难度有吗？

  class Solution {
    public int lengthOfLongestSubstring(String str) {
        char[] charArray = str.toCharArray();
        List integers = new ArrayList<>(charArray.length);
        List temp = new ArrayList<>();
        int count ;
        for(int i = 0 ; i < charArray.length ; i++){
            temp.add(charArray[i]);
            count = 1;
            for(int j = 1 ; j < charArray.length-i ; j++){
                if(temp.contains(charArray[i+j]))break;
                else{
                    count++;
                    temp.add(charArray[i+j]);
                }
            }
            integers.add(count);
            temp.clear();
        }
        if(integers.size() == 0)return 0;
        count = integers.stream().max(Comparator.comparingInt(Integer::intValue)).get();
        System.out.println(count);
        return count;
    }
}