Enum serializes to null when nothing matches (instead of throwing IOException)

> What steps will reproduce the problem?

1. Implement a POJO that has an enum
2. Attempt to deserialize the POJO using a bad string for the enum's value
3. See that the enum's value is set to null

> What is the expected output? What do you see instead?

I expect to see an exception (probably IOException?), but instead the value is 
initialized to null.

> What version of the product are you using? On what operating system?

GSON 2.3, Android 4.4.2

> Please provide any additional information below.

Here's the relevant part of TypeAdapters.EnumTypeAdapter

    public T read(JsonReader in) throws IOException {
      if (in.peek() == JsonToken.NULL) {
        in.nextNull();
        return null;
      }
      return nameToConstant.get(in.nextString());
    }

`nameToConstant.get()` gives null when nothing is found.

Original issue reported on code.google.com by [e-mail] on 12 Nov 2014 at 2:17

[inder123]

How about something like this:

@SerializedName(defaultValue = TrafficLight.RED) public enum TrafficLight { RED, ORANGE, GREEN }

// defaultValue will also allowed to be null // if this annotation is not present, enum maintains current behavior.

Comments @JakeWharton @swankjesse @joel-leitch?

[inder123]

You can always install your custom type adapter for your enum that enforces this. Gson isn’t going to support this, sorry.