Jackson: Serialize and deserialize enum values as integers

You can use setting

objectMapper.enable(SerializationFeature.WRITE_ENUMS_USING_INDEX);

See https://github.com/FasterXML/jackson-databind/blob/master/src/test/java/com/fasterxml/jackson/databind/ser/TestEnumSerialization.java for complete test cases

Thanks to tip at https://righele.it/2016/01/30/jackson-deserialization-from-json-to-java-enums/

Yet another way:

public enum State {

    @JsonProperty("0")
    OFF,

    @JsonProperty("1")
    ON,

    @JsonProperty("2")
    UNKNOWN
}

However, this will produce {"state" : "1"} instead of {"state" : 1} (string, not numeric). In most cases it's OK

It should work by specifying JsonValue mapper.

public enum State {
    OFF,
    ON,
    UNKNOWN;

    @JsonValue
    public int toValue() {
        return ordinal();
    }
}  

This works for deserialization also, as noted in Javadoc of @JsonValue annotation:

NOTE: when use for Java enums, one additional feature is that value returned by annotated method is also considered to be the value to deserialize from, not just JSON String to serialize as. This is possible since set of Enum values is constant and it is possible to define mapping, but can not be done in general for POJO types; as such, this is not used for POJO deserialization

You can use in this way

import com.fasterxml.jackson.annotation.JsonFormat;

@JsonFormat(shape = JsonFormat.Shape.NUMBER)
public enum State {
       OFF,
       ON,
       UNKNOWN
}