Question

我刚刚开始使用android开发，我遇到了一个我无法解决的问题。

我使用Volley在我的Android应用中调用了一个API，我得到以下响应：

 [
  {
    "id": 25,
    "user_id": 39,
    "positionX": "51.4595484",
    "positionY": "5.4757402",
    "modified": "2016-12-15T00:00:00"
  },
  {
    "id": 26,
    "user_id": 40,
    "positionX": "51.4595518",
    "positionY": "5.4757409",
    "modified": "2016-12-15T00:00:00"
  },
  {
    "id": 27,
    "user_id": 41,
    "positionX": "51.459554",
    "positionY": "5.4757413",
    "modified": "2016-12-15T00:00:00"
  },
  {
    "id": 28,
    "user_id": 42,
    "positionX": "51.459554",
    "positionY": "5.4757413",
    "modified": "2016-12-15T00:00:00"
  }
]

我正在尝试从JSONArray获取数据，但我无法使其正常工作......这是我的代码：

@Override
public void onResponse(String response) {
    try {
        JSONArray jsonArray = new JSONArray(response);
        JSONObject jsonObject = jsonArray.getJSONObject(0);

        for (int i = 0; i < jsonObject.length(); i++) {
            JSONObject row = jsonObject.getJSONObject();
            points.add(new LatLng(row.getDouble("positionX"),row.getDouble("positionY")));
        }
        Toast.makeText(getApplicationContext(), "Updated users info." + points.get(0).toString(), Toast.LENGTH_LONG).show();
    } catch (JSONException e) {
        Toast.makeText(getApplicationContext(), "error" + e.getMessage(), Toast.LENGTH_LONG).show();
    }
}

Answer 1

您只需从row而不是第一个JSONArray对象获取JSON，只需执行此操作

1。）创建JSONAray

2.。）使用索引

遍历数组并获取JSONObject

3.。）从第二步中检索到的JSONObject中获取数据

    JSONArray jsonArray = new JSONArray(response);

    for (int i = 0; i < jsonArray.length(); i++) {
         JSONObject row = jsonArray.getJSONObject(i);
         points.add(new LatLng(row.getDouble("positionX"),row.getDouble("positionY")));
        }

改进：为避免丢失密钥和值的异常，请使用optDouble来处理字符串形式的缺失值或值

Answer 2

试试这个

@Override
                    public void onResponse(String response) {
                        try {
                            JSONArray jsonArray = new JSONArray(response);

                            for (int i = 0; i < jsonArray.length(); i++) {
                                JSONObject row= jsonArray.getJSONObject(i)                               
                                points.add(new LatLng(row.getDouble("positionX"),row.getDouble("positionY")));
                            }
                            Toast.makeText(getApplicationContext(), "Updated users info." + points.get(0).toString(), Toast.LENGTH_LONG).show();
                        } catch (JSONException e) {
                            Toast.makeText(getApplicationContext(), "error" + e.getMessage(), Toast.LENGTH_LONG).show();
                        }
                    }

但我建议您使用 Gson Library 来解析json，这是最好的商业

下载 - http://www.java2s.com/Code/Jar/g/Downloadgson222jar.htm

如何添加lib- Android Studio: Add jar as library?

如何使用它 - https://blog.ajduke.in/2013/07/28/getting-started-with-google-gson/或https://sites.google.com/site/gson/gson-user-guide#TOC-Primitives-Examples

把字符串转换成json

2 个答案: