如何使用Java中的Gson库将对象列表自动转换为JSONArray？
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How to convert automatically list of objects to JSONArray with Gson library in java?
提问by snaggs
Lets say I have following list of custom object: ArrayList<GroupItem>where GroupItemis some class that has intand Stringvariables.
可以说我有以下的自定义对象的名单：ArrayList<GroupItem>这里GroupItem是一些具有类int和String变量。
I tried so far Gsonlibrary but it's not exactly what I want.
到目前为止，我尝试过Gson图书馆，但这不是我想要的。
ArrayList<GroupItem> groupsList = /* ... */
Gson gson = new Gson();
JsonElement element = gson.toJsonTree(groupsList, new TypeToken<ArrayList<GroupItem>>() {}.getType());
JsonArray jsonArray = element.getAsJsonArray();
My goal is to get JSONArray(org.Json.JSONArray) somehow. Any ideas?
我的目标是以JSONArray某种方式获得(org.Json.JSONArray)。有任何想法吗？
[EDIT]
[编辑]
My project is Android with Cordova that has API based on org.Json.JSONArray
我的项目是带有 Cordova 的 Android，它具有基于 org.Json.JSONArray
ANd I thought to write some generic way to convert instances to JSONArray/ JSONObject
而且我想写一些通用的方法来将实例转换为JSONArray/JSONObject
Thanks,
谢谢，
采纳答案by snaggs
This way is worked for me:
这种方式对我有用：
Convert all list to String.
将所有列表转换为字符串。
String element = gson.toJson(
groupsList,
new TypeToken<ArrayList<GroupItem>>() {}.getType());
Create JSONArrayfrom String:
JSONArray从字符串创建：
JSONArray list = new JSONArray(element);
回答by jeremyjjbrown
Why do you want to use GSON to convert to an org.json class? Nor do you need to write any custom code to get a JSONArray. The org.json apiprovides a way to do it.
为什么要使用 GSON 转换为 org.json 类？您也不需要编写任何自定义代码来获取 JSONArray。该org.json API提供一种方式来做到这一点。
LinkedList list = new LinkedList();
list.add("foo");
list.add(new Integer(100));
list.add(new Double(1000.21));
list.add(new Boolean(true));
list.add(null);
JSONArray jsonArray = new JSONArray(list);
System.out.print(jsonArray);
回答by weston
You don't need gson. There's a constructorthat takes a collection, so just:
你不需要gson。有一个接受集合的构造函数，所以只需：
ArrayList<GroupItem> groupsList =... ;
JSONArray JSONArray = new JSONArray(groupsList);
回答by Brian Roach
The org.jsonbased classes included in Android don't have any features related to converting Java POJOs to/from JSON.
org.jsonAndroid 中包含的基础类没有任何与将 Java POJO 转换为 JSON 或从 JSON 转换相关的功能。
If you have a list of some class (List<GroupItem>) and you absolutely need to convert that to a org.json.JSONArrayyou have two choices:
如果您有某个类 ( List<GroupItem>)的列表并且您绝对需要将其转换为 aorg.json.JSONArray您有两个选择：
A) Use Gson or Hymanson to convert to JSON, then parse that JSON into a JSONArray:
A) 使用 Gson 或 Hymanson 转换为 JSON，然后将该 JSON 解析为JSONArray：
List<GroupItem> list = ...
String json = new Gson().toJson(list);
JSONArray array = new JSONArray(json);
B) Write code to create the JSONArrayand the JSONObjects it will contain from your Java objects:
B) 编写代码以从您的 Java 对象创建JSONArray和JSONObject它将包含的s：
JSONArray array = new JSONArray();
for (GroupItem gi : list)
{
JSONObject obj = new JSONObject();
obj.put("fieldName", gi.fieldName);
obj.put("fieldName2", gi.fieldName2);
array.put(obj);
}
回答by Ronald
Use Hymanson for JSON to Object or Object to JSON
使用 Hymanson for JSON to Object 或 Object to JSON
See the next link Hymanson examples
请参阅下一个链接Hyman逊示例
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.configure(SerializationFeature.INDENT_OUTPUT, true);
StringWriter stringWriter = new StringWriter();
objectMapper.writeValue(stringWriter, groupsList );
System.out.println("groupsList JSON is\n"+stringWrite);
