Java Enum Accepted Values

Question

An enum data type is defined as an attribute of a class.

public class Foo {

  public enum Direction {

    NORTH("north"),
    EAST("east"),
    SOUTH("south");

    public final String label;

    private Direction(String label) {
      this.label = label;
    }

  }

  private Directory direction;
  ...
}

When I parse a Json data to match the class, I get an error

String "east": not one of the values accepted for Enum class: [NORTH, EAST, SOUTH, WEST]

This problem can be resolved by changing the enum data to all low case. If I want to use the Java enum data type convention, what is needed to resolve the problem?

Answer 1

If you are using Jackson to deserialise the Foo class, you could:

public class Foo {

  public enum Direction {

    NORTH("north"),
    EAST("east"),
    SOUTH("south");

    @JsonValue
    public final String label;

    private Direction(String label) {
      this.label = label;
    }

  }

  private Direction direction;
  // getter, setter for direction must exist
}

// then deserialise by:
ObjectMapper mapper = new ObjectMapper();
String json = "{\"direction\":\"north\"}";
Foo f = mapper.readValue(json, Foo.class);

This will result in a Foo object with a Direction.NORTH field.
For other possibilities when using Jackson check https://www.baeldung.com/jackson-serialize-enums