datatypes

Jackson module that adds supports for JDK datatypes included in version 8 which can not be directly supported by core databind due to baseline being JDK 6, excluding following:

• New Date/Time datatypes (supported by jackson-datatype-jsr310 module)
• Support for parameter names (supported by jackson-module-parameter-names)

NOTE: only available for Jackson 2.x; functionality included in jackson-databind itself for Jackson 3.x.

Usage

Maven dependency

To use module on Maven-based projects, use following dependency:

<dependency>
  <groupId>com.fasterxml.jackson.datatype</groupId>
  <artifactId>jackson-datatype-jdk8</artifactId>
  <version>2.12.2</version>
</dependency>    

(or whatever version is most up-to-date at the moment)

Registering module

Like all standard Jackson modules (libraries that implement Module interface), registration is done as follows:

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new Jdk8Module());
// Or, the more fluent version: ObjectMapper mapper = new ObjectMapper().registerModule(new Jdk8Module());

after which functionality is available for all normal Jackson operations: you can read JSON into supported JDK8 types, as well as write values of such types as JSON, so that for example:

class Contact {
    private final String name;
    private final Optional<String> email;

    public Contact(String name, Optional<String> email) {
        this.name = name;
        this.email = email;
    }

    public String getName() {
        return name;
    }

    public Optional<String> getEmail() {
        return email;
    }
}

...

Contact nullEmail = new Contact("Example Co.", null);
String nullEmailJson = mapper.writeValueAsString(nullEmail);
// prints: {"name":"Example Co.","email":null}
System.out.println(nullEmailJson);

Contact emptyEmail = new Contact("Example Co.", Optional.empty());
String emptyEmailJson = mapper.writeValueAsString(emptyEmail);
// prints: {"name":"Example Co.","email":null}
System.out.println(emptyEmailJson);

Contact withEmail = new Contact("Example Co.", Optional.of("[email protected]"));
String withEmailJson = mapper.writeValueAsString(withEmail);
// prints:  {"name":"Example Co.","email":"[email protected]"}
System.out.println(withEmailJson);