英文:
De-serializing nested JSON to Java in Android Studio
问题
我正在尝试将此JSON反序列化为Java对象类Mural的数组，并在我的应用程序中的列表（Recycler View）中显示它们。以下是我所需数据的格式化JSON示例。
{
"records": [{
"recordid": "e6b10b2f7cadbe7caec9a0b36e9e7b570c3add50",
"fields": {
"auteur_s": "Dupa",
"photo": {
"id": "7cd8a2bc799826835057eaec21a28730"
},
"annee": "1994",
"coordonnees_geographiques": [50.8527886675,
4.34530735016],
"personnage_s": "Cubitus - Dommel"
},
},
...
]
}
我使用Okhttp进行请求，并且响应成功，因此我使用它构造了一个JSONObject。我遍历该对象中的"records"数组，因为我在其中找到了所有需要的数据。具有字符串或数组值的键可以正常工作，我可以将它们加载到我的应用程序的Recycler View中，但是当我想访问"photo"，即嵌套在另一个对象中的键值对时，我会收到JSONException org.json.JSONException: No value for photo，并且我的Recycler View返回为空。
以下是代码的示例：
private void fetchMurals(){
threadExecutor.execute(new Runnable() {
@Override
public void run() {
OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
.url("https://bruxellesdata.opendatasoft.com/api/records/1.0/search/?dataset=comic-book-route&rows=58")
.get()
.build();
try{
Response response = client.newCall(request).execute();
String json = response.body().string();
JSONObject jsonObject = new JSONObject(json);
JSONArray jsonRecordsArray = jsonObject.getJSONArray("records");
int arraySize = jsonRecordsArray.length();
muralArrayList = new ArrayList<>();
for (int i = 0; i < arraySize; i++){
String jsonID = jsonRecordsArray.getJSONObject(i).getString("recordid");
JSONObject jsonMural = jsonRecordsArray.getJSONObject(i).getJSONObject("fields");
JSONObject jsonMuralPhoto = jsonMural.getJSONObject("photo");
final Mural currentMural = new Mural(
jsonID,
(jsonMural.has("auteur_s")) ? jsonMural.getString("auteur_s") : "Unknown Author",
(jsonMuralPhoto.has("id")) ? jsonMuralPhoto.getString("id") : "No picture available!",
(jsonMural.has("personnage_s")) ? jsonMural.getString("personnage_s") : "Unknown character",
(jsonMural.has("annee")) ? jsonMural.getString("annee") : "Unknown year of creation",
new LatLng(jsonMural.getJSONArray("coordonnees_geographiques").getDouble(0),
jsonMural.getJSONArray("coordonnees_geographiques").getDouble(1))
);
muralArrayList.add(currentMural);
} catch (IOException e){
e.printStackTrace();
}
});
}
我尝试过很多此类变体，但迄今为止都没有成功。是否可能是循环的问题？或者是我正在调用的jsonMural.getJSONObject("photo")出现了问题？
英文:
I'm trying to deserialize this JSON to an array of Java objects of class Mural and show them in a list (Recycler View) in my app. Here's formatted example of the JSON with only the data that I need.
{
"records": [{
"recordid": "e6b10b2f7cadbe7caec9a0b36e9e7b570c3add50",
"fields": {
"auteur_s": "Dupa",
"photo": {
"id": "7cd8a2bc799826835057eaec21a28730",
},
"annee": "1994",
"coordonnees_geographiques": [50.8527886675,
4.34530735016],
"personnage_s": "Cubitus - Dommel"
},
},
...
]
}
I use Okhttp to make the request and the response is successful, so I use it to construct a JSONObject.
I traverse the "records" array in that object, because that's where I find all the data I need. Keys that have a string or an array as value work fine and I can load them into my app's Recycler View, but when I want to access "photo", i.e. a key:value pair nested within another object, I get a JSONException org.json.JSONException: No value for photo and my Recycler View returns empty.
Here's what the code looks like:
private void fetchMurals(){
threadExecutor.execute(new Runnable() {
@Override
public void run() {
OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
.url("https://bruxellesdata.opendatasoft.com/api/records/1.0/search/?dataset=comic-book-route&rows=58")
.get()
.build();
try{
Response response = client.newCall(request).execute();
String json = response.body().string();
JSONObject jsonObject = new JSONObject(json);
JSONArray jsonRecordsArray = jsonObject.getJSONArray("records");
int arraySize = jsonRecordsArray.length();
muralArrayList = new ArrayList<>();
for (int i = 0; i < arraySize; i++){
String jsonID = jsonRecordsArray.getJSONObject(i).getString("recordid");
JSONObject jsonMural = jsonRecordsArray.getJSONObject(i).getJSONObject("fields");
JSONObject jsonMuralPhoto = jsonMural.getJSONObject("photo");
final Mural currentMural = new Mural(
jsonID,
(jsonMural.has("auteur_s")) ? jsonMural.getString("auteur_s") : "Unknown Author",
(jsonMuralPhoto.has("id")) ? jsonMuralPhoto.getString("id") : "No picture available!",
(jsonMural.has("personnage_s")) ? jsonMural.getString("personnage_s") : "Unknown character",
(jsonMural.has("annee")) ? jsonMural.getString("annee") : "Unknown year of creation",
new LatLng(jsonMural.getJSONArray("coordonnees_geographiques").getDouble(0),
jsonMural.getJSONArray("coordonnees_geographiques").getDouble(1))
);
muralArrayList.add(currentMural);
} catch (IOException e){
e.printStackTrace();
}
});
}
I've tried many variations of this but none have worked so far. Could it be a problem with my loop? Or with the jsonMural.getJSONObject("photo") that I am calling?
答案1
得分: 0
我现在明白，我当时是在检查我的记录是否有字段"id"，而我应该检查它是否有"photo"。我在构造函数中将这一行代码更改为：
(jsonArtwork.has("photo")) ? jsonArtwork.getJSONObject("photo").getString("id") : "无可用图片！"
现在可以正常工作。
英文:
I see now that I was checking if my record had the field "id" whereas I should have been checking if it had "photo". I changed the line in my constructor to
(jsonArtwork.has("photo")) ? jsonArtwork.getJSONObject("photo").getString("id") : "No picture available!"
Works now.
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