使用GSON序列化对象

Question

How can I serialize and deserialize this object with gson to json:

public class test{

@Expose
public List< Pair<Double,Double> > list;

@Expose
public int alpha;
}

I've tried this:

Gson gson = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create();
String str = gson.toJson(testInstance,test.class);

where testInstance is an instance of class test, but it's not working because of Pair structure in List.

Answer 1

You have configured Gson object using excludeFieldsWithoutExposeAnnotation method. From documentation :

Configures Gson to exclude all fields from consideration for serialization or deserialization that do not have the Expose annotation.

Could you change Pair class? If yes, you have to add @Expose annotation to each property which you want serialize to JSON. If no, you can create similar class in your program and add annotations.

Answer 2

if the object is of a generic type, then the Generic type information is lost because of Java Type Erasure . You can solve this problem by specifying the correct parameterized type for your generic type. Try parameterized type like List<String> . This should work