最长无重复子串

public class Solution {  
    /** 
     * @param s: a string 
     * @return: an integer  
     */  
    public int lengthOfLongestSubstring(String s) {  
        // write your code here  
        if(s.length()==0){  
            return 0;  
        }  
        int maxLength=1;  
        List<Character> list=new ArrayList<Character>();  
        list.add(s.charAt(0));  
        for(int i=1;i<s.length();i++){  
            if(list.contains(s.charAt(i))){  
                int index=list.indexOf(s.charAt(i));  
                list=list.subList(index+1, list.size());  
                list.add(s.charAt(i));  
//              System.out.println(list);  
                maxLength=Math.max(maxLength, list.size());  
            }else{  
                list.add(s.charAt(i));  
                maxLength=Math.max(maxLength, list.size());  
            }  
        }  
        return maxLength;  
    }  
}