private static String removeDuplicateChar(String input) {
        String result = "";
        char[] tmp = input.toCharArray();
        int i = 0;
        while(i < tmp.length){
            boolean repeat = false;
            for(int j = 0; j < i; j++){
                if(tmp[i] == tmp[j])
                    repeat = true;
            }
            if(repeat == false)
                result = result + tmp[i];
            i++;
        }
        return result;
    }