Deserialize with gson and null values

Question

I am trying to deserialize my own class with a null value. But my code doesn\'t work.

My json:

{\"Text\":null,\"Code\":0,\"Title\":\"This is Sparta!\         


        

Answer 1

I had a similar problem (an exception thrown on null value) with the following POJO:

public class MyElement {
    private String something;
    private String somethingElse;
    private JsonObject subEntry; // this doesn't allow deserialization of `null`!
}

and this code:

parsedJson = gson.fromJson(json, MyElement.class)

when subEntry returned by the backend was null.

I fixed it by changing the type of subEntry from JsonObject to JsonElement which is a parent class of both JsonObject and JsonNull, to allow deserialization of null values.

public class MyElement {
    private String something;
    private String somethingElse;
    private JsonElement subEntry; // this allows deserialization of `null`
}

To later check for null at runtime, you'd do as follows:

if (parsedJson.subEntry instanceof JsonNull) {
    ...
} else {
    ...
}