Find longest substring without repeating characters

Question

Given a string S of length N find longest substring without repeating characters.

Example:

Input:

Answer 1

Tested and working. For easy understanding, I suppose there's a drawer to put the letters.

Function:

    public int lengthOfLongestSubstring(String s) {
        int maxlen = 0;
        int start = 0;
        int end = 0;
        HashSet drawer = new HashSet(); 
        for (int i=0; imaxlen) {
                    maxlen=_maxlen;
                }
            }
        }
        return maxlen;
    }