如何将Json对象附加到android中已有的Json文件中

My json file contains,

我的json文件包含,

{
  "appointments": [
    {
      "appointmentId": "app_001",
      "appointmentTitle": "Appointment Title1",
      "appointmentDate": "2017-11-25",
      "appointmentTime": "10:30",
      "appointmentStatus": "active",
      "appointmentType": "meeting",
      "reminder": {
        "type": "notification",
        "time": "10:15",
        "status": "off"
      },
      "appointmentDescription": "blablablablabla1"
    },
    {
      "appointmentId": "app_002",
      "appointmentTitle": "AppointmentTitle2",
      "appointmentDate": "2017-11-26",
      "appointmentTime": "09:00",
      "appointmentStatus": "done",
      "appointmentType": "exam",
      "reminder": {
        "type": "alarm",
        "time": "08:45",
        "status": "on"
      },
      "appointmentDescription": "blablablablabla2"
    }
  ]
}
{
  "app