Android Gson - deserializing null vs absent values

Question

I'd like to understand the difference with a server returning value verses that value being completely absent in the response.

lets take at what i have so far:

data class MyApiResponse(@SerializedName("name") val name: String,
                                  @SerializedName("address") val address: String,
                                  @SerializedName("max_time") val maxTime: Double? = null //this field  might  BE  COMPLETELY absent in response, what will  happen  here ? 
)

regarding the maxTime value, if the value is COMPLETELY absent from server response, will the app crash or will the value be null ?

the issue is im trying to distinguish between server sending

max_time: null vs it being completely absent ,how does gson handle this ?

I think it will just be null, I have a similar setup in my project where some fields are just sometimes not sent. They come as null in my POJOs. I use Java but it should be the same. Do you need to differentiate between those two states (do a different thing for null vs absent) or is it just a theoretical question? — Vucko, Oct 04 '19 at 06:51
i dont need to do anything different. i just want to know if app will crash if value is ABSENT. — j2emanue, Oct 04 '19 at 06:52
It will be null in absence of the value ,and can you do try catch block? that will be great. — raj kavadia, Oct 04 '19 at 07:02

score 1 · Accepted Answer · answered Oct 04 '19 at 07:12

1

In both cases it will be null. Might look here for more info: Gson optional and required fields

answered Oct 04 '19 at 07:12

r2rek

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score 0 · Answer 2 · answered Oct 04 '19 at 07:25

Please try this solution:

    String json = ""; //Your json has a String
    JsonObject jsonObject = new JsonParser().parse(json).getAsJsonObject();


    String name = jsonObject.get("name").toString();
    String adress = jsonObject.get("address").toString();
    //If null, use a default value
    JsonElement max_time = jsonObject.get("max_time");
    String text = (max_time instanceof JsonNull) ? "" : max_time.getAsString();




    String json = ""; //Your json has a String
    Gson gson = new GsonBuilder().serializeNulls().create();
    MyApiResponse myApiResponse = gson.fromJson(json, YOURCLASSNAME.class);

Android Gson - deserializing null vs absent values

2 Answers2