將list分爲大小相等的小組

public static  <T> List<List<T>> packList(List<T> list, int len) {
        if (list == null || list.size() == 0 || len < 1) {
            return null;
        }
        List<List<T>> result = new ArrayList<List<T>>();
        int size = list.size();
            int mod = size%len;//第一種算法
        if(mod!=0){
            count=size/len+1;
        }else{
            count=size/len;
        }
//      int count = (size + len - 1) / len; //第二種算法  
        for (int i = 0; i < count; i++) {
            List<T> subList = list.subList(i * len, ((i + 1) * len > size ? size : len * (i + 1)));
//          List subl = new ArrayList<>();
//          subl.addAll(subList);這個可用於當強轉類型報 can not cast be...時用這個，寫在強轉處
            result.add(subList);
        }
        return result;
    }