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javaandroidjsonretrofitpojo

Dynamic Json Response mapping to Pojo

I am using an API which returns a dynamic amount of JSON keys for a given response (let's say the minimum is 20 and the maximum 30 keys). I know all possible keys in advance, I just don't know how many will be returned for a given response.

How do I map those fields to a POJO that has the maximum amount of fields (30) with all missing fields being null. So if the response contains 20 keys, I would like the POJO to populate all its fields with the corresponding values from the JSON while the other 10 fields in the POJO remain null.

Currently I am using Retrofit and GSON, but I'll be glad to change if I find a way to do this with other libraries.

Solution

  • Using jackason

    import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

...

static class Data {
    public String k1;
    public String k2;
    public String k3;
    // ...
    public String kN;
}

public static void main(String[] args) throws JsonProcessingException {
    Data data = new ObjectMapper().readValue("{\"k2\": \"value2\"}", Data.class);
    System.out.printf("%s, %s, %s, ...%n", data.k1, data.k2, data.k3);
}

    with output

    null, value2, null, ...