Can I use Gson to serialize method-local classes and anonymous classes?
gson, java
Solution
FWIW, Jackson will serialize anonymous and local classes just fine.
public static void main(String[] args) throws Exception
{
ObjectMapper mapper = new ObjectMapper();
class MethodLocal {public String key = "method local";}
System.out.println(mapper.writeValueAsString(new MethodLocal()));
// {"key":"method local"}
Object extendsObject = new Object() {public String key = "extends Object";};
System.out.println(mapper.writeValueAsString(extendsObject));
// {"key":"extends Object"}
}
Note that Jackson by default won't access non-public fields through reflection, as Gson does, but it could be configured to do so. The Jackson way is to use regular Java properties (through get/set methods), instead. (Configuring it to use private fields does slow down the runtime performance, a bit, but it's still way faster than Gson.)
Problem
Example: ``` import com.google.gson.Gson; class GsonDemo { private static class Static {String key = "static";} private class NotStatic {String key = "not static";} void testGson() { Gson gson = new Gson(); System.out.println(gson.toJson(new Static())); // expected = actual: {"key":"static"} System.out.println(gson.toJson(new NotStatic())); // expected = actual: {"key":"not static"} class MethodLocal {String key = "method local";} System.out.println(gson.toJson(new MethodLocal())); // expected: {"key":"method local"} // actual: null (be aware: the String "null") Object extendsObject = new Object() {String key = "extends Object";}; System.out.println(gson.toJson(extendsObject)); // expected: {"key":"extends Object"} // actual: null (be aware: the String "null") } public static void main(String... arguments) { new GsonDemo().testGson(); } } ``` I would like these serializations especially in unit tests. Is there a way to do so? I found Serializing anonymous classes with Gson, but the argumentation is only valid for de-serialization.