简单的加几个JSON字符串累加之后，con_list.toString() 的结果 是：

 [{"id":5,"con":"请吃药****","repeatdelay":1,"time":"22:03:03","repeatday":"1,2,3,4,5,6","repeattimes":2}, {"id":6,"con":"请吃药****","repeatdelay":1,"time":"22:03:03","repeatday":"1,2,3,4,5,6","repeattimes":2}, {"id":7,"con":"请吃药****","repeatdelay":1,"time":"22:03:03","repeatday":"1,2,3,4,5,6","repeattimes":2}]

LinkedLIst<String> 可以自动将JSON字符串编排格式