Can Jackson/Gson give me all known deserializable field names?

Question

If I have a POJO:

public class Item {

  @JsonProperty("itemName")
  public String name;
  private int quantity;

  @JsonGetter("quantity") //call it "quantity" when serializing
  public int getQuantity() {...}

  @JsonSetter("number") //call it "number" when deserializing
  public void setQuantity() {...}
}

or the same with Gson annotations:

public class Item {

  @SerializedName("itemName")
  public String name;

  @SerializedName("number")
  private int quantity;

  ...
}

Is there a way to use Jackson/Gson to get all field names that it would know how to deserialize (itemName and number in this case)?

Answer 1

This is for Jackson:

public static List<String> getDeserializationProperties(Class<?> beanType)
{
    ObjectMapper mapper = new ObjectMapper();
    JavaType type = mapper.getTypeFactory().constructType(beanType);
    BeanDescription desc = mapper.getSerializationConfig().introspect(type);
    return desc.findProperties().stream()
            .filter(def -> def.couldDeserialize())
            .map(def -> def.getName())
            .collect(Collectors.toList());
}

Calling:

System.out.println(getDeserializationProperties(Item.class));

Output:

[itemName, number]