change field name to lowercase while deserializing POJO to JSON using GSON?

Question

I have a POJO class like this. I am deserializing my JSON to below POJO first..

public class Segment implements Serializable {
  @SerializedName("Segment_ID")
  @Expose
  private String segmentID;
  @SerializedName("Status")
  @Expose
  private String status;
  @SerializedName("DateTime")
  @Expose
  private String dateTime;
  private final static long serialVersionUID = -1607283459113364249L;

  ...
  ...
  ...

  // constructors
  // setters
  // getters
  // toString method
}

Now I am serializing my POJO to a JSON like this using Gson and it works fine:

Gson gson = new GsonBuilder().create();
String json = gson.toJson(user.getSegments());
System.out.println(json);

I get my json printed like this which is good:

[{"Segment_ID":"543211","Status":"1","DateTime":"TueDec2618:47:09UTC2017"},{"Segment_ID":"9998877","Status":"1","DateTime":"TueDec2618:47:09UTC2017"},{"Segment_ID":"121332121","Status":"1","DateTime":"TueDec2618:47:09UTC2017"}]

Now is there any way I can convert "Segment_ID" to all lowercase while deserializing? I mean "Segment_ID" should be "segment_id" and "Status" should be "status". Is this possible to do using gson? So it should print like this instead.

[{"segment_id":"543211","status":"1","datetime":"TueDec2618:47:09UTC2017"},{"segment_id":"9998877","status":"1","datetime":"TueDec2618:47:09UTC2017"},{"segment_id":"121332121","status":"1","datetime":"TueDec2618:47:09UTC2017"}]

if I change the "SerializedName" then while deserializing my JSON to POJO, it doesn't work so not sure if there is any other way.

Answer 1

You need to provide alternative names for deserialisation process and primary ( value property) for serialisation.

class Segment {

    @SerializedName(value = "segment_id", alternate = {"Segment_ID"})
    @Expose
    private String segmentID;

    @SerializedName(value = "status", alternate = {"Status"})
    @Expose
    private String status;

    @SerializedName(value = "datetime", alternate = {"DateTime"})
    @Expose
    private String dateTime;

}

Now, you can deserialise fields: Segment_ID , DateTime , Status and still be able to serialise as desired.