Question

我刚开始在Android中使用JSON，并且遇到了一些从JSON创建模型对象的问题。如果有人知道任何好的教程或资源，可以查看更多细节，我真的很感激他们。到目前为止，我一直在关注Vogella和Bignerdranch Android手册中的教程。

我可以拉入JSON并创建一个JSON对象，但是我的调查没有保存。

这是我要解析的JSON：

    [
        {
            "title": "Pepsi or Coke?",
            "id": 1,
            "questions": [
                {
                    "id": 1,
                    "title": "Which pop do you prefer?",
                    "single_response": true,
                    "answers": [
                        {
                            "title": "Pepsi",
                            "id": 1
                        },
                        {
                            "title": "Coke",
                            "id": 2
                        },
                        {
                            "title": "Mountain Dew",
                            "id": 3
                        }
                    ]
                },
                {
                    "id": 2,
                    "title": "What's your age?",
                    "single_response": true,
                    "answers": [
                        {
                            "title": "18-24",
                            "id": 4
                        },
                        {
                            "title": "25-34",
                            "id": 5
                        },
                        {
                            "title": "35-50",
                            "id": 6
                        },
                        {
                            "title": "50+",
                            "id": 7
                        }
                    ]
                },
                {
                    "id": 3,
                    "title": "What's your political association?",
                    "single_response": true,
                    "answers": [
                        {
                            "title": "Republican",
                            "id": 8
                        },
                        {
                            "title": "Democrat",
                            "id": 9
                        }
                    ]
                }
            ]
        }
    ]

我正在检索这样的json：

byte[] getUrlBytes(String urlSpec) throws IOException {
            URL url = new URL(urlSpec);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();

            try {
                ByteArrayOutputStream out = new ByteArrayOutputStream();
                InputStream in = connection.getInputStream();

                if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) {
                    return null;
                }

                int bytesRead = 0;
                byte[] buffer = new byte[1024];
                while ((bytesRead = in.read(buffer)) > 0) {
                    out.write(buffer, 0, bytesRead);
                }
                out.close();
                return out.toByteArray();
            } finally {
                connection.disconnect();
            }
        }

        public String getUrl(String urlSpec) throws IOException {
            return new String(getUrlBytes(urlSpec));
        }

这是我解析它的地方：

public ArrayList<Survey> getSurveys(String apiKey) throws JSONException {
    ArrayList<Survey> surveys = new ArrayList<Survey>();

    try {
        String url = Uri.parse(ENDPOINT).buildUpon().appendQueryParameter("auth_token", apiKey).build().toString();
        String jsonString = getUrl(url);
        Log.i(TAG, "Received json string: " + jsonString);

        try {
            JSONArray array = new JSONArray(jsonString);

            for (int i = 0; i < array.length(); i ++) {
                JSONObject object = array.getJSONObject(i);
                Log.i(TAG, "Object is: " + object.toString());
            }

            for (int i = 0; i < array.length(); i++) {
                Survey survey = new Survey(array.getJSONObject(i));
                surveys.add(survey);
                Log.i(TAG, "Survey is: " + survey.toString());
            }  
        } catch (Exception e) {
            Log.e(TAG, "Survey didn't save");
        }

    } catch (IOException ioe) {
        Log.e(TAG, "Failed to retrieve surveys: " + ioe);
    }
    return surveys; 
}

我假设问题出在我的创建调查方法本身，因为JSON对象是正确创建的，但是调查没有保存。知道我哪里错了吗？

public Survey(JSONObject json) throws JSONException {
        mId = UUID.fromString(json.getString("id"));
        if (json.has("title")) {
            mTitle = json.getString("title");
        }
}

一如既往，非常感谢任何帮助！

Answer 1

原来问题是我试图将在JSON中发送的int id转换为UUID。

只要数据类型匹配，就可以正确创建项目。

将JSON转换为模型对象Android

1 个答案: