public static void main(String[] args) {

        List<WeighOrderCartExtendVO> extendVOs = new ArrayList<>();
        //根据售卖类型分组

        WeighOrderCartExtendVO extendVO = new WeighOrderCartExtendVO();

        extendVO.setDishId("e04b0220006813fb");
        extendVO.setGoodsWeight(100);
        extendVO.setSellType(1);
        extendVO.setGoodsNum(10);
        extendVOs.add(extendVO);


        String extendInfo = JSON.toJSONString(extendVOs);
        JSONObject object = JSON.parseObject(extendInfo);
        // JSONArray array = JSON.parseArray(extendInfo);
        // System.out.println(JSONObject.parseObject(array.get(0).toString()));
    }

Exception in thread "main" com.alibaba.fastjson.JSONException: can not cast to JSONObject.
    at com.alibaba.fastjson.JSON.parseObject(JSON.java:249)
    at com.ut.cook.weigh.order.WeighOrderService.main(WeighOrderService.java:669)
Caused by: java.lang.ClassCastException: com.alibaba.fastjson.JSONArray cannot be cast to com.alibaba.fastjson.JSONObject
    at com.alibaba.fastjson.JSON.parseObject(JSON.java:247)
    ... 1 more

解决: 取出JSONArray中的数据后再解析！