# Package com.fasterxml.jackson.core.type

package com.fasterxml.jackson.core.type
Contains classes needed for type introspection, mostly used by data binding functionality. Most of this functionality is needed to properly handled generic types, and to simplify and unify processing of things Jackson needs to determine how contained types (of `Collection` and `Map` classes) are to be handled.

With 2.9, an additional type (`WritableTypeId`) was added to help handling of type identifiers needed to support polymorphic type serialization, deserialization.

Related Packages
Package
Description
com.fasterxml.jackson.core
Main public API classes of the core streaming JSON processor: most importantly `JsonFactory` used for constructing JSON parser (`JsonParser`) and generator (`JsonGenerator`) instances.
Class
Description
ResolvedType
Type abstraction that represents Java type that has been resolved (i.e.
TypeReference<T>
This generic abstract class is used for obtaining full generics type information by sub-classing; it must be converted to `ResolvedType` implementation (implemented by `JavaType` from "databind" bundle) to be used.
WritableTypeId
This is a simple value class used between core streaming and higher level databinding to pass information about type ids to write.
WritableTypeId.Inclusion
Enumeration of values that matches enum `As` from annotation `JsonTypeInfo`: separate definition to avoid dependency between streaming core and annotations packages; also allows more flexibility in case new values needed at this level of internal API.