List,ArrayList函数返回时出错，求教大神

Question

arraylisthashmapList

Answer 1

/*
     * 获取服务器订单 
     * @param String url, HashMap<String,Object> data
     * @return byte[]
     */
    public static List<HashMap<String,Object>> getOrders(String url,HashMap<String,Object> param) throws Exception
    {
        String data =  RedefineHttpRequest.HttpPost(url, param);
        JSONObject msg = new JSONObject(data);
        int error = msg.getInt("error");
        if(error==1)   //返回错误
        {
           android.util.Log.i("data",msg.getString("data"));   
        }
        else if(error==0)   //返回正确
        {
            JSONArray arr =  msg.getJSONArray("data");
            if(arr.length()==0)   //结果为空
            {
                 
            }
            else
            {
                List<HashMap<String,Object>> res = new ArrayList<HashMap<String,Object>>();   //定义集合数组
                for(int i=0;i<arr.length();i++)
                {
                    HashMap<String,Object> map = new HashMap<String,Object>();   
                    JSONObject order = arr.getJSONObject(i);   //取得每一个订单
                    map.put("order_id", order.getInt("order_id"));
                    map.put("goods_name",order.getString("goods_name"));
                    map.put("amount", order.getDouble("amount"));
                    res.add(map);   //添加到集合数组
                }
                android.util.Log.i("orders",""+res);
                return res;   //提示返回的数据类型错误
            }
        }
        return null;
    }