Jackson enum Serializing and DeSerializer

Note that as of this commit in June 2015 (Jackson 2.6.2 and above) you can now simply write:

public enum Event { @JsonProperty("forgot password") FORGOT_PASSWORD; } 

The behavior is documented here: https://fasterxml.github.io/jackson-annotations/javadoc/2.11/com/fasterxml/jackson/annotation/JsonProperty.html

Starting with Jackson 2.6 this annotation may also be used to change serialization of Enum like so:

 public enum MyEnum { @JsonProperty("theFirstValue") THE_FIRST_VALUE, @JsonProperty("another_value") ANOTHER_VALUE; } 

as an alternative to using JsonValue annotation.

You should create a static factory method which takes single argument and annotate it with @JsonCreator (available since Jackson 1.2)

@JsonCreator public static Event forValue(String value) { ... } 

Read more about JsonCreator annotation here.

Actual Answer:

The default deserializer for enums uses .name() to deserialize, so it's not using the @JsonValue. So as @OldCurmudgeon pointed out, you'd need to pass in {"event": "FORGOT_PASSWORD"} to match the .name() value.

An other option (assuming you want the write and read json values to be the same)...

More Info:

There is (yet) another way to manage the serialization and deserialization process with Jackson. You can specify these annotations to use your own custom serializer and deserializer:

@JsonSerialize(using = MySerializer.class) @JsonDeserialize(using = MyDeserializer.class) public final class MyClass { ... } 

Then you have to write MySerializer and MyDeserializer which look like this:

MySerializer

public final class MySerializer extends JsonSerializer<MyClass> { @Override public void serialize(final MyClass yourClassHere, final JsonGenerator gen, final SerializerProvider serializer) throws IOException, JsonProcessingException { // here you'd write data to the stream with gen.write...() methods } } 

MyDeserializer

public final class MyDeserializer extends org.codehaus.jackson.map.JsonDeserializer<MyClass> { @Override public MyClass deserialize(final JsonParser parser, final DeserializationContext context) throws IOException, JsonProcessingException { // then you'd do something like parser.getInt() or whatever to pull data off the parser return null; } } 

Last little bit, particularly for doing this to an enum JsonEnum that serializes with the method getYourValue(), your serializer and deserializer might look like this:

public void serialize(final JsonEnum enumValue, final JsonGenerator gen, final SerializerProvider serializer) throws IOException, JsonProcessingException { gen.writeString(enumValue.getYourValue()); } public JsonEnum deserialize(final JsonParser parser, final DeserializationContext context) throws IOException, JsonProcessingException { final String jsonValue = parser.getText(); for (final JsonEnum enumValue : JsonEnum.values()) { if (enumValue.getYourValue().equals(jsonValue)) { return enumValue; } } return null; } 

I've found a very nice and concise solution, especially useful when you cannot modify enum classes as it was in my case. Then you should provide a custom ObjectMapper with a certain feature enabled. Those features are available since Jackson 1.6. So you only need to write toString() method in your enum.

public class CustomObjectMapper extends ObjectMapper { @PostConstruct public void customConfiguration() { // Uses Enum.toString() for serialization of an Enum this.enable(WRITE_ENUMS_USING_TO_STRING); // Uses Enum.toString() for deserialization of an Enum this.enable(READ_ENUMS_USING_TO_STRING); } } 

There are more enum-related features available, see here:

https://github.com/FasterXML/jackson-databind/wiki/Serialization-Features https://github.com/FasterXML/jackson-databind/wiki/Deserialization-Features

I like the accepted answer. However, I would improve it a little (considering that there is now Java higher than version 6 available).

Example:

 public enum Operation { EQUAL("eq"), NOT_EQUAL("ne"), LESS_THAN("lt"), GREATER_THAN("gt"); private final String value; Operation(String value) { this.value = value; } @JsonValue public String getValue() { return value; } @JsonCreator public static Operation forValue(String value) { return Arrays.stream(Operation.values()) .filter(op -> op.getValue().equals(value)) .findFirst() .orElseThrow(); // depending on requirements: can be .orElse(null); } } 

Try this.

public enum Event { FORGOT_PASSWORD("forgot password"); private final String value; private Event(final String description) { this.value = description; } private Event() { this.value = this.name(); } @JsonValue final String value() { return this.value; } } 

You can customize the deserialization for any attribute.

Declare your deserialize class using the annotationJsonDeserialize (import com.fasterxml.jackson.databind.annotation.JsonDeserialize) for the attribute that will be processed. If this is an Enum:

@JsonDeserialize(using = MyEnumDeserialize.class) private MyEnum myEnum; 

This way your class will be used to deserialize the attribute. This is a full example:

public class MyEnumDeserialize extends JsonDeserializer<MyEnum> { @Override public MyEnum deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException { JsonNode node = jsonParser.getCodec().readTree(jsonParser); MyEnum type = null; try{ if(node.get("attr") != null){ type = MyEnum.get(Long.parseLong(node.get("attr").asText())); if (type != null) { return type; } } }catch(Exception e){ type = null; } return type; } } 

There are various approaches that you can take to accomplish deserialization of a JSON object to an enum. My favorite style is to make an inner class:

import com.fasterxml.jackson.annotation.JsonCreator; import com.fasterxml.jackson.annotation.JsonFormat; import com.fasterxml.jackson.annotation.JsonProperty; import org.hibernate.validator.constraints.NotEmpty; import java.util.Arrays; import java.util.Map; import java.util.function.Function; import java.util.stream.Collectors; import static com.fasterxml.jackson.annotation.JsonFormat.Shape.OBJECT; @JsonFormat(shape = OBJECT) public enum FinancialAccountSubAccountType { MAIN("Main"), MAIN_DISCOUNT("Main Discount"); private final static Map<String, FinancialAccountSubAccountType> ENUM_NAME_MAP; static { ENUM_NAME_MAP = Arrays.stream(FinancialAccountSubAccountType.values()) .collect(Collectors.toMap( Enum::name, Function.identity())); } private final String displayName; FinancialAccountSubAccountType(String displayName) { this.displayName = displayName; } @JsonCreator public static FinancialAccountSubAccountType fromJson(Request request) { return ENUM_NAME_MAP.get(request.getCode()); } @JsonProperty("name") public String getDisplayName() { return displayName; } private static class Request { @NotEmpty(message = "Financial account sub-account type code is required") private final String code; private final String displayName; @JsonCreator private Request(@JsonProperty("code") String code, @JsonProperty("name") String displayName) { this.code = code; this.displayName = displayName; } public String getCode() { return code; } @JsonProperty("name") public String getDisplayName() { return displayName; } } } 

In the context of an enum, using @JsonValue now (since 2.0) works for serialization and deserialization.

According to the jackson-annotations javadoc for @JsonValue:

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.

So having the Event enum annotated just as above works (for both serialization and deserialization) with jackson 2.0+.

Here is another example that uses string values instead of a map.

public enum Operator { EQUAL(new String[]{"=","==","==="}), NOT_EQUAL(new String[]{"!=","<>"}), LESS_THAN(new String[]{"<"}), LESS_THAN_EQUAL(new String[]{"<="}), GREATER_THAN(new String[]{">"}), GREATER_THAN_EQUAL(new String[]{">="}), EXISTS(new String[]{"not null", "exists"}), NOT_EXISTS(new String[]{"is null", "not exists"}), MATCH(new String[]{"match"}); private String[] value; Operator(String[] value) { this.value = value; } @JsonValue public String toStringOperator(){ return value[0]; } @JsonCreator public static Operator fromStringOperator(String stringOperator) { if(stringOperator != null) { for(Operator operator : Operator.values()) { for(String operatorString : operator.value) { if (stringOperator.equalsIgnoreCase(operatorString)) { return operator; } } } } return null; } } 

Besides using @JsonSerialize @JsonDeserialize, you can also use SerializationFeature and DeserializationFeature (jackson binding) in the object mapper.

Such as DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE, which give default enum type if the one provided is not defined in the enum class.

In my case, this is what resolved:

import com.fasterxml.jackson.annotation.JsonCreator; import com.fasterxml.jackson.annotation.JsonFormat; import com.fasterxml.jackson.annotation.JsonProperty; @JsonFormat(shape = JsonFormat.Shape.OBJECT) public enum PeriodEnum { DAILY(1), WEEKLY(2), ; private final int id; PeriodEnum(int id) { this.id = id; } public int getId() { return id; } public String getName() { return this.name(); } @JsonCreator public static PeriodEnum fromJson(@JsonProperty("name") String name) { return valueOf(name); } } 

Serializes and deserializes the following json:

{ "id": 2, "name": "WEEKLY" } 

I hope it helps!

I did it like this :

// Your JSON {"event":"forgot password"} // Your class to map public class LoggingDto { @JsonProperty(value = "event") private FooEnum logType; } //Your enum public enum FooEnum { DATA_LOG ("Dummy 1"), DATA2_LOG ("Dummy 2"), DATA3_LOG ("forgot password"), DATA4_LOG ("Dummy 4"), DATA5_LOG ("Dummy 5"), UNKNOWN (""); private String fullName; FooEnum(String fullName) { this.fullName = fullName; } public String getFullName() { return fullName; } @JsonCreator public static FooEnum getLogTypeFromFullName(String fullName) { for (FooEnum logType : FooEnum.values()) { if (logType.fullName.equals(fullName)) { return logType; } } return UNKNOWN; } } 

So the value of the property "logType" for class LoggingDto will be DATA3_LOG

@JsonFormat(shape = JsonFormat.Shape.OBJECT) public enum LoginOptionType { PHONE(1, "Phone"), MAIL(2, "mail"), PERSONAL_EMAIL(3, "Personal email"); private static List<LoginOptionType> all; static { all = new ArrayList<LoginOptionType>() { { add(LoginOptionType.PHONE); add(LoginOptionType.MAIL); add(LoginOptionType.PERSONAL_EMAIL); } }; } private final Integer viewValue; private final String name; LoginOptionType(Integer viewValue, String name) { this.viewValue = viewValue; this.name = name; } public Integer getViewValue() { return viewValue; } public String getName() { return name; } public static List<LoginOptionType> getAll() { return all; } } 

Response

[ { "viewValue": 1, "name": "Phone" }, { "viewValue": 2, "name": "mail" }, { "viewValue": 3, "name": "Personal email" } ] 

Here, 'value' acts as a deserialiser and 'namespace' acts as a serialiser. Hence, you can pass in value "Student Absent" to API while saving, and in DB it will be saved as "STUDENT_ABSENT". On the other hand, while retrieving data in your class, your API will return "Student Absent"

import com.fasterxml.jackson.annotation.JsonProperty; public enum AttendanceEnums { STUDENT_PRESENT, @JsonProperty(value = "Student Absent", namespace = "Student Absent") STUDENT_ABSENT; } 

I had been looking for a solution to enum serialization and I finally made a solution.

https://github.com/sirgilligan/EnumerationSerialization

https://digerati-illuminatus.blogspot.com/2022/10/java-enum-generic-serializer-and.html

It uses a new annotation and two new classes, EnumerationSerializer and EnumerationDeserializer. You can subclass the EnumerationDeserializer and make a class that sets the enum Class (typical approach) or you can annotate the enum and you don't have to have a subclass of EnumerationDeserializer.

@JsonSerialize(using = EnumerationSerializer.class) @JsonDeserialize(using = EnumerationDeserializer.class) @EnumJson(serializeProjection = Projection.NAME, deserializationClass = RGB.class) enum RGB { RED, GREEN, BLUE } 

Notice how the implementation of ContextualDeserializer pulls the class from the annotation.

https://github.com/sirgilligan/EnumerationSerialization/blob/main/src/main/java/org/example/EnumerationDeserializer.java

There is a lot of good code in this that might give insights.

For your specific question you could do this:

@JsonSerialize(using = EnumerationSerializer.class) @JsonDeserialize(using = EnumerationDeserializer.class) @EnumJson(serializeProjection = Projection.NAME, deserializationClass = Event.class) public enum Event { FORGOT_PASSWORD("forgot password"); //This annotation is optional because the code looks for value or alias. @EnumJson(serializeProjection = Projection.VALUE) private final String value; private Event(final String description) { this.value = description; } } 

Or you could do this:

@JsonSerialize(using = EnumerationSerializer.class) @JsonDeserialize(using = EnumerationDeserializer.class) @EnumJson(serializeProjection = Projection.NAME, deserializationClass = Event.class) public enum Event { FORGOT_PASSWORD("forgot password"); private final String value; private Event(final String description) { this.value = description; } } 

That's all you have to do.

Then if you have a class that "has a" event you can annotate each occurance to serialize the way you want.

class EventHolder { @EnumJson(serializeProjection = Projection.NAME) Event someEvent; @EnumJson(serializeProjection = Projection.ORDINAL) Event someOtherEvent; @EnumJson(serializeProjection = Projection.VALUE) Event yetAnotherEvent; } 

The simplest way I found is using @JsonFormat.Shape.OBJECT annotation for the enum.

@JsonFormat(shape = JsonFormat.Shape.OBJECT) public enum MyEnum{ .... } 

This post is old, but if it can help someone, use JsonFormat.Shape.STRING

@JsonFormat(shape = JsonFormat.Shape.STRING) public enum SomeEnum{ @JsonProperty("SOME_PROPERTY") someProperty, ... } 

Code results is like this

{"someenum":"SOME_PROPERTY"}