>();
char[] ch = s.toCharArray();
int left = 0, right = 0;
int result = 0;
while (right < ch.length) {
if (!set.contains(ch[right])) {
set.add(ch[right]);
result = Math.max(result, (right - left + 1));
} else {
while (ch[left] != ch[right]) {
set.remove(ch[left]);
left++;
}
left++;
}
right++;
}
return result;
}
}