JavaType
Date: 2016-12-04

com.fasterxml.jackson.databind

## Class JavaType

- java.lang.Object
- - com.fasterxml.jackson.core.type.ResolvedType
  - - com.fasterxml.jackson.databind.JavaType

- All Implemented Interfaces:
    java.io.Serializable, java.lang.reflect.Type
  Direct Known Subclasses:
    TypeBase

      public abstract class JavaType
      extends com.fasterxml.jackson.core.type.ResolvedType
      implements java.io.Serializable, java.lang.reflect.Type

  Base class for type token classes used both to contain information and as keys for deserializers.

  Instances can (only) be constructed by `com.fasterxml.jackson.databind.type.TypeFactory`.

  Since 2.2 this implements `Type` to allow it to be pushed through interfaces that only expose that type.

  See Also:
    Serialized Form

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected boolean` | `_asStatic` Whether entities defined with this type should be handled using static typing (as opposed to dynamic runtime type) or not.
    `protected java.lang.Class<?>` | `_class` This is the nominal type-erased Class that would be close to the type represented (but not exactly type, due to type erasure: type instance may have more information on this).
    `protected int` | `_hash`
    `protected java.lang.Object` | `_typeHandler` Optional handler that can be attached to indicate how to handle additional type metadata associated with this type.
    `protected java.lang.Object` | `_valueHandler` Optional handler (codec) that can be attached to indicate what to use for handling (serializing, deserializing) values of this specific type.

  - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `protected` | `JavaType(java.lang.Class<?> raw, int additionalHash, java.lang.Object valueHandler, java.lang.Object typeHandler, boolean asStatic)`
    `protected` | `JavaType(JavaType base)` Copy-constructor used when refining/upgrading type instances.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected abstract JavaType` | `_narrow(java.lang.Class<?> subclass)` Deprecated.
    `abstract JavaType` | `containedType(int index)`
    `abstract int` | `containedTypeCount()`
    `abstract java.lang.String` | `containedTypeName(int index)` Deprecated.
    `JavaType` | `containedTypeOrUnknown(int index)` Convenience method that is functionally same as: `JavaType t = containedType(index); if (t == null) { t = TypeFactory.unknownType(); }` and typically used to eliminate need for null checks for common case where we just want to check if containedType is available first; and if not, use "unknown type" (which translates to `java.lang.Object` basically).
    `abstract boolean` | `equals(java.lang.Object o)`
    `abstract JavaType` | `findSuperType(java.lang.Class<?> erasedTarget)` Method that may be called to find representation of given type within type hierarchy of this type: either this type (if this type has given erased type), one of its supertypes that has the erased types, or null if target is neither this type or any of its supertypes.
    `abstract JavaType[]` | `findTypeParameters(java.lang.Class<?> expType)` Method that may be used to find paramaterization this type has for given type-erased generic target type.
    `JavaType` | `forcedNarrowBy(java.lang.Class<?> subclass)` Deprecated.
    `abstract TypeBindings` | `getBindings()`
    `JavaType` | `getContentType()`
    `java.lang.Object` | `getContentTypeHandler()`
    `java.lang.Object` | `getContentValueHandler()`
    `java.lang.String` | `getErasedSignature()` Method for accessing signature without generic type information, in form compatible with all versions of JVM, and specifically used for type descriptions when generating byte code.
    `abstract java.lang.StringBuilder` | `getErasedSignature(java.lang.StringBuilder sb)` Method for accessing signature without generic type information, in form compatible with all versions of JVM, and specifically used for type descriptions when generating byte code.
    `java.lang.String` | `getGenericSignature()` Method for accessing signature that contains generic type information, in form compatible with JVM 1.5 as per JLS.
    `abstract java.lang.StringBuilder` | `getGenericSignature(java.lang.StringBuilder sb)`
    `abstract java.util.List<JavaType>` | `getInterfaces()` Accessor for finding fully resolved interfaces this type implements, if any; empty array if none.
    `JavaType` | `getKeyType()`
    `java.lang.Class<?>` | `getParameterSource()` Deprecated.
    `java.lang.Class<?>` | `getRawClass()`
    `JavaType` | `getReferencedType()`
    `abstract JavaType` | `getSuperClass()` Accessor for finding fully resolved parent class of this type, if it has one; null if not.
    `<T> T` | `getTypeHandler()` Method for accessing type handler associated with this type, if any
    `<T> T` | `getValueHandler()` Method for accessing value handler associated with this type, if any
    `boolean` | `hasContentType()` Accessor that allows determining whether `getContentType()` should return a non-null value (that is, there is a "content type") or not.
    `boolean` | `hasGenericTypes()`
    `boolean` | `hasHandlers()` Helper method that checks whether this type, or its (optional) key or content type has `getValueHandler()` or `getTypeHandler()`; that is, are there any non-standard handlers associated with this type object.
    `int` | `hashCode()`
    `boolean` | `hasRawClass(java.lang.Class<?> clz)` Method that can be used to check whether this type has specified Class as its type erasure.
    `boolean` | `hasValueHandler()`
    `boolean` | `isAbstract()`
    `boolean` | `isArrayType()`
    `boolean` | `isCollectionLikeType()`
    `boolean` | `isConcrete()` Convenience method for checking whether underlying Java type is a concrete class or not: abstract classes and interfaces are not.
    `abstract boolean` | `isContainerType()`
    `boolean` | `isEnumType()`
    `boolean` | `isFinal()`
    `boolean` | `isInterface()`
    `boolean` | `isJavaLangObject()` Convenience method, short-hand for `getRawClass() == Object.class` and used to figure if we basically have "untyped" type object.
    `boolean` | `isMapLikeType()`
    `boolean` | `isPrimitive()`
    `boolean` | `isThrowable()`
    `boolean` | `isTypeOrSubTypeOf(java.lang.Class<?> clz)`
    `abstract JavaType` | `refine(java.lang.Class<?> rawType, TypeBindings bindings, JavaType superClass, JavaType[] superInterfaces)` Mutant factory method that will try to create and return a sub-type instance for known parameterized types; for other types will return `null` to indicate that no just refinement makes necessary sense, without trying to detect special status through implemented interfaces.
    `abstract java.lang.String` | `toString()`
    `boolean` | `useStaticType()` Accessor for checking whether handlers for dealing with values of this type should use static typing (as opposed to dynamic typing).
    `abstract JavaType` | `withContentType(JavaType contentType)` Mutant factory method that may be called on structured types that have a so-called content type (element of arrays, value type of Maps, referenced type of referential types), and will construct a new instance that is identical to this instance, except that it has specified content type, instead of current one.
    `abstract JavaType` | `withContentTypeHandler(java.lang.Object h)` Mutant factory method that will construct a new instance that is identical to this instance, except that it will have specified content type (element type for arrays, value type for Maps and so forth) handler assigned.
    `abstract JavaType` | `withContentValueHandler(java.lang.Object h)` Mutant factory method that will construct a new instance that is identical to this instance, except that it will have specified content value handler assigned.
    `JavaType` | `withHandlersFrom(JavaType src)` Mutant factory method that will try to copy handlers that the specified source type instance had, if any; this must be done recursively where necessary (as content types may be structured).
    `abstract JavaType` | `withStaticTyping()` Method that can be called to get a type instance that indicates that values of the type should be handled using "static typing" for purposes of serialization (as opposed to "dynamic" aka runtime typing): meaning that no runtime information is needed for determining serializers to use.
    `abstract JavaType` | `withTypeHandler(java.lang.Object h)` "Copy method" that will construct a new instance that is identical to this instance, except that it will have specified type handler assigned.
    `abstract JavaType` | `withValueHandler(java.lang.Object h)` Mutant factory method that will construct a new instance that is identical to this instance, except that it will have specified value handler assigned.

    - ### Methods inherited from class com.fasterxml.jackson.core.type.ResolvedType

      `isReferenceType, toCanonical`

    - ### Methods inherited from class java.lang.Object

      `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

- - ### Field Detail

    - #### _class

          protected final java.lang.Class<?> _class

      This is the nominal type-erased Class that would be close to the type represented (but not exactly type, due to type erasure: type instance may have more information on this). May be an interface or abstract class, so instantiation may not be possible.

    - #### _hash

          protected final int _hash

    - #### _valueHandler

          protected final java.lang.Object _valueHandler

      Optional handler (codec) that can be attached to indicate what to use for handling (serializing, deserializing) values of this specific type.

      Note: untyped (i.e. caller has to cast) because it is used for different kinds of handlers, with unrelated types.

    - #### _typeHandler

          protected final java.lang.Object _typeHandler

      Optional handler that can be attached to indicate how to handle additional type metadata associated with this type.

      Note: untyped (i.e. caller has to cast) because it is used for different kinds of handlers, with unrelated types.

    - #### _asStatic

          protected final boolean _asStatic

      Whether entities defined with this type should be handled using static typing (as opposed to dynamic runtime type) or not.
      Since:
        2.2

  - ### Constructor Detail

    - #### JavaType

          protected JavaType(java.lang.Class<?> raw,
                  int additionalHash,
                  java.lang.Object valueHandler,
                  java.lang.Object typeHandler,
                  boolean asStatic)

      Parameters:
        `raw` - "Raw" (type-erased) class for this type
        `additionalHash` - Additional hash code to use, in addition to hash code of the class name

    - #### JavaType

          protected JavaType(JavaType base)

      Copy-constructor used when refining/upgrading type instances.
      Since:
        2.7

  - ### Method Detail

    - #### withTypeHandler

          public abstract JavaType withTypeHandler(java.lang.Object h)

      "Copy method" that will construct a new instance that is identical to this instance, except that it will have specified type handler assigned.
      Returns:
        Newly created type instance

    - #### withContentTypeHandler

          public abstract JavaType withContentTypeHandler(java.lang.Object h)

      Mutant factory method that will construct a new instance that is identical to this instance, except that it will have specified content type (element type for arrays, value type for Maps and so forth) handler assigned.
      Returns:
        Newly created type instance, with given

    - #### withValueHandler

          public abstract JavaType withValueHandler(java.lang.Object h)

      Mutant factory method that will construct a new instance that is identical to this instance, except that it will have specified value handler assigned.
      Returns:
        Newly created type instance

    - #### withContentValueHandler

          public abstract JavaType withContentValueHandler(java.lang.Object h)

      Mutant factory method that will construct a new instance that is identical to this instance, except that it will have specified content value handler assigned.
      Returns:
        Newly created type instance

    - #### withHandlersFrom

          public JavaType withHandlersFrom(JavaType src)

      Mutant factory method that will try to copy handlers that the specified source type instance had, if any; this must be done recursively where necessary (as content types may be structured).
      Since:
        2.8.4

    - #### withContentType

          public abstract JavaType withContentType(JavaType contentType)

      Mutant factory method that may be called on structured types that have a so-called content type (element of arrays, value type of Maps, referenced type of referential types), and will construct a new instance that is identical to this instance, except that it has specified content type, instead of current one. If content type is already set to given type, `this` is returned. If type does not have a content type (which is the case with `SimpleType`), `IllegalArgumentException` will be thrown.
      Returns:
        Newly created type instance
      Since:
        2.7

    - #### withStaticTyping

          public abstract JavaType withStaticTyping()

      Method that can be called to get a type instance that indicates that values of the type should be handled using "static typing" for purposes of serialization (as opposed to "dynamic" aka runtime typing): meaning that no runtime information is needed for determining serializers to use. The main use case is to allow forcing of specific root value serialization type, and specifically in resolving serializers for contained types (element types for arrays, Collections and Maps).
      Since:
        2.2

    - #### refine

          public abstract JavaType refine(java.lang.Class<?> rawType,
                        TypeBindings bindings,
                        JavaType superClass,
                        JavaType[] superInterfaces)

      Mutant factory method that will try to create and return a sub-type instance for known parameterized types; for other types will return `null` to indicate that no just refinement makes necessary sense, without trying to detect special status through implemented interfaces.
      Since:
        2.7

    - #### forcedNarrowBy

          @Deprecated
          public JavaType forcedNarrowBy(java.lang.Class<?> subclass)

      Deprecated.
      Legacy method used for forcing sub-typing of this type into type specified by specific type erasure. Deprecated as of 2.7 as such specializations really ought to go through `TypeFactory`, not directly via `JavaType`.
      Since:
        2.7

    - #### _narrow

          @Deprecated
          protected abstract JavaType _narrow(java.lang.Class<?> subclass)

      Deprecated.

    - #### getRawClass

          public final java.lang.Class<?> getRawClass()

      Specified by:
        `getRawClass` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### hasRawClass

          public final boolean hasRawClass(java.lang.Class<?> clz)

      Method that can be used to check whether this type has specified Class as its type erasure. Put another way, returns true if instantiation of this Type is given (type-erased) Class.
      Specified by:
        `hasRawClass` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### hasContentType

          public boolean hasContentType()

      Accessor that allows determining whether `getContentType()` should return a non-null value (that is, there is a "content type") or not. True if `isContainerType()` or `ResolvedType.isReferenceType()` return true.
      Since:
        2.8

    - #### isTypeOrSubTypeOf

          public final boolean isTypeOrSubTypeOf(java.lang.Class<?> clz)

      Since:
        2.6

    - #### isAbstract

          public boolean isAbstract()

      Specified by:
        `isAbstract` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### isConcrete

          public boolean isConcrete()

      Convenience method for checking whether underlying Java type is a concrete class or not: abstract classes and interfaces are not.
      Specified by:
        `isConcrete` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### isThrowable

          public boolean isThrowable()

      Specified by:
        `isThrowable` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### isArrayType

          public boolean isArrayType()

      Specified by:
        `isArrayType` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### isEnumType

          public final boolean isEnumType()

      Specified by:
        `isEnumType` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### isInterface

          public final boolean isInterface()

      Specified by:
        `isInterface` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### isPrimitive

          public final boolean isPrimitive()

      Specified by:
        `isPrimitive` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### isFinal

          public final boolean isFinal()

      Specified by:
        `isFinal` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### isContainerType

          public abstract boolean isContainerType()

      Specified by:
        `isContainerType` in class `com.fasterxml.jackson.core.type.ResolvedType`
      Returns:
        True if type represented is a container type; this includes array, Map and Collection types.

    - #### isCollectionLikeType

          public boolean isCollectionLikeType()

      Specified by:
        `isCollectionLikeType` in class `com.fasterxml.jackson.core.type.ResolvedType`
      Returns:
        True if type is either true `Collection` type, or something similar (meaning it has at least one type parameter, which describes type of contents)

    - #### isMapLikeType

          public boolean isMapLikeType()

      Specified by:
        `isMapLikeType` in class `com.fasterxml.jackson.core.type.ResolvedType`
      Returns:
        True if type is either true `Map` type, or something similar (meaning it has at least two type parameter; first one describing key type, second value type)

    - #### isJavaLangObject

          public final boolean isJavaLangObject()

      Convenience method, short-hand for `getRawClass() == Object.class` and used to figure if we basically have "untyped" type object.
      Since:
        2.5

    - #### useStaticType

          public final boolean useStaticType()

      Accessor for checking whether handlers for dealing with values of this type should use static typing (as opposed to dynamic typing). Note that while value of 'true' does mean that static typing is to be used, value of 'false' may still be overridden by other settings.
      Since:
        2.2

    - #### hasGenericTypes

          public boolean hasGenericTypes()

      Specified by:
        `hasGenericTypes` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### getKeyType

          public JavaType getKeyType()

      Specified by:
        `getKeyType` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### getContentType

          public JavaType getContentType()

      Specified by:
        `getContentType` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### getReferencedType

          public JavaType getReferencedType()

      Specified by:
        `getReferencedType` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### containedTypeCount

          public abstract int containedTypeCount()

      Specified by:
        `containedTypeCount` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### containedType

          public abstract JavaType containedType(int index)

      Specified by:
        `containedType` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### containedTypeName

          @Deprecated
          public abstract java.lang.String containedTypeName(int index)

      Deprecated.
      Specified by:
        `containedTypeName` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### getParameterSource

          @Deprecated
          public java.lang.Class<?> getParameterSource()

      Deprecated.
      Overrides:
        `getParameterSource` in class `com.fasterxml.jackson.core.type.ResolvedType`

    - #### containedTypeOrUnknown

          public JavaType containedTypeOrUnknown(int index)

      Convenience method that is functionally same as: `JavaType t = containedType(index); if (t == null) { t = TypeFactory.unknownType(); }` and typically used to eliminate need for null checks for common case where we just want to check if containedType is available first; and if not, use "unknown type" (which translates to `java.lang.Object` basically).
      Since:
        2.5

    - #### getBindings

          public abstract TypeBindings getBindings()

      Since:
        2.7

    - #### findSuperType

          public abstract JavaType findSuperType(java.lang.Class<?> erasedTarget)

      Method that may be called to find representation of given type within type hierarchy of this type: either this type (if this type has given erased type), one of its supertypes that has the erased types, or null if target is neither this type or any of its supertypes.
      Since:
        2.7

    - #### getSuperClass

          public abstract JavaType getSuperClass()

      Accessor for finding fully resolved parent class of this type, if it has one; null if not.
      Since:
        2.7

    - #### getInterfaces

          public abstract java.util.List<JavaType> getInterfaces()

      Accessor for finding fully resolved interfaces this type implements, if any; empty array if none.
      Since:
        2.7

    - #### findTypeParameters

          public abstract JavaType[] findTypeParameters(java.lang.Class<?> expType)

      Method that may be used to find paramaterization this type has for given type-erased generic target type.
      Since:
        2.7

    - #### getValueHandler

          public <T> T getValueHandler()

      Method for accessing value handler associated with this type, if any

    - #### getTypeHandler

          public <T> T getTypeHandler()

      Method for accessing type handler associated with this type, if any

    - #### getContentValueHandler

          public java.lang.Object getContentValueHandler()

      Since:
        2.7

    - #### getContentTypeHandler

          public java.lang.Object getContentTypeHandler()

      Since:
        2.7

    - #### hasValueHandler

          public boolean hasValueHandler()

      Since:
        2.6

    - #### hasHandlers

          public boolean hasHandlers()

      Helper method that checks whether this type, or its (optional) key or content type has `getValueHandler()` or `getTypeHandler()`; that is, are there any non-standard handlers associated with this type object.
      Since:
        2.8

    - #### getGenericSignature

          public java.lang.String getGenericSignature()

      Method for accessing signature that contains generic type information, in form compatible with JVM 1.5 as per JLS. It is a superset of `getErasedSignature()`, in that generic information can be automatically removed if necessary (just remove outermost angle brackets along with content inside)

    - #### getGenericSignature

          public abstract java.lang.StringBuilder getGenericSignature(java.lang.StringBuilder sb)

      Parameters:
        `sb` - StringBuilder to append signature to
      Returns:
        StringBuilder that was passed in; returned to allow call chaining

    - #### getErasedSignature

          public java.lang.String getErasedSignature()

      Method for accessing signature without generic type information, in form compatible with all versions of JVM, and specifically used for type descriptions when generating byte code.

    - #### getErasedSignature

          public abstract java.lang.StringBuilder getErasedSignature(java.lang.StringBuilder sb)

      Method for accessing signature without generic type information, in form compatible with all versions of JVM, and specifically used for type descriptions when generating byte code.
      Parameters:
        `sb` - StringBuilder to append signature to
      Returns:
        StringBuilder that was passed in; returned to allow call chaining

    - #### toString

          public abstract java.lang.String toString()

      Overrides:
        `toString` in class `java.lang.Object`

    - #### equals

          public abstract boolean equals(java.lang.Object o)

      Overrides:
        `equals` in class `java.lang.Object`

    - #### hashCode

          public final int hashCode()

      Overrides:
        `hashCode` in class `java.lang.Object`