Question

我正在尝试从字符串中读取JSON（从Web获取），但它返回null。

具体来说，result.append(name + id);给了我nullnull

JSONParser parser = new JSONParser();
try {
    Object obj = parser.parse(datJ);
    JSONObject jsonObject = (JSONObject) obj;
    String name = (String) jsonObject.get("name");
    Integer id = (Integer) jsonObject.get("id");
    result.append(name + id);

} catch (MalformedURLException e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
} catch (IOException e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
} catch (org.json.simple.parser.ParseException e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
}

考虑datJ包含以下JSON字符串：

{
    "rikeard":{
        "id":2828822,
        "name":"Rikeard",
        "profileIconId":688,
        "summonerLevel":30,
        "revisionDate":1422917445000
    }
}

编辑：最终代码正常工作

JSONParser parser = new JSONParser();
        try {
            String datJ = IOUtils.toString(new URL(url));
             Object obj = parser.parse(datJ);
                JSONObject rikeardObject = (JSONObject) ((Map<?, ?>) obj).get("rikeard");
                String name = (String) rikeardObject.get("name");
                Long id = (Long) rikeardObject.get("id");

特别感谢Sufian和Ved！

Answer 1

试试这个：

JSONParser parser = new JSONParser();
try {
      Object obj = parser.parse(datJ);
      JSONObject jsonObject = (JSONObject) obj;

        JSONObject rikeardObject = (JSONObject) jsonObject.get("rikeard");;
        String name = (String) rikeardObject .get("name");
        Integer id = (Integer) rikeardObject .get("id");
        result.append(name + id);
    } catch (MalformedURLException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    } catch (IOException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    } catch (org.json.simple.parser.ParseException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }

Answer 2

使用这种方法对我有用，

    private void extractJson(){
    String jsonString="{\"rikeard\":{\"id\":2828822,\"name\":\"Rikeard\",\"profileIconId\":688,\"summonerLevel\":30,\"revisionDate\":1422917445000}}";

    try {
        JSONObject jsonObject=new JSONObject(jsonString);
        if(jsonObject!=null){
            jsonObject=jsonObject.optJSONObject("rikeard");
            if(jsonObject!=null){
                String id=jsonObject.optString("id");
                Log.d("MainActivity","id="+id);
            }
        }


    } catch (JSONException e) {
        e.printStackTrace();
    }
}

Answer 3

“id”和“name”在JSON对象内部，对着“rikeard”键。因此，您需要进行如下更改：

JSONParser parser = new JSONParser();
try {
    Object obj = parser.parse(datJ);
    JSONObject jsonObject = (JSONObject) obj;
    JSONObject rikeardObject = (JSONObject) obj.get("rikeard");
    String name = (String) rikeardObject.get("name");
    Integer id = (Integer) rikeardObject.get("id");
    result.append(name + id);

} catch (MalformedURLException e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
} catch (IOException e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
} catch (org.json.simple.parser.ParseException e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
}

Json对象对给定键返回null

3 个答案: