- java.lang.Object
-
- com.google.gson.Gson
-
public final class Gson extends java.lang.Object
This is the main class for using Gson. Gson is typically used by first constructing a Gson instance and then invokingtoJson(Object)
orfromJson(String, Class)
methods on it. Gson instances are Thread-safe so you can reuse them freely across multiple threads.You can create a Gson instance by invoking
new Gson()
if the default configuration is all you need. You can also useGsonBuilder
to build a Gson instance with various configuration options such as versioning support, pretty printing, customJsonSerializer
s,JsonDeserializer
s, andInstanceCreator
s.Here is an example of how Gson is used for a simple Class:
Gson gson = new Gson(); // Or use new GsonBuilder().create(); MyType target = new MyType(); String json = gson.toJson(target); // serializes target to Json MyType target2 = gson.fromJson(json, MyType.class); // deserializes json into target2
If the object that your are serializing/deserializing is a
ParameterizedType
(i.e. contains at least one type parameter and may be an array) then you must use thetoJson(Object, Type)
orfromJson(String, Type)
method. Here is an example for serializing and deserializing aParameterizedType
:Type listType = new TypeToken<List<String>>() {}.getType(); List<String> target = new LinkedList<String>(); target.add("blah"); Gson gson = new Gson(); String json = gson.toJson(target, listType); List<String> target2 = gson.fromJson(json, listType);
See the Gson User Guide for a more complete set of examples.
Lenient JSON handling
For legacy reasons most of theGson
methods allow JSON data which does not comply with the JSON specification, regardless of whetherGsonBuilder.setLenient()
is used or not. If this behavior is not desired, the following workarounds can be used:Serialization
- Use
getAdapter(Class)
to obtain the adapter for the type to be serialized - When using an existing
JsonWriter
, manually apply the writer settings of thisGson
instance listed bynewJsonWriter(Writer)
.
Otherwise, when not using an existingJsonWriter
, usenewJsonWriter(Writer)
to construct one. - Call
TypeAdapter.write(JsonWriter, Object)
Deserialization
- Use
getAdapter(Class)
to obtain the adapter for the type to be deserialized - When using an existing
JsonReader
, manually apply the reader settings of thisGson
instance listed bynewJsonReader(Reader)
.
Otherwise, when not using an existingJsonReader
, usenewJsonReader(Reader)
to construct one. - Call
TypeAdapter.read(JsonReader)
- Call
JsonReader.peek()
and verify that the result isJsonToken.END_DOCUMENT
to make sure there is no trailing data
- See Also:
TypeToken
- Use
-
-
Nested Class Summary
Nested Classes Modifier and Type Class Description (package private) static class
Gson.FutureTypeAdapter<T>
-
Field Summary
Fields Modifier and Type Field Description (package private) java.util.List<TypeAdapterFactory>
builderFactories
(package private) java.util.List<TypeAdapterFactory>
builderHierarchyFactories
private java.lang.ThreadLocal<java.util.Map<TypeToken<?>,Gson.FutureTypeAdapter<?>>>
calls
This thread local guards against reentrant calls to getAdapter().(package private) boolean
complexMapKeySerialization
private ConstructorConstructor
constructorConstructor
(package private) java.lang.String
datePattern
(package private) int
dateStyle
(package private) static boolean
DEFAULT_COMPLEX_MAP_KEYS
(package private) static java.lang.String
DEFAULT_DATE_PATTERN
(package private) static boolean
DEFAULT_ESCAPE_HTML
(package private) static FieldNamingStrategy
DEFAULT_FIELD_NAMING_STRATEGY
(package private) static boolean
DEFAULT_JSON_NON_EXECUTABLE
(package private) static boolean
DEFAULT_LENIENT
(package private) static ToNumberStrategy
DEFAULT_NUMBER_TO_NUMBER_STRATEGY
(package private) static ToNumberStrategy
DEFAULT_OBJECT_TO_NUMBER_STRATEGY
(package private) static boolean
DEFAULT_PRETTY_PRINT
(package private) static boolean
DEFAULT_SERIALIZE_NULLS
(package private) static boolean
DEFAULT_SPECIALIZE_FLOAT_VALUES
(package private) static boolean
DEFAULT_USE_JDK_UNSAFE
(package private) Excluder
excluder
(package private) java.util.List<TypeAdapterFactory>
factories
(package private) FieldNamingStrategy
fieldNamingStrategy
(package private) boolean
generateNonExecutableJson
(package private) boolean
htmlSafe
(package private) java.util.Map<java.lang.reflect.Type,InstanceCreator<?>>
instanceCreators
private static java.lang.String
JSON_NON_EXECUTABLE_PREFIX
private JsonAdapterAnnotationTypeAdapterFactory
jsonAdapterFactory
(package private) boolean
lenient
(package private) LongSerializationPolicy
longSerializationPolicy
private static TypeToken<?>
NULL_KEY_SURROGATE
(package private) ToNumberStrategy
numberToNumberStrategy
(package private) ToNumberStrategy
objectToNumberStrategy
(package private) boolean
prettyPrinting
(package private) java.util.List<ReflectionAccessFilter>
reflectionFilters
(package private) boolean
serializeNulls
(package private) boolean
serializeSpecialFloatingPointValues
(package private) int
timeStyle
private java.util.Map<TypeToken<?>,TypeAdapter<?>>
typeTokenCache
(package private) boolean
useJdkUnsafe
-
Constructor Summary
Constructors Constructor Description Gson()
Constructs a Gson object with default configuration.Gson(Excluder excluder, FieldNamingStrategy fieldNamingStrategy, java.util.Map<java.lang.reflect.Type,InstanceCreator<?>> instanceCreators, boolean serializeNulls, boolean complexMapKeySerialization, boolean generateNonExecutableGson, boolean htmlSafe, boolean prettyPrinting, boolean lenient, boolean serializeSpecialFloatingPointValues, boolean useJdkUnsafe, LongSerializationPolicy longSerializationPolicy, java.lang.String datePattern, int dateStyle, int timeStyle, java.util.List<TypeAdapterFactory> builderFactories, java.util.List<TypeAdapterFactory> builderHierarchyFactories, java.util.List<TypeAdapterFactory> factoriesToBeAdded, ToNumberStrategy objectToNumberStrategy, ToNumberStrategy numberToNumberStrategy, java.util.List<ReflectionAccessFilter> reflectionFilters)
-
Method Summary
All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods Modifier and Type Method Description private static void
assertFullConsumption(java.lang.Object obj, JsonReader reader)
private static TypeAdapter<java.util.concurrent.atomic.AtomicLong>
atomicLongAdapter(TypeAdapter<java.lang.Number> longAdapter)
private static TypeAdapter<java.util.concurrent.atomic.AtomicLongArray>
atomicLongArrayAdapter(TypeAdapter<java.lang.Number> longAdapter)
(package private) static void
checkValidFloatingPoint(double value)
private TypeAdapter<java.lang.Number>
doubleAdapter(boolean serializeSpecialFloatingPointValues)
Excluder
excluder()
Deprecated.This method by accident exposes an internal Gson class; it might be removed in a future version.FieldNamingStrategy
fieldNamingStrategy()
Returns the field naming strategy used by this Gson instance.private TypeAdapter<java.lang.Number>
floatAdapter(boolean serializeSpecialFloatingPointValues)
<T> T
fromJson(JsonElement json, java.lang.Class<T> classOfT)
This method deserializes the Json read from the specified parse tree into an object of the specified type.<T> T
fromJson(JsonElement json, java.lang.reflect.Type typeOfT)
This method deserializes the Json read from the specified parse tree into an object of the specified type.<T> T
fromJson(JsonReader reader, java.lang.reflect.Type typeOfT)
Reads the next JSON value fromreader
and convert it to an object of typetypeOfT
.<T> T
fromJson(java.io.Reader json, java.lang.Class<T> classOfT)
This method deserializes the Json read from the specified reader into an object of the specified class.<T> T
fromJson(java.io.Reader json, java.lang.reflect.Type typeOfT)
This method deserializes the Json read from the specified reader into an object of the specified type.<T> T
fromJson(java.lang.String json, java.lang.Class<T> classOfT)
This method deserializes the specified Json into an object of the specified class.<T> T
fromJson(java.lang.String json, java.lang.reflect.Type typeOfT)
This method deserializes the specified Json into an object of the specified type.<T> TypeAdapter<T>
getAdapter(TypeToken<T> type)
Returns the type adapter for type.<T> TypeAdapter<T>
getAdapter(java.lang.Class<T> type)
Returns the type adapter for type.<T> TypeAdapter<T>
getDelegateAdapter(TypeAdapterFactory skipPast, TypeToken<T> type)
This method is used to get an alternate type adapter for the specified type.boolean
htmlSafe()
Returns whether this Gson instance produces JSON output which is HTML-safe, that means all HTML characters are escaped.private static TypeAdapter<java.lang.Number>
longAdapter(LongSerializationPolicy longSerializationPolicy)
GsonBuilder
newBuilder()
Returns a new GsonBuilder containing all custom factories and configuration used by the current instance.JsonReader
newJsonReader(java.io.Reader reader)
Returns a new JSON reader configured for the settings on this Gson instance.JsonWriter
newJsonWriter(java.io.Writer writer)
Returns a new JSON writer configured for the settings on this Gson instance.boolean
serializeNulls()
Returns whether this Gson instance is serializing JSON object properties withnull
values, or just omits them.java.lang.String
toJson(JsonElement jsonElement)
Converts a tree ofJsonElement
s into its equivalent JSON representation.void
toJson(JsonElement jsonElement, JsonWriter writer)
Writes the JSON forjsonElement
towriter
.void
toJson(JsonElement jsonElement, java.lang.Appendable writer)
Writes out the equivalent JSON for a tree ofJsonElement
s.java.lang.String
toJson(java.lang.Object src)
This method serializes the specified object into its equivalent Json representation.void
toJson(java.lang.Object src, java.lang.Appendable writer)
This method serializes the specified object into its equivalent Json representation.java.lang.String
toJson(java.lang.Object src, java.lang.reflect.Type typeOfSrc)
This method serializes the specified object, including those of generic types, into its equivalent Json representation.void
toJson(java.lang.Object src, java.lang.reflect.Type typeOfSrc, JsonWriter writer)
Writes the JSON representation ofsrc
of typetypeOfSrc
towriter
.void
toJson(java.lang.Object src, java.lang.reflect.Type typeOfSrc, java.lang.Appendable writer)
This method serializes the specified object, including those of generic types, into its equivalent Json representation.JsonElement
toJsonTree(java.lang.Object src)
This method serializes the specified object into its equivalent representation as a tree ofJsonElement
s.JsonElement
toJsonTree(java.lang.Object src, java.lang.reflect.Type typeOfSrc)
This method serializes the specified object, including those of generic types, into its equivalent representation as a tree ofJsonElement
s.java.lang.String
toString()
-
-
-
Field Detail
-
DEFAULT_JSON_NON_EXECUTABLE
static final boolean DEFAULT_JSON_NON_EXECUTABLE
- See Also:
- Constant Field Values
-
DEFAULT_LENIENT
static final boolean DEFAULT_LENIENT
- See Also:
- Constant Field Values
-
DEFAULT_PRETTY_PRINT
static final boolean DEFAULT_PRETTY_PRINT
- See Also:
- Constant Field Values
-
DEFAULT_ESCAPE_HTML
static final boolean DEFAULT_ESCAPE_HTML
- See Also:
- Constant Field Values
-
DEFAULT_SERIALIZE_NULLS
static final boolean DEFAULT_SERIALIZE_NULLS
- See Also:
- Constant Field Values
-
DEFAULT_COMPLEX_MAP_KEYS
static final boolean DEFAULT_COMPLEX_MAP_KEYS
- See Also:
- Constant Field Values
-
DEFAULT_SPECIALIZE_FLOAT_VALUES
static final boolean DEFAULT_SPECIALIZE_FLOAT_VALUES
- See Also:
- Constant Field Values
-
DEFAULT_USE_JDK_UNSAFE
static final boolean DEFAULT_USE_JDK_UNSAFE
- See Also:
- Constant Field Values
-
DEFAULT_DATE_PATTERN
static final java.lang.String DEFAULT_DATE_PATTERN
-
DEFAULT_FIELD_NAMING_STRATEGY
static final FieldNamingStrategy DEFAULT_FIELD_NAMING_STRATEGY
-
DEFAULT_OBJECT_TO_NUMBER_STRATEGY
static final ToNumberStrategy DEFAULT_OBJECT_TO_NUMBER_STRATEGY
-
DEFAULT_NUMBER_TO_NUMBER_STRATEGY
static final ToNumberStrategy DEFAULT_NUMBER_TO_NUMBER_STRATEGY
-
NULL_KEY_SURROGATE
private static final TypeToken<?> NULL_KEY_SURROGATE
-
JSON_NON_EXECUTABLE_PREFIX
private static final java.lang.String JSON_NON_EXECUTABLE_PREFIX
- See Also:
- Constant Field Values
-
calls
private final java.lang.ThreadLocal<java.util.Map<TypeToken<?>,Gson.FutureTypeAdapter<?>>> calls
This thread local guards against reentrant calls to getAdapter(). In certain object graphs, creating an adapter for a type may recursively require an adapter for the same type! Without intervention, the recursive lookup would stack overflow. We cheat by returning a proxy type adapter. The proxy is wired up once the initial adapter has been created.
-
typeTokenCache
private final java.util.Map<TypeToken<?>,TypeAdapter<?>> typeTokenCache
-
constructorConstructor
private final ConstructorConstructor constructorConstructor
-
jsonAdapterFactory
private final JsonAdapterAnnotationTypeAdapterFactory jsonAdapterFactory
-
factories
final java.util.List<TypeAdapterFactory> factories
-
excluder
final Excluder excluder
-
fieldNamingStrategy
final FieldNamingStrategy fieldNamingStrategy
-
instanceCreators
final java.util.Map<java.lang.reflect.Type,InstanceCreator<?>> instanceCreators
-
serializeNulls
final boolean serializeNulls
-
complexMapKeySerialization
final boolean complexMapKeySerialization
-
generateNonExecutableJson
final boolean generateNonExecutableJson
-
htmlSafe
final boolean htmlSafe
-
prettyPrinting
final boolean prettyPrinting
-
lenient
final boolean lenient
-
serializeSpecialFloatingPointValues
final boolean serializeSpecialFloatingPointValues
-
useJdkUnsafe
final boolean useJdkUnsafe
-
datePattern
final java.lang.String datePattern
-
dateStyle
final int dateStyle
-
timeStyle
final int timeStyle
-
longSerializationPolicy
final LongSerializationPolicy longSerializationPolicy
-
builderFactories
final java.util.List<TypeAdapterFactory> builderFactories
-
builderHierarchyFactories
final java.util.List<TypeAdapterFactory> builderHierarchyFactories
-
objectToNumberStrategy
final ToNumberStrategy objectToNumberStrategy
-
numberToNumberStrategy
final ToNumberStrategy numberToNumberStrategy
-
reflectionFilters
final java.util.List<ReflectionAccessFilter> reflectionFilters
-
-
Constructor Detail
-
Gson
public Gson()
Constructs a Gson object with default configuration. The default configuration has the following settings:- The JSON generated by
toJson
methods is in compact representation. This means that all the unneeded white-space is removed. You can change this behavior withGsonBuilder.setPrettyPrinting()
. - The generated JSON omits all the fields that are null. Note that nulls in arrays are
kept as is since an array is an ordered list. Moreover, if a field is not null, but its
generated JSON is empty, the field is kept. You can configure Gson to serialize null values
by setting
GsonBuilder.serializeNulls()
. - Gson provides default serialization and deserialization for Enums,
Map
,URL
,URI
,Locale
,Date
,BigDecimal
, andBigInteger
classes. If you would prefer to change the default representation, you can do so by registering a type adapter throughGsonBuilder.registerTypeAdapter(Type, Object)
. - The default Date format is same as
DateFormat.DEFAULT
. This format ignores the millisecond portion of the date during serialization. You can change this by invokingGsonBuilder.setDateFormat(int)
orGsonBuilder.setDateFormat(String)
. - By default, Gson ignores the
Expose
annotation. You can enable Gson to serialize/deserialize only those fields marked with this annotation throughGsonBuilder.excludeFieldsWithoutExposeAnnotation()
. - By default, Gson ignores the
Since
annotation. You can enable Gson to use this annotation throughGsonBuilder.setVersion(double)
. - The default field naming policy for the output Json is same as in Java. So, a Java class
field
versionNumber
will be output as"versionNumber"
in Json. The same rules are applied for mapping incoming Json to the Java classes. You can change this policy throughGsonBuilder.setFieldNamingPolicy(FieldNamingPolicy)
. - By default, Gson excludes
transient
orstatic
fields from consideration for serialization and deserialization. You can change this behavior throughGsonBuilder.excludeFieldsWithModifiers(int...)
.
- The JSON generated by
-
Gson
Gson(Excluder excluder, FieldNamingStrategy fieldNamingStrategy, java.util.Map<java.lang.reflect.Type,InstanceCreator<?>> instanceCreators, boolean serializeNulls, boolean complexMapKeySerialization, boolean generateNonExecutableGson, boolean htmlSafe, boolean prettyPrinting, boolean lenient, boolean serializeSpecialFloatingPointValues, boolean useJdkUnsafe, LongSerializationPolicy longSerializationPolicy, java.lang.String datePattern, int dateStyle, int timeStyle, java.util.List<TypeAdapterFactory> builderFactories, java.util.List<TypeAdapterFactory> builderHierarchyFactories, java.util.List<TypeAdapterFactory> factoriesToBeAdded, ToNumberStrategy objectToNumberStrategy, ToNumberStrategy numberToNumberStrategy, java.util.List<ReflectionAccessFilter> reflectionFilters)
-
-
Method Detail
-
newBuilder
public GsonBuilder newBuilder()
Returns a new GsonBuilder containing all custom factories and configuration used by the current instance.- Returns:
- a GsonBuilder instance.
-
excluder
@Deprecated public Excluder excluder()
Deprecated.This method by accident exposes an internal Gson class; it might be removed in a future version.
-
fieldNamingStrategy
public FieldNamingStrategy fieldNamingStrategy()
Returns the field naming strategy used by this Gson instance.
-
serializeNulls
public boolean serializeNulls()
Returns whether this Gson instance is serializing JSON object properties withnull
values, or just omits them.- See Also:
GsonBuilder.serializeNulls()
-
htmlSafe
public boolean htmlSafe()
Returns whether this Gson instance produces JSON output which is HTML-safe, that means all HTML characters are escaped.- See Also:
GsonBuilder.disableHtmlEscaping()
-
doubleAdapter
private TypeAdapter<java.lang.Number> doubleAdapter(boolean serializeSpecialFloatingPointValues)
-
floatAdapter
private TypeAdapter<java.lang.Number> floatAdapter(boolean serializeSpecialFloatingPointValues)
-
checkValidFloatingPoint
static void checkValidFloatingPoint(double value)
-
longAdapter
private static TypeAdapter<java.lang.Number> longAdapter(LongSerializationPolicy longSerializationPolicy)
-
atomicLongAdapter
private static TypeAdapter<java.util.concurrent.atomic.AtomicLong> atomicLongAdapter(TypeAdapter<java.lang.Number> longAdapter)
-
atomicLongArrayAdapter
private static TypeAdapter<java.util.concurrent.atomic.AtomicLongArray> atomicLongArrayAdapter(TypeAdapter<java.lang.Number> longAdapter)
-
getAdapter
public <T> TypeAdapter<T> getAdapter(TypeToken<T> type)
Returns the type adapter for type.- Throws:
java.lang.IllegalArgumentException
- if this GSON cannot serialize and deserializetype
.
-
getDelegateAdapter
public <T> TypeAdapter<T> getDelegateAdapter(TypeAdapterFactory skipPast, TypeToken<T> type)
This method is used to get an alternate type adapter for the specified type. This is used to access a type adapter that is overridden by aTypeAdapterFactory
that you may have registered. This features is typically used when you want to register a type adapter that does a little bit of work but then delegates further processing to the Gson default type adapter. Here is an example:Let's say we want to write a type adapter that counts the number of objects being read from or written to JSON. We can achieve this by writing a type adapter factory that uses the
getDelegateAdapter
method:class StatsTypeAdapterFactory implements TypeAdapterFactory { public int numReads = 0; public int numWrites = 0; public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) { final TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type); return new TypeAdapter<T>() { public void write(JsonWriter out, T value) throws IOException { ++numWrites; delegate.write(out, value); } public T read(JsonReader in) throws IOException { ++numReads; return delegate.read(in); } }; } }
StatsTypeAdapterFactory stats = new StatsTypeAdapterFactory(); Gson gson = new GsonBuilder().registerTypeAdapterFactory(stats).create(); // Call gson.toJson() and fromJson methods on objects System.out.println("Num JSON reads" + stats.numReads); System.out.println("Num JSON writes" + stats.numWrites);
skipPast
. In case of multiple TypeAdapterFactories registered it is up to the caller of this function to insure that the order of registration does not prevent this method from reaching a factory they would expect to reply from this call. Note that since you can not override type adapter factories for String and Java primitive types, our stats factory will not count the number of String or primitives that will be read or written.- Parameters:
skipPast
- The type adapter factory that needs to be skipped while searching for a matching type adapter. In most cases, you should just pass this (the type adapter factory from wheregetDelegateAdapter
method is being invoked).type
- Type for which the delegate adapter is being searched for.- Since:
- 2.2
-
getAdapter
public <T> TypeAdapter<T> getAdapter(java.lang.Class<T> type)
Returns the type adapter for type.- Throws:
java.lang.IllegalArgumentException
- if this GSON cannot serialize and deserializetype
.
-
toJsonTree
public JsonElement toJsonTree(java.lang.Object src)
This method serializes the specified object into its equivalent representation as a tree ofJsonElement
s. This method should be used when the specified object is not a generic type. This method usesObject.getClass()
to get the type for the specified object, but thegetClass()
loses the generic type information because of the Type Erasure feature of Java. Note that this method works fine if the any of the object fields are of generic type, just the object itself should not be of a generic type. If the object is of generic type, usetoJsonTree(Object, Type)
instead.- Parameters:
src
- the object for which Json representation is to be created setting for Gson- Returns:
- Json representation of
src
. - Since:
- 1.4
-
toJsonTree
public JsonElement toJsonTree(java.lang.Object src, java.lang.reflect.Type typeOfSrc)
This method serializes the specified object, including those of generic types, into its equivalent representation as a tree ofJsonElement
s. This method must be used if the specified object is a generic type. For non-generic objects, usetoJsonTree(Object)
instead.- Parameters:
src
- the object for which JSON representation is to be createdtypeOfSrc
- The specific genericized type of src. You can obtain this type by using theTypeToken
class. For example, to get the type forCollection<Foo>
, you should use:Type typeOfSrc = new TypeToken<Collection<Foo>>(){}.getType();
- Returns:
- Json representation of
src
- Since:
- 1.4
-
toJson
public java.lang.String toJson(java.lang.Object src)
This method serializes the specified object into its equivalent Json representation. This method should be used when the specified object is not a generic type. This method usesObject.getClass()
to get the type for the specified object, but thegetClass()
loses the generic type information because of the Type Erasure feature of Java. Note that this method works fine if the any of the object fields are of generic type, just the object itself should not be of a generic type. If the object is of generic type, usetoJson(Object, Type)
instead. If you want to write out the object to aWriter
, usetoJson(Object, Appendable)
instead.- Parameters:
src
- the object for which Json representation is to be created setting for Gson- Returns:
- Json representation of
src
.
-
toJson
public java.lang.String toJson(java.lang.Object src, java.lang.reflect.Type typeOfSrc)
This method serializes the specified object, including those of generic types, into its equivalent Json representation. This method must be used if the specified object is a generic type. For non-generic objects, usetoJson(Object)
instead. If you want to write out the object to aAppendable
, usetoJson(Object, Type, Appendable)
instead.- Parameters:
src
- the object for which JSON representation is to be createdtypeOfSrc
- The specific genericized type of src. You can obtain this type by using theTypeToken
class. For example, to get the type forCollection<Foo>
, you should use:Type typeOfSrc = new TypeToken<Collection<Foo>>(){}.getType();
- Returns:
- Json representation of
src
-
toJson
public void toJson(java.lang.Object src, java.lang.Appendable writer) throws JsonIOException
This method serializes the specified object into its equivalent Json representation. This method should be used when the specified object is not a generic type. This method usesObject.getClass()
to get the type for the specified object, but thegetClass()
loses the generic type information because of the Type Erasure feature of Java. Note that this method works fine if the any of the object fields are of generic type, just the object itself should not be of a generic type. If the object is of generic type, usetoJson(Object, Type, Appendable)
instead.- Parameters:
src
- the object for which Json representation is to be created setting for Gsonwriter
- Writer to which the Json representation needs to be written- Throws:
JsonIOException
- if there was a problem writing to the writer- Since:
- 1.2
-
toJson
public void toJson(java.lang.Object src, java.lang.reflect.Type typeOfSrc, java.lang.Appendable writer) throws JsonIOException
This method serializes the specified object, including those of generic types, into its equivalent Json representation. This method must be used if the specified object is a generic type. For non-generic objects, usetoJson(Object, Appendable)
instead.- Parameters:
src
- the object for which JSON representation is to be createdtypeOfSrc
- The specific genericized type of src. You can obtain this type by using theTypeToken
class. For example, to get the type forCollection<Foo>
, you should use:Type typeOfSrc = new TypeToken<Collection<Foo>>(){}.getType();
writer
- Writer to which the Json representation of src needs to be written.- Throws:
JsonIOException
- if there was a problem writing to the writer- Since:
- 1.2
-
toJson
public void toJson(java.lang.Object src, java.lang.reflect.Type typeOfSrc, JsonWriter writer) throws JsonIOException
Writes the JSON representation ofsrc
of typetypeOfSrc
towriter
.The JSON data is written in lenient mode, regardless of the lenient mode setting of the provided writer. The lenient mode setting of the writer is restored once this method returns.
The 'HTML-safe' and 'serialize
null
' settings of thisGson
instance (configured by theGsonBuilder
) are applied, and the original settings of the writer are restored once this method returns.- Throws:
JsonIOException
- if there was a problem writing to the writer
-
toJson
public java.lang.String toJson(JsonElement jsonElement)
Converts a tree ofJsonElement
s into its equivalent JSON representation.- Parameters:
jsonElement
- root of a tree ofJsonElement
s- Returns:
- JSON String representation of the tree
- Since:
- 1.4
-
toJson
public void toJson(JsonElement jsonElement, java.lang.Appendable writer) throws JsonIOException
Writes out the equivalent JSON for a tree ofJsonElement
s.- Parameters:
jsonElement
- root of a tree ofJsonElement
swriter
- Writer to which the Json representation needs to be written- Throws:
JsonIOException
- if there was a problem writing to the writer- Since:
- 1.4
-
newJsonWriter
public JsonWriter newJsonWriter(java.io.Writer writer) throws java.io.IOException
Returns a new JSON writer configured for the settings on this Gson instance.The following settings are considered:
- Throws:
java.io.IOException
-
newJsonReader
public JsonReader newJsonReader(java.io.Reader reader)
Returns a new JSON reader configured for the settings on this Gson instance.The following settings are considered:
-
toJson
public void toJson(JsonElement jsonElement, JsonWriter writer) throws JsonIOException
Writes the JSON forjsonElement
towriter
.The JSON data is written in lenient mode, regardless of the lenient mode setting of the provided writer. The lenient mode setting of the writer is restored once this method returns.
The 'HTML-safe' and 'serialize
null
' settings of thisGson
instance (configured by theGsonBuilder
) are applied, and the original settings of the writer are restored once this method returns.- Throws:
JsonIOException
- if there was a problem writing to the writer
-
fromJson
public <T> T fromJson(java.lang.String json, java.lang.Class<T> classOfT) throws JsonSyntaxException
This method deserializes the specified Json into an object of the specified class. It is not suitable to use if the specified class is a generic type since it will not have the generic type information because of the Type Erasure feature of Java. Therefore, this method should not be used if the desired type is a generic type. Note that this method works fine if the any of the fields of the specified object are generics, just the object itself should not be a generic type. For the cases when the object is of generic type, invokefromJson(String, Type)
. If you have the Json in aReader
instead of a String, usefromJson(Reader, Class)
instead.An exception is thrown if the JSON string has multiple top-level JSON elements, or if there is trailing data.
- Type Parameters:
T
- the type of the desired object- Parameters:
json
- the string from which the object is to be deserializedclassOfT
- the class of T- Returns:
- an object of type T from the string. Returns
null
ifjson
isnull
or ifjson
is empty. - Throws:
JsonSyntaxException
- if json is not a valid representation for an object of type classOfT
-
fromJson
public <T> T fromJson(java.lang.String json, java.lang.reflect.Type typeOfT) throws JsonSyntaxException
This method deserializes the specified Json into an object of the specified type. This method is useful if the specified object is a generic type. For non-generic objects, usefromJson(String, Class)
instead. If you have the Json in aReader
instead of a String, usefromJson(Reader, Type)
instead.An exception is thrown if the JSON string has multiple top-level JSON elements, or if there is trailing data.
- Type Parameters:
T
- the type of the desired object- Parameters:
json
- the string from which the object is to be deserializedtypeOfT
- The specific genericized type of src. You can obtain this type by using theTypeToken
class. For example, to get the type forCollection<Foo>
, you should use:Type typeOfT = new TypeToken<Collection<Foo>>(){}.getType();
- Returns:
- an object of type T from the string. Returns
null
ifjson
isnull
or ifjson
is empty. - Throws:
JsonParseException
- if json is not a valid representation for an object of type typeOfTJsonSyntaxException
- if json is not a valid representation for an object of type
-
fromJson
public <T> T fromJson(java.io.Reader json, java.lang.Class<T> classOfT) throws JsonSyntaxException, JsonIOException
This method deserializes the Json read from the specified reader into an object of the specified class. It is not suitable to use if the specified class is a generic type since it will not have the generic type information because of the Type Erasure feature of Java. Therefore, this method should not be used if the desired type is a generic type. Note that this method works fine if the any of the fields of the specified object are generics, just the object itself should not be a generic type. For the cases when the object is of generic type, invokefromJson(Reader, Type)
. If you have the Json in a String form instead of aReader
, usefromJson(String, Class)
instead.An exception is thrown if the JSON data has multiple top-level JSON elements, or if there is trailing data.
- Type Parameters:
T
- the type of the desired object- Parameters:
json
- the reader producing the Json from which the object is to be deserialized.classOfT
- the class of T- Returns:
- an object of type T from the string. Returns
null
ifjson
is at EOF. - Throws:
JsonIOException
- if there was a problem reading from the ReaderJsonSyntaxException
- if json is not a valid representation for an object of type- Since:
- 1.2
-
fromJson
public <T> T fromJson(java.io.Reader json, java.lang.reflect.Type typeOfT) throws JsonIOException, JsonSyntaxException
This method deserializes the Json read from the specified reader into an object of the specified type. This method is useful if the specified object is a generic type. For non-generic objects, usefromJson(Reader, Class)
instead. If you have the Json in a String form instead of aReader
, usefromJson(String, Type)
instead.An exception is thrown if the JSON data has multiple top-level JSON elements, or if there is trailing data.
- Type Parameters:
T
- the type of the desired object- Parameters:
json
- the reader producing Json from which the object is to be deserializedtypeOfT
- The specific genericized type of src. You can obtain this type by using theTypeToken
class. For example, to get the type forCollection<Foo>
, you should use:Type typeOfT = new TypeToken<Collection<Foo>>(){}.getType();
- Returns:
- an object of type T from the json. Returns
null
ifjson
is at EOF. - Throws:
JsonIOException
- if there was a problem reading from the ReaderJsonSyntaxException
- if json is not a valid representation for an object of type- Since:
- 1.2
-
assertFullConsumption
private static void assertFullConsumption(java.lang.Object obj, JsonReader reader)
-
fromJson
public <T> T fromJson(JsonReader reader, java.lang.reflect.Type typeOfT) throws JsonIOException, JsonSyntaxException
Reads the next JSON value fromreader
and convert it to an object of typetypeOfT
. Returnsnull
, if thereader
is at EOF. Since Type is not parameterized by T, this method is type unsafe and should be used carefully.Unlike the other
fromJson
methods, no exception is thrown if the JSON data has multiple top-level JSON elements, or if there is trailing data.The JSON data is parsed in lenient mode, regardless of the lenient mode setting of the provided reader. The lenient mode setting of the reader is restored once this method returns.
- Throws:
JsonIOException
- if there was a problem writing to the ReaderJsonSyntaxException
- if json is not a valid representation for an object of type
-
fromJson
public <T> T fromJson(JsonElement json, java.lang.Class<T> classOfT) throws JsonSyntaxException
This method deserializes the Json read from the specified parse tree into an object of the specified type. It is not suitable to use if the specified class is a generic type since it will not have the generic type information because of the Type Erasure feature of Java. Therefore, this method should not be used if the desired type is a generic type. Note that this method works fine if the any of the fields of the specified object are generics, just the object itself should not be a generic type. For the cases when the object is of generic type, invokefromJson(JsonElement, Type)
.- Type Parameters:
T
- the type of the desired object- Parameters:
json
- the root of the parse tree ofJsonElement
s from which the object is to be deserializedclassOfT
- The class of T- Returns:
- an object of type T from the json. Returns
null
ifjson
isnull
or ifjson
is empty. - Throws:
JsonSyntaxException
- if json is not a valid representation for an object of type typeOfT- Since:
- 1.3
-
fromJson
public <T> T fromJson(JsonElement json, java.lang.reflect.Type typeOfT) throws JsonSyntaxException
This method deserializes the Json read from the specified parse tree into an object of the specified type. This method is useful if the specified object is a generic type. For non-generic objects, usefromJson(JsonElement, Class)
instead.- Type Parameters:
T
- the type of the desired object- Parameters:
json
- the root of the parse tree ofJsonElement
s from which the object is to be deserializedtypeOfT
- The specific genericized type of src. You can obtain this type by using theTypeToken
class. For example, to get the type forCollection<Foo>
, you should use:Type typeOfT = new TypeToken<Collection<Foo>>(){}.getType();
- Returns:
- an object of type T from the json. Returns
null
ifjson
isnull
or ifjson
is empty. - Throws:
JsonSyntaxException
- if json is not a valid representation for an object of type typeOfT- Since:
- 1.3
-
toString
public java.lang.String toString()
- Overrides:
toString
in classjava.lang.Object
-
-