com.fasterxml.jackson.databind.deser

## Class ValueInstantiator

- java.lang.Object
- - com.fasterxml.jackson.databind.deser.ValueInstantiator

- Direct Known Subclasses:
    StdValueInstantiator, ValueInstantiator.Base

      public abstract class ValueInstantiator
      extends Object

  Class that defines simple API implemented by objects that create value instances. Some or all of properties of value instances may be initialized by instantiator, rest being populated by deserializer, to which value instance is passed. Since different kinds of JSON values (structured and scalar) may be bound to Java values, in some cases instantiator fully defines resulting value; this is the case when JSON value is a scalar value (String, number, boolean).

  Note that this type is not parameterized (even though it would seemingly make sense), because such type information can not be use effectively during runtime: access is always using either wildcard type, or just basic `Object`; and so adding type parameter seems like unnecessary extra work.

  Actual implementations are strongly recommended to be based on `StdValueInstantiator` which implements all methods, and as such will be compatible across versions even if new methods were added to this interface.

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class and Description
    --- | ---
    `static class` | `ValueInstantiator.Base` Partial `ValueInstantiator` implementation that is strongly recommended to be used instead of directly extending `ValueInstantiator` itself.

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `ValueInstantiator()`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected Object` | `_createFromStringFallbacks(DeserializationContext ctxt, String value)`
    `boolean` | `canCreateFromBoolean()` Method that can be called to check whether a double (boolean / Boolean) based creator is available to use (to call `createFromDouble(com.fasterxml.jackson.databind.DeserializationContext, double)`).
    `boolean` | `canCreateFromDouble()` Method that can be called to check whether a double (double / Double) based creator is available to use (to call `createFromDouble(com.fasterxml.jackson.databind.DeserializationContext, double)`).
    `boolean` | `canCreateFromInt()` Method that can be called to check whether an integer (int, Integer) based creator is available to use (to call `createFromInt(com.fasterxml.jackson.databind.DeserializationContext, int)`).
    `boolean` | `canCreateFromLong()` Method that can be called to check whether a long (long, Long) based creator is available to use (to call `createFromLong(com.fasterxml.jackson.databind.DeserializationContext, long)`).
    `boolean` | `canCreateFromObjectWith()` Method that can be called to check whether a property-based creator (argument-taking constructor or factory method) is available to instantiate values from JSON Object
    `boolean` | `canCreateFromString()` Method that can be called to check whether a String-based creator is available for this instantiator
    `boolean` | `canCreateUsingArrayDelegate()` Method that can be called to check whether a array-delegate-based creator (single-arg constructor or factory method) is available for this instantiator
    `boolean` | `canCreateUsingDefault()` Method that can be called to check whether a default creator (constructor, or no-arg static factory method) is available for this instantiator
    `boolean` | `canCreateUsingDelegate()` Method that can be called to check whether a delegate-based creator (single-arg constructor or factory method) is available for this instantiator
    `boolean` | `canInstantiate()` Method that will return true if any of `canCreateXxx` method returns true: that is, if there is any way that an instance could be created.
    `Object` | `createFromBoolean(DeserializationContext ctxt, boolean value)`
    `Object` | `createFromDouble(DeserializationContext ctxt, double value)`
    `Object` | `createFromInt(DeserializationContext ctxt, int value)`
    `Object` | `createFromLong(DeserializationContext ctxt, long value)`
    `Object` | `createFromObjectWith(DeserializationContext ctxt, Object[] args)` Method called to create value instance from JSON Object when instantiation arguments are passed; this is done, for example when passing information specified with "Creator" annotations.
    `Object` | `createFromObjectWith(DeserializationContext ctxt, SettableBeanProperty[] props, PropertyValueBuffer buffer)` Method that delegates to `createFromObjectWith(DeserializationContext, Object[])` by default, but can be overridden if the application should have customized behavior with respect to missing properties.
    `Object` | `createFromString(DeserializationContext ctxt, String value)`
    `Object` | `createUsingArrayDelegate(DeserializationContext ctxt, Object delegate)` Method to called to create value instance from JSON Array using an intermediate "delegate" value to pass to createor method
    `Object` | `createUsingDefault(DeserializationContext ctxt)` Method called to create value instance from a JSON value when no data needs to passed to creator (constructor, factory method); typically this will call the default constructor of the value object.
    `Object` | `createUsingDelegate(DeserializationContext ctxt, Object delegate)` Method to called to create value instance from JSON Object using an intermediate "delegate" value to pass to createor method
    `AnnotatedWithParams` | `getArrayDelegateCreator()` Method that can be called to try to access member (constructor, static factory method) that is used as the "array delegate creator".
    `JavaType` | `getArrayDelegateType(DeserializationConfig config)` Method that can be used to determine what is the type of array delegate type to use, if any; if no delegates are used, will return null.
    `AnnotatedWithParams` | `getDefaultCreator()` Method that can be called to try to access member (constructor, static factory method) that is used as the "default creator" (creator that is called without arguments; typically default [zero-argument] constructor of the type).
    `AnnotatedWithParams` | `getDelegateCreator()` Method that can be called to try to access member (constructor, static factory method) that is used as the "delegate creator".
    `JavaType` | `getDelegateType(DeserializationConfig config)` Method that can be used to determine what is the type of delegate type to use, if any; if no delegates are used, will return null.
    `SettableBeanProperty[]` | `getFromObjectArguments(DeserializationConfig config)` Method called to determine types of instantiation arguments to use when creating instances with creator arguments (when `canCreateFromObjectWith()` returns true).
    `AnnotatedParameter` | `getIncompleteParameter()` If an incomplete creator was found, this is the first parameter that needs further annotation to help make the creator complete.
    `Class<?>` | `getValueClass()` Accessor for raw (type-erased) type of instances to create.
    `String` | `getValueTypeDesc()` Method that returns description of the value type this instantiator handles.
    `AnnotatedWithParams` | `getWithArgsCreator()` Method that can be called to try to access member (constructor, static factory method) that is used as the "non-default creator" (constructor or factory method that takes one or more arguments).

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

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### ValueInstantiator

          public ValueInstantiator()

  - ### Method Detail

    - #### getValueClass

          public Class<?> getValueClass()

      Accessor for raw (type-erased) type of instances to create.

      NOTE: since this method has not existed since beginning of Jackson 2.0 series, default implementation will just return `Object.class`; implementations are expected to override it with real value.

      Since:
        2.8

    - #### getValueTypeDesc

          public String getValueTypeDesc()

      Method that returns description of the value type this instantiator handles. Used for error messages, diagnostics.

    - #### canInstantiate

          public boolean canInstantiate()

      Method that will return true if any of `canCreateXxx` method returns true: that is, if there is any way that an instance could be created.

    - #### canCreateFromString

          public boolean canCreateFromString()

      Method that can be called to check whether a String-based creator is available for this instantiator

    - #### canCreateFromInt

          public boolean canCreateFromInt()

      Method that can be called to check whether an integer (int, Integer) based creator is available to use (to call `createFromInt(com.fasterxml.jackson.databind.DeserializationContext, int)`).

    - #### canCreateFromLong

          public boolean canCreateFromLong()

      Method that can be called to check whether a long (long, Long) based creator is available to use (to call `createFromLong(com.fasterxml.jackson.databind.DeserializationContext, long)`).

    - #### canCreateFromDouble

          public boolean canCreateFromDouble()

      Method that can be called to check whether a double (double / Double) based creator is available to use (to call `createFromDouble(com.fasterxml.jackson.databind.DeserializationContext, double)`).

    - #### canCreateFromBoolean

          public boolean canCreateFromBoolean()

      Method that can be called to check whether a double (boolean / Boolean) based creator is available to use (to call `createFromDouble(com.fasterxml.jackson.databind.DeserializationContext, double)`).

    - #### canCreateUsingDefault

          public boolean canCreateUsingDefault()

      Method that can be called to check whether a default creator (constructor, or no-arg static factory method) is available for this instantiator

    - #### canCreateUsingDelegate

          public boolean canCreateUsingDelegate()

      Method that can be called to check whether a delegate-based creator (single-arg constructor or factory method) is available for this instantiator

    - #### canCreateUsingArrayDelegate

          public boolean canCreateUsingArrayDelegate()

      Method that can be called to check whether a array-delegate-based creator (single-arg constructor or factory method) is available for this instantiator

    - #### canCreateFromObjectWith

          public boolean canCreateFromObjectWith()

      Method that can be called to check whether a property-based creator (argument-taking constructor or factory method) is available to instantiate values from JSON Object

    - #### getFromObjectArguments

          public SettableBeanProperty[] getFromObjectArguments(DeserializationConfig config)

      Method called to determine types of instantiation arguments to use when creating instances with creator arguments (when `canCreateFromObjectWith()` returns true). These arguments are bound from JSON, using specified property types to locate deserializers.

      NOTE: all properties will be of type `CreatorProperty`.

    - #### getDelegateType

          public JavaType getDelegateType(DeserializationConfig config)

      Method that can be used to determine what is the type of delegate type to use, if any; if no delegates are used, will return null. If non-null type is returned, deserializer will bind JSON into specified type (using standard deserializer for that type), and pass that to instantiator.

    - #### getArrayDelegateType

          public JavaType getArrayDelegateType(DeserializationConfig config)

      Method that can be used to determine what is the type of array delegate type to use, if any; if no delegates are used, will return null. If non-null type is returned, deserializer will bind JSON into specified type (using standard deserializer for that type), and pass that to instantiator.

    - #### createUsingDefault

          public Object createUsingDefault(DeserializationContext ctxt)
                                    throws IOException

      Method called to create value instance from a JSON value when no data needs to passed to creator (constructor, factory method); typically this will call the default constructor of the value object. It will only be used if more specific creator methods are not applicable; hence "default".

      This method is called if `getFromObjectArguments(com.fasterxml.jackson.databind.DeserializationConfig)` returns null or empty List.

      Throws:
        `IOException`

    - #### createFromObjectWith

          public Object createFromObjectWith(DeserializationContext ctxt,
                                    Object[] args)
                                      throws IOException

      Method called to create value instance from JSON Object when instantiation arguments are passed; this is done, for example when passing information specified with "Creator" annotations.

      This method is called if `getFromObjectArguments(com.fasterxml.jackson.databind.DeserializationConfig)` returns a non-empty List of arguments.

      Throws:
        `IOException`

    - #### createFromObjectWith

          public Object createFromObjectWith(DeserializationContext ctxt,
                                    SettableBeanProperty[] props,
                                    PropertyValueBuffer buffer)
                                      throws IOException

      Method that delegates to `createFromObjectWith(DeserializationContext, Object[])` by default, but can be overridden if the application should have customized behavior with respect to missing properties.

      The default implementation of this method uses `PropertyValueBuffer.getParameters(SettableBeanProperty[])` to read and validate all properties in bulk, possibly substituting defaults for missing properties or throwing exceptions for missing properties. An overridden implementation of this method could, for example, use `PropertyValueBuffer.hasParameter(SettableBeanProperty)` and `PropertyValueBuffer.getParameter(SettableBeanProperty)` to safely read the present properties only, and to have some other behavior for the missing properties.

      Throws:
        `IOException`
      Since:
        2.8

    - #### createUsingDelegate

          public Object createUsingDelegate(DeserializationContext ctxt,
                                   Object delegate)
                                     throws IOException

      Method to called to create value instance from JSON Object using an intermediate "delegate" value to pass to createor method
      Throws:
        `IOException`

    - #### createUsingArrayDelegate

          public Object createUsingArrayDelegate(DeserializationContext ctxt,
                                        Object delegate)
                                          throws IOException

      Method to called to create value instance from JSON Array using an intermediate "delegate" value to pass to createor method
      Throws:
        `IOException`

    - #### createFromString

          public Object createFromString(DeserializationContext ctxt,
                                String value)
                                  throws IOException

      Throws:
        `IOException`

    - #### createFromInt

          public Object createFromInt(DeserializationContext ctxt,
                             int value)
                               throws IOException

      Throws:
        `IOException`

    - #### createFromLong

          public Object createFromLong(DeserializationContext ctxt,
                              long value)
                                throws IOException

      Throws:
        `IOException`

    - #### createFromDouble

          public Object createFromDouble(DeserializationContext ctxt,
                                double value)
                                  throws IOException

      Throws:
        `IOException`

    - #### createFromBoolean

          public Object createFromBoolean(DeserializationContext ctxt,
                                 boolean value)
                                   throws IOException

      Throws:
        `IOException`

    - #### getDefaultCreator

          public AnnotatedWithParams getDefaultCreator()

      Method that can be called to try to access member (constructor, static factory method) that is used as the "default creator" (creator that is called without arguments; typically default [zero-argument] constructor of the type). Note that implementations not required to return actual object they use (or, they may use some other instantiation) method. That is, even if `canCreateUsingDefault()` returns true, this method may return null .

    - #### getDelegateCreator

          public AnnotatedWithParams getDelegateCreator()

      Method that can be called to try to access member (constructor, static factory method) that is used as the "delegate creator". Note that implementations not required to return actual object they use (or, they may use some other instantiation) method. That is, even if `canCreateUsingDelegate()` returns true, this method may return null .

    - #### getArrayDelegateCreator

          public AnnotatedWithParams getArrayDelegateCreator()

      Method that can be called to try to access member (constructor, static factory method) that is used as the "array delegate creator". Note that implementations not required to return actual object they use (or, they may use some other instantiation) method. That is, even if `canCreateUsingArrayDelegate()` returns true, this method may return null .

    - #### getWithArgsCreator

          public AnnotatedWithParams getWithArgsCreator()

      Method that can be called to try to access member (constructor, static factory method) that is used as the "non-default creator" (constructor or factory method that takes one or more arguments). Note that implementations not required to return actual object they use (or, they may use some other instantiation) method. That is, even if `canCreateFromObjectWith()` returns true, this method may return null .

    - #### getIncompleteParameter

          public AnnotatedParameter getIncompleteParameter()

      If an incomplete creator was found, this is the first parameter that needs further annotation to help make the creator complete.

    - #### _createFromStringFallbacks

          protected Object _createFromStringFallbacks(DeserializationContext ctxt,
                                          String value)
                                               throws IOException

      Throws:
        `IOException`
      Since:
        2.4 (demoted from `StdValueInstantiator`)

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