Question

我需要从Java中的JSON文件中读取股票价值

 {"name":"UCG.MI", "history":
    {"2019-05-16":{"op":"1","cl":"2","h":"2","lo":"1","vol":"10"},
     "2019-05-15":{"op":"1","cl":"2","h":"2","lo":"1","vol":"10"},
     "2019-05-14":{"op":"1","cl":"2","h":"2","lo":"1","vol":"10"},
     "2019-05-13":{"op":"1","cl":"2","h":"2","lo":"1","vol":"10"},
     "2000-01-04":{"op":"1","cl":"2","h":"2","lo":"1","vol":"10"},
     "2000-01-03":{"op":"1","cl":"2","h":"2","lo":"1","vol":"10"}
    }
}

我可以使用org.json来获取“名称”

json = new String(Files.readAllBytes(Paths.get("UCG.json")), "UTF-8");

 JSONObject obj = new JSONObject(json);

 String pageName = obj.getString("name");

 System.out.println(pageName);

有人可以帮助我阅读文件的其余部分吗？

我尝试

JSONArray arr = obj.getJSONArray("history");

for (int i = 0; i < arr.length(); i++) {

    String post_id = arr.getJSONObject(i).getString("op");

}

但是我会犯错误

org.json.JSONException：JSONObject [“ history”]不是JSONArray。

预先感谢

Answer 1

您会收到错误消息，因为JSON中的history属性不是数组而是对象。请尝试以下部分，而不是已有的

JSONObject history = obj.getJSONObject("history");
for (String date: history.keySet()) {
  JSONObject post = history.getJSONObject(date);
  String postId = post.getString("op");
  // ...
}

Answer 2

首先，历史记录是一个JSON对象。其次，“历史记录”包含一个具有六个Key（String）-Value（JSONObject）对的对象。

上面的逻辑在这里实现。

    JSONObject history = (JSONObject) jsonObject.get("history");
    Set<String> dates = history.keySet();

    for(String date:dates)
    {
        JSONObject details = (JSONObject) history.get(date);
        System.out.println(details.get("op"));
    }

注意：我在这里使用了json-simple java库。

Java中json文件的股票价格

2 个答案: