com.alibaba.fastjson2.JSONReader.Feature

All Implemented Interfaces:: Serializable, Comparable<JSONReader.Feature>, java.lang.constant.Constable

Enclosing class:: JSONReader

public static enum JSONReader.Feature extends Enum<JSONReader.Feature>

Feature is used to control the behavior of JSON reading and parsing in FASTJSON2. Each feature represents a specific configuration option that can be enabled or disabled to customize how JSON data is processed during deserialization.

Features can be enabled in several ways:

Using factory methods like JSONReader.of(String, Context) with JSONFactory.createReadContext(JSONReader.Feature...)
Using JSONReader.Context.config(Feature...) method
Using JSONFactory.getDefaultReaderFeatures() for global configuration

Example usage:

 // Enable FieldBased feature for this reader only
 try (JSONReader reader = JSONReader.of(json, JSONReader.Feature.FieldBased)) {
     MyObject obj = reader.read(MyObject.class);
 }

 // Enable multiple features
 try (JSONReader reader = JSONReader.of(json,
         JSONReader.Feature.FieldBased,
         JSONReader.Feature.TrimString)) {
     MyObject obj = reader.read(MyObject.class);
 }

 // Using context configuration
 JSONReader.Context context = new JSONReader.Context();
 context.config(JSONReader.Feature.FieldBased);
 try (JSONReader reader = JSONReader.of(json, context)) {
     MyObject obj = reader.read(MyObject.class);
 }

Features are implemented as bitmask flags for efficient storage and checking. Each feature has a unique mask value that is used internally to determine whether the feature is enabled in a given configuration.

Since:

2.0.0

See Also:

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Enum
Enum.EnumDesc<E extends Enum<E>>
Enum Constant Summary

Enum Constants

Enum Constant

Description

AllowUnQuotedFieldNames

Feature that determines whether to allow unquoted field names in JSON.

Base64StringAsByteArray

Feature that determines whether to treat Base64-encoded strings as byte arrays during deserialization.

DisableReferenceDetect

Feature that disables reference detection during deserialization.

DisableSingleQuote

Feature that disables the support for single quote.

DisableStringArrayUnwrapping

Feature that determines whether to unwrap single-element string arrays to scalar values.

DuplicateKeyValueAsArray

Feature that determines how to handle duplicate keys in JSON objects.

EmptyStringAsNull

Feature that determines whether to convert empty strings to null values during deserialization.

ErrorOnEnumNotMatch

Feature that determines whether to throw an exception when an enum value in JSON does not match any of the defined enum constants.

ErrorOnNoneSerializable

Feature that determines whether to throw an exception when encountering non-serializable classes during deserialization.

ErrorOnNotSupportAutoType

Feature that determines whether to throw an exception when autoType is not supported.

ErrorOnNullForPrimitives

Feature that determines whether to throw an exception when null values are encountered for primitive types during deserialization.

ErrorOnUnknownProperties

Feature that determines whether to throw an exception when unknown properties are encountered during deserialization.

FieldBased

Feature that determines whether to use field-based deserialization instead of getter/setter-based deserialization.

IgnoreAutoTypeNotMatch

Feature that determines whether to ignore autoType mismatches during deserialization.

IgnoreCheckClose

Feature that determines whether to ignore checking for resource cleanup.

IgnoreNoneSerializable

Feature that determines whether to ignore non-serializable classes during deserialization.

IgnoreNullPropertyValue

Feature that determines whether to ignore null property values during deserialization.

IgnoreSetNullValue

Feature that determines whether to ignore null values when setting properties.

InitStringFieldAsEmpty

Feature that determines whether to initialize string fields as empty strings instead of null values.

NonErrorOnNumberOverflow

Feature that determines whether to avoid throwing exceptions on number overflow during deserialization.

NonStringKeyAsString

Feature that determines whether to treat non-string keys as strings during deserialization.

NonZeroNumberCastToBooleanAsTrue

Feature that determines whether to cast non-zero numbers to boolean true during deserialization.

NullOnError

Feature that determines whether to return null on error during deserialization.

SupportArrayToBean

Feature that determines whether to support deserializing JSON arrays into Java beans.

SupportAutoType

Deprecated.
It is not safe to explicitly turn on autoType, it is recommended to use AutoTypeBeforeHandler

SupportClassForName

Feature that enables support for Class.forName() during deserialization.

SupportSmartMatch

Feature that enables smart matching of field names during deserialization.

TrimString

Feature that determines whether to trim whitespace from string values during deserialization.

UseBigDecimalForDoubles

Feature that determines whether to deserialize floating-point numbers as BigDecimal when the target type is double.

UseBigDecimalForFloats

Feature that determines whether to deserialize floating-point numbers as BigDecimal when the target type is float.

UseBigIntegerForInts

Feature that determines whether JSON integral (non-floating-point) numbers are to be deserialized into BigIntegers if only generic type description (either Object or Number, or within untyped Map or Collection context) is available.

UseDefaultConstructorAsPossible

Feature that determines whether to use default constructors as much as possible during deserialization.

UseDoubleForDecimals

Feature that determines whether to deserialize decimal numbers as double values.

UseLongForInts

Feature that determines how "small" JSON integral (non-floating-point) numbers -- ones that fit in 32-bit signed integer (`int`) -- are bound when target type is loosely typed as Object or Number (or within untyped Map or Collection context).

UseNativeObject

Feature that determines whether to use native Java objects (HashMap, ArrayList) instead of FASTJSON's JSONObject and JSONArray during deserialization.
Field Summary

Fields

Modifier and Type

Field

Description

final long

mask
Method Summary

Modifier and Type

Method

Description

boolean

isEnabled(long features)

Checks if this feature is enabled in the specified features bitmask.

static boolean

isEnabled(long features, JSONReader.Feature feature)

Checks if the specified feature is enabled in the given features bitmask.

static long

of(JSONReader.Feature[] features)

Combines the masks of the specified features into a single bitmask.

static JSONReader.Feature

valueOf(String name)

Returns the enum constant of this type with the specified name.

static JSONReader.Feature[]

values()

Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum
clone, compareTo, describeConstable, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait

Enum Constant Details
- FieldBased
  
  public static final JSONReader.Feature FieldBased
  
  Feature that determines whether to use field-based deserialization instead of getter/setter-based deserialization. When enabled, fields are directly accessed rather than using getter and setter methods. This can improve performance but may bypass validation logic in setters.
  By default, this feature is disabled, meaning that getter/setter-based deserialization is used.
  
  Since:
  
  2.0.0
- IgnoreNoneSerializable
  
  public static final JSONReader.Feature IgnoreNoneSerializable
  
  Feature that determines whether to ignore non-serializable classes during deserialization. When enabled, classes that do not implement Serializable will be ignored rather than causing an exception to be thrown.
  By default, this feature is disabled, meaning that non-serializable classes are not ignored.
  
  Since:
  
  2.0.0
- ErrorOnNoneSerializable
  
  public static final JSONReader.Feature ErrorOnNoneSerializable
  
  Feature that determines whether to throw an exception when encountering non-serializable classes during deserialization. When enabled, an exception will be thrown if a class does not implement Serializable.
  By default, this feature is disabled, meaning that no exception is thrown for non-serializable classes.
  
  Since:
  
  2.0.14
- SupportArrayToBean
  
  public static final JSONReader.Feature SupportArrayToBean
  
  Feature that determines whether to support deserializing JSON arrays into Java beans. When enabled, JSON arrays can be mapped to Java bean properties, with each array element corresponding to a property in the bean.
  By default, this feature is disabled, meaning that array-to-bean conversion is not supported.
  
  Since:
  
  2.0.0
- InitStringFieldAsEmpty
  
  public static final JSONReader.Feature InitStringFieldAsEmpty
  
  Feature that determines whether to initialize string fields as empty strings instead of null values. When enabled, string fields will be initialized with empty strings ("") rather than null.
  By default, this feature is disabled, meaning that string fields are initialized with null values.
  
  Since:
  
  2.0.0
- SupportAutoType
  
  @Deprecated public static final JSONReader.Feature SupportAutoType
  
  Deprecated.
  It is not safe to explicitly turn on autoType, it is recommended to use AutoTypeBeforeHandler
  
  Feature that enables automatic type detection during deserialization. It is not safe to explicitly turn on autoType, it is recommended to use AutoTypeBeforeHandler.
  This feature is deprecated and should not be used in production code.
  
  Since:
  
  2.0.0
- SupportSmartMatch
  
  public static final JSONReader.Feature SupportSmartMatch
  
  Feature that enables smart matching of field names during deserialization. When enabled, field names in JSON can be matched to Java bean properties in a case-insensitive manner or with other smart matching rules.
  By default, this feature is disabled, meaning that exact field name matching is required.
  
  Since:
  
  2.0.0
- UseNativeObject
  
  public static final JSONReader.Feature UseNativeObject
  
  Feature that determines whether to use native Java objects (HashMap, ArrayList) instead of FASTJSON's JSONObject and JSONArray during deserialization. When enabled, standard Java collections are used rather than FASTJSON-specific ones.
  By default, this feature is disabled, meaning that FASTJSON's JSONObject and JSONArray are used.
  
  Since:
  
  2.0.0
- SupportClassForName
  
  public static final JSONReader.Feature SupportClassForName
  
  Feature that enables support for Class.forName() during deserialization. When enabled, the deserializer can use Class.forName() to load classes by name.
  By default, this feature is disabled.
  
  Since:
  
  2.0.0
- IgnoreSetNullValue
  
  public static final JSONReader.Feature IgnoreSetNullValue
  
  Feature that determines whether to ignore null values when setting properties. When enabled, null values in JSON will not be set on Java bean properties, preserving their default values.
  By default, this feature is disabled, meaning that null values are set on properties.
  
  Since:
  
  2.0.0
- UseDefaultConstructorAsPossible
  
  public static final JSONReader.Feature UseDefaultConstructorAsPossible
  
  Feature that determines whether to use default constructors as much as possible during deserialization. When enabled, the deserializer will prefer to use default (no-argument) constructors when creating objects.
  By default, this feature is disabled.
  
  Since:
  
  2.0.0
- UseBigDecimalForFloats
  
  public static final JSONReader.Feature UseBigDecimalForFloats
  
  Feature that determines whether to deserialize floating-point numbers as BigDecimal when the target type is float. When enabled, float values will be represented with higher precision using BigDecimal.
  By default, this feature is disabled, meaning that standard float precision is used.
  
  Since:
  
  2.0.0
- UseBigDecimalForDoubles
  
  public static final JSONReader.Feature UseBigDecimalForDoubles
  
  Feature that determines whether to deserialize floating-point numbers as BigDecimal when the target type is double. When enabled, double values will be represented with higher precision using BigDecimal.
  By default, this feature is disabled, meaning that standard double precision is used.
  
  Since:
  
  2.0.0
- ErrorOnEnumNotMatch
  
  public static final JSONReader.Feature ErrorOnEnumNotMatch
  
  Feature that determines whether to throw an exception when an enum value in JSON does not match any of the defined enum constants. When enabled, an exception will be thrown if an unknown enum value is encountered.
  By default, this feature is disabled, meaning that unknown enum values are ignored.
  
  Since:
  
  2.0.0
- TrimString
  
  public static final JSONReader.Feature TrimString
  
  Feature that determines whether to trim whitespace from string values during deserialization. When enabled, leading and trailing whitespace will be removed from string values.
  By default, this feature is disabled, meaning that string values are not trimmed.
  
  Since:
  
  2.0.0
- ErrorOnNotSupportAutoType
  
  public static final JSONReader.Feature ErrorOnNotSupportAutoType
  
  Feature that determines whether to throw an exception when autoType is not supported. When enabled, an exception will be thrown if autoType functionality is not available.
  By default, this feature is disabled.
  
  Since:
  
  2.0.0
- DuplicateKeyValueAsArray
  
  public static final JSONReader.Feature DuplicateKeyValueAsArray
  
  Feature that determines how to handle duplicate keys in JSON objects. When enabled, duplicate keys will be stored as arrays rather than overwriting previous values.
  By default, this feature is disabled, meaning that duplicate keys overwrite previous values.
  
  Since:
  
  2.0.0
- AllowUnQuotedFieldNames
  
  public static final JSONReader.Feature AllowUnQuotedFieldNames
  
  Feature that determines whether to allow unquoted field names in JSON. When enabled, field names in JSON objects do not need to be enclosed in quotes.
  By default, this feature is disabled, meaning that field names must be quoted.
  
  Since:
  
  2.0.0
- NonStringKeyAsString
  
  public static final JSONReader.Feature NonStringKeyAsString
  
  Feature that determines whether to treat non-string keys as strings during deserialization. When enabled, keys in JSON objects that are not strings will be converted to string representation.
  By default, this feature is disabled.
  
  Since:
  
  2.0.0
- Base64StringAsByteArray
  
  public static final JSONReader.Feature Base64StringAsByteArray
  
  Feature that determines whether to treat Base64-encoded strings as byte arrays during deserialization. When enabled, strings that contain Base64-encoded data will be automatically decoded to byte arrays.
  By default, this feature is disabled.
  
  Since:
  
  2.0.13
- IgnoreCheckClose
  
  public static final JSONReader.Feature IgnoreCheckClose
  
  Feature that determines whether to ignore checking for resource cleanup. When enabled, the deserializer will not perform checks to ensure proper resource cleanup.
  By default, this feature is disabled.
  
  Since:
  
  2.0.16
- ErrorOnNullForPrimitives
  
  public static final JSONReader.Feature ErrorOnNullForPrimitives
  
  Feature that determines whether to throw an exception when null values are encountered for primitive types during deserialization. When enabled, an exception will be thrown if a null value is found for a primitive type field.
  By default, this feature is disabled, meaning that primitive types are initialized with default values.
  
  Since:
  
  2.0.20
- NullOnError
  
  public static final JSONReader.Feature NullOnError
  
  Feature that determines whether to return null on error during deserialization. When enabled, errors during deserialization will result in null values rather than exceptions.
  By default, this feature is disabled.
  
  Since:
  
  2.0.20
- IgnoreAutoTypeNotMatch
  
  public static final JSONReader.Feature IgnoreAutoTypeNotMatch
  
  Feature that determines whether to ignore autoType mismatches during deserialization. When enabled, mismatches between expected and actual types in autoType scenarios will be ignored.
  By default, this feature is disabled.
  
  Since:
  
  2.0.21
- NonZeroNumberCastToBooleanAsTrue
  
  public static final JSONReader.Feature NonZeroNumberCastToBooleanAsTrue
  
  Feature that determines whether to cast non-zero numbers to boolean true during deserialization. When enabled, any non-zero numeric value will be treated as true when converting to boolean.
  By default, this feature is disabled.
  
  Since:
  
  2.0.24
- IgnoreNullPropertyValue
  
  public static final JSONReader.Feature IgnoreNullPropertyValue
  
  Feature that determines whether to ignore null property values during deserialization. When enabled, properties with null values in JSON will be ignored rather than set to null.
  By default, this feature is disabled.
  
  Since:
  
  2.0.40
- ErrorOnUnknownProperties
  
  public static final JSONReader.Feature ErrorOnUnknownProperties
  
  Feature that determines whether to throw an exception when unknown properties are encountered during deserialization. When enabled, an exception will be thrown if JSON contains properties that do not exist in the target class.
  By default, this feature is disabled, meaning that unknown properties are ignored.
  
  Since:
  
  2.0.42
- EmptyStringAsNull
  
  public static final JSONReader.Feature EmptyStringAsNull
  
  Feature that determines whether to convert empty strings to null values during deserialization. When enabled, empty string values ("") in JSON will be converted to null values.
  By default, this feature is disabled, meaning that empty strings are preserved as empty strings.
  
  Since:
  
  2.0.48
- NonErrorOnNumberOverflow
  
  public static final JSONReader.Feature NonErrorOnNumberOverflow
  
  Feature that determines whether to avoid throwing exceptions on number overflow during deserialization. When enabled, numeric overflow conditions will not cause exceptions to be thrown.
  By default, this feature is disabled, meaning that number overflow will cause exceptions.
  
  Since:
  
  2.0.48
- UseBigIntegerForInts
  
  public static final JSONReader.Feature UseBigIntegerForInts
  
  Feature that determines whether JSON integral (non-floating-point) numbers are to be deserialized into BigIntegers if only generic type description (either Object or Number, or within untyped Map or Collection context) is available. If enabled such values will be deserialized as BigIntegers; if disabled, will be deserialized as "smallest" available type, which is either Integer, Long or BigInteger, depending on number of digits.
  Feature is disabled by default, meaning that "untyped" integral numbers will by default be deserialized using whatever is the most compact integral type, to optimize efficiency.
  
  Since:
  
  2.0.51
- UseLongForInts
  
  public static final JSONReader.Feature UseLongForInts
  
  Feature that determines how "small" JSON integral (non-floating-point) numbers -- ones that fit in 32-bit signed integer (`int`) -- are bound when target type is loosely typed as Object or Number (or within untyped Map or Collection context). If enabled, such values will be deserialized as Long; if disabled, they will be deserialized as "smallest" available type, Integer.
  Note: if UseBigIntegerForInts is enabled, it has precedence over this setting, forcing use of BigInteger for all integral values.
  Feature is disabled by default, meaning that "untyped" integral numbers will by default be deserialized using Integer if value fits.
  
  Since:
  
  2.0.51
- DisableSingleQuote
  
  public static final JSONReader.Feature DisableSingleQuote
  
  Feature that disables the support for single quote. When enabled, single quotes are not allowed as string delimiters in JSON.
  By default, this feature is disabled, meaning that single quotes are supported.
  
  Since:
  
  2.0.53
- UseDoubleForDecimals
  
  public static final JSONReader.Feature UseDoubleForDecimals
  
  Feature that determines whether to deserialize decimal numbers as double values. When enabled, decimal values will be represented as double precision floating-point numbers.
  By default, this feature is disabled.
  
  Since:
  
  2.0.53
- DisableReferenceDetect
  
  public static final JSONReader.Feature DisableReferenceDetect
  
  Feature that disables reference detection during deserialization. When enabled, JSON references (such as those using $ref) will not be processed.
  By default, this feature is disabled, meaning that reference detection is enabled.
  
  Since:
  
  2.0.56
- DisableStringArrayUnwrapping
  
  public static final JSONReader.Feature DisableStringArrayUnwrapping
  
  Feature that determines whether to unwrap single-element string arrays to scalar values. When enabled, JSON arrays containing a single string element will be unwrapped to just that string value rather than returning the array. For example, ["value"] would be returned as "value".
  
  Since:
  
  2.0.60
Field Details
- mask
  
  public final long mask
Method Details
- values
  
  public static JSONReader.Feature[] values()
  
  Returns an array containing the constants of this enum type, in the order they are declared.
  
  Returns:
  
  an array containing the constants of this enum type, in the order they are declared
- valueOf
  
  public static JSONReader.Feature valueOf(String name)
  
  Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
  
  Parameters:
  
  name - the name of the enum constant to be returned.
  
  Returns:
  
  the enum constant with the specified name
  
  Throws:
  
  IllegalArgumentException - if this enum type has no constant with the specified name
  
  NullPointerException - if the argument is null
- of
  
  public static long of(JSONReader.Feature[] features)
  
  Combines the masks of the specified features into a single bitmask.
  
  Parameters:
  
  features - The features to combine
  
  Returns:
  
  A bitmask representing the combined features, or 0 if features is null
- isEnabled
  
  public boolean isEnabled(long features)
  
  Checks if this feature is enabled in the specified features bitmask.
  
  Parameters:
  
  features - The features bitmask to check
  
  Returns:
  
  true if this feature is enabled, false otherwise
- isEnabled
  
  public static boolean isEnabled(long features, JSONReader.Feature feature)
  
  Checks if the specified feature is enabled in the given features bitmask.
  
  Parameters:
  
  features - The features bitmask to check
  
  feature - The feature to check for
  
  Returns:
  
  true if the specified feature is enabled, false otherwise

Enum JSONReader.Feature

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Enum

Enum Constant Summary

Field Summary

Method Summary

Methods inherited from class java.lang.Enum

Methods inherited from class java.lang.Object

Enum Constant Details

FieldBased

IgnoreNoneSerializable

ErrorOnNoneSerializable

SupportArrayToBean

InitStringFieldAsEmpty

SupportAutoType

SupportSmartMatch

UseNativeObject

SupportClassForName

IgnoreSetNullValue

UseDefaultConstructorAsPossible

UseBigDecimalForFloats

UseBigDecimalForDoubles

ErrorOnEnumNotMatch

TrimString

ErrorOnNotSupportAutoType

DuplicateKeyValueAsArray

AllowUnQuotedFieldNames

NonStringKeyAsString

Base64StringAsByteArray

IgnoreCheckClose

ErrorOnNullForPrimitives

NullOnError

IgnoreAutoTypeNotMatch

NonZeroNumberCastToBooleanAsTrue

IgnoreNullPropertyValue

ErrorOnUnknownProperties

EmptyStringAsNull

NonErrorOnNumberOverflow

UseBigIntegerForInts

UseLongForInts

DisableSingleQuote

UseDoubleForDecimals

DisableReferenceDetect

DisableStringArrayUnwrapping

Field Details

mask

Method Details

values

valueOf

of

isEnabled

isEnabled