Question

I’m using the Gson library in Java to serialize java objects to jSon and vice versa.

It works pretty well most of the times…but because I want to access my collections in javascript as mapped arrays I need to send them as properties and not json arrays.

For instance lets assume I have a Group which has several persons in it…if I send it:

var groups={"group1":[{"john":{"age":22,"sex":"male"}},{"patricia":{"age":32,"sex":"female"}}]}

I can’t do groups[“group1”][“john”]…and I’ll have to iterate through the array to find the correct person.

But if I do:

var groups={"group1":{"john":{"age":22,"sex":"male"},"patricia":{"age":32,"sex":"female"}}}

now I can do groups[“group1”][“john”].

The problem with this is that the Group has an Array of Person and when gson serializes to json it puts each person as an array element [{…and not as an property of group1 which in turn is a property of groups.

I’d like to know if it’s possible to tell gson to serialize to mapped arrays instead of normal arrays. If so how.

Answer 1

Don’t use an array if you don’t want an array.

If you change to using a Map in java it should serialize to your second example:

class ClassToSerialize {
    private HashMap<String, PersonInfo> group1 = new HashMap<String, PersonInfo>();
    ...
}

class PersonInfo {
    private int age;
    private String sex;
    ...
}

(The keys to the HashMap are your people’s names)