You don’t need to switch to Jackson. Gson 2.1 introduced a new TypeAdapter interface that permits mixed tree and streaming serialization and deserialization. The API is efficient and flexible. See Gson’s Streaming doc for an example of combining tree and binding modes. This is strictly better than mixed streaming and tree modes; with binding you … Read more
I’d take a slightly different approach as follows, so as to minimize “manual” parsing in my code, as unnecessarily doing otherwise somewhat defeats the purpose of why I’d use an API like Gson in the first place. // output: // [User: id=1, name=Jonas, updateDate=2011-03-24 03:35:00.226] // [User: id=5, name=Test, updateDate=2011-05-07 08:31:38.024] // using java.sql.Timestamp public … Read more
Since Gson 2.8.0, you can use TypeToken#getParameterized(Type rawType, Type… typeArguments) to create the TypeToken, then getType() should do the trick. For example: TypeToken.getParameterized(ArrayList.class, myClass).getType()
Any fields you don’t want serialized in general you should use the “transient” modifier, and this also applies to json serializers (at least it does to a few that I have used, including gson). If you don’t want name to show up in the serialized json give it a transient keyword, eg: private transient String … Read more
Method to deserialize generic collection: import java.lang.reflect.Type; import com.google.gson.reflect.TypeToken; … Type listType = new TypeToken<ArrayList<YourClass>>(){}.getType(); List<YourClass> yourClassList = new Gson().fromJson(jsonArray, listType); Since several people in the comments have mentioned it, here’s an explanation of how the TypeToken class is being used. The construction new TypeToken<…>() {}.getType() captures a compile-time type (between the < and >) … Read more
Here you go: import java.lang.reflect.Type; import com.google.gson.reflect.TypeToken; Type type = new TypeToken<Map<String, String>>(){}.getType(); Map<String, String> myMap = gson.fromJson(“{‘k1′:’apple’,’k2′:’orange’}”, type);
This is simple code to do it, I avoided all checks but this is the main idea. public String parse(String jsonLine) { JsonElement jelement = new JsonParser().parse(jsonLine); JsonObject jobject = jelement.getAsJsonObject(); jobject = jobject.getAsJsonObject(“data”); JsonArray jarray = jobject.getAsJsonArray(“translations”); jobject = jarray.get(0).getAsJsonObject(); String result = jobject.get(“translatedText”).getAsString(); return result; } To make the use more generic – … Read more
The problem is you’re telling Gson you have an object of your type. You don’t. You have an array of objects of your type. You can’t just try and cast the result like that and expect it to magically work 😉 The User guide for Gson Explains how to deal with this: https://github.com/google/gson/blob/master/UserGuide.md This will … Read more
Even without seeing your JSON string you can tell from the error message that it is not the correct structure to be parsed into an instance of your class. Gson is expecting your JSON string to begin with an object opening brace. e.g. { But the string you have passed to it starts with an … Read more
As the exception message states Caused by: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 16 path $.nestedPojo while deserializing, Gson was expecting a JSON object, but found a JSON array. Since it couldn’t convert from one to the other, it threw this exception. The JSON format is described here. In short, it … Read more