Gson：Bean中的枚举序列化问题

Question

My SegmentCreateRequest bean class:

public class SegmentCreateRequest {

    @SerializedName("name")
    private String segmentName;

    private SegmentSource segmentSource;

    public String getSegmentName() {
        return segmentName;
    }

    public void setSegmentName(String segmentName) {
        this.segmentName = segmentName;
    }

    public SegmentSource getSegmentSource() {
        return segmentSource;
    }

    public void setSegmentSource(SegmentSource segmentSource) {
        this.segmentSource = segmentSource;
    }

    public enum SegmentSource {

        @SerializedName("followed") FOLLOWED,
        @SerializedName("impressed") IMPRESSED,
        @SerializedName("engaged") ENGAGED,
        @SerializedName("tailored") TAILORED;

        @SerializedName("user_ids")
        private List<String> userIds;

        SegmentSource(){
            this.userIds = Lists.newArrayList();
        }

        public void setUserIds(List<String> userIds) {
            this.userIds = userIds;
        }

        public List<String> getUserIds() {
            return this.userIds;
        }

        public SegmentSource userIds(List<String> userIds) {
            this.userIds = userIds;
            return this;
        }
    }
}

The segmentSource field name should change according to the value of the enum.

I was expecting object serialization of this class to return something like:

{
 "name":"segment101",
 "followed":{"user_ids":["1234567890"]}
}

However, it returns:

{"name":"skumar-3020-seg","segmentSource":"followed"}

using Google Gson for serialization/deserialization.

How do I setup my bean to achieve the required serialization?

Answer 1

You are serializing an enum instance into a field named segmentSource .

The name of that field is not name!

Beyond that, there is also a potential bug in your code: enums are singeltons! There will be one instance of FOLLOWED for example. This means: any change to the list of FOLLOWED is visible "globally". There is no such thing as having two different SegmentCreateRequests then (in parallel).

In other words: when you create some

SegmentCreateRequests reqA = ... 

with some specific users on FOLLOWED; but you do

SegmentCreateRequests reqB = ... 

in parallel, then those two requests objects will be working on the same list in the end. Meaning: your code isn't thread safe. Thus: that list of users must not go into the enum constant. It should rather be a property of the surrounding request!