Gson change default Boolean Value to false if the field doesn't exist in json

Question

I have model like this

public class testModel {

    public boolean a = true;
    public Test2 test2 = new Test2();

    public class Test2 {
        public boolean b = true;
    }
}

and a json like this

{
"test2":{}
}

when i parse this json with Gson

testModel testModel = new Gson().fromJson("{ \"test2\":{}}", testModel.class);
    Log.e("test", testModel.a + " " + testModel.test2.b);

and the log is:

E/test: true false

testModel.a is 'true' but testmodel.test2.b is 'false' why Gson changed the default value of b while b is not exist in json? what is the difference between b and a?

is it a Gson bug?

check this link https://stackoverflow.com/questions/33435683/deserialize-with-gson-and-null-values — Lingeshwaran, Oct 11 '17 at 09:11
@SamuelRobert I just tested with 2.8.0 but i get a true and b false. i have same problem in a real project too. — faraz khonsari, Oct 11 '17 at 09:28
Seems clear enough.. Could be a bug.. Although I couldn't reproduce it. — Samuel Robert, Oct 11 '17 at 10:32
@SamuelRobert I asked my question in Gson Github . I wrote the answer here — faraz khonsari, Oct 14 '17 at 10:51

score 1 · Accepted Answer · answered Oct 12 '17 at 18:55

I asked my question in github https://github.com/google/gson/issues/1168 and a member answered correctly.

answer:

TestModel has a no-arg constructor while Test2 implicitly has one that takes an instance of TestModel. Mark Test2 as a static class and it will work.

Gson change default Boolean Value to false if the field doesn't exist in json

1 Answers1