Gson().fromJson returns null in Android

Question

I'm trying to deserialize an error message I get from an api, this is my string:

{"Message":"Ya existe un usuario registrado con ese email"}

But when I call Gson like this it returns a NetworkError with null values:

String message = new Gson().fromJson(jsonMessage, NetworkError.class).getMessage();

I have been looking at similar questions and realize there has to be something wrong in the NetworkError class but I can't figure out what it is. Here is the class:

public class NetworkError {

    private String message;

    public NetworkError(final String message) {
        this.message = message;
    }

    public String getMessage() { return message; }
}

I have tried by including a set method and an empty constructor but I still got null. Thanks

score 4 · Accepted Answer · edited May 23 '17 at 12:17

4

Inside NetworkError.java class, try changing your message variable in the class to Message, since that is the key you are receiving in the REST response and it might be causing issues when mapping the key.

I can understand that you still might want to use camel case for your variable names. You can use @SerializedName annotation to keep your variable name anything you want but still have GSON map to it. You can read more on what is the basic purpose of @SerializedName annotation in android using GSon

edited May 23 '17 at 12:17

Community

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1

answered Apr 30 '17 at 14:42

Shobhit Puri

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Thanks for the answer and the tip about using the annotation – moondaisy Apr 30 '17 at 14:56

score 2 · Answer 2 · answered Apr 30 '17 at 14:53

2

Keys in JSON are case sensitive. Therefore, Gson is looking for the "message" key, which is not there (you are using the "Message" key).

You can just do:

@SerializedName("Message")
private String message;

answered Apr 30 '17 at 14:53

Mikel Pascual

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Gson().fromJson returns null in Android

2 Answers2