6b9db2e449
* Add Gson.fromJson(..., TypeToken) overloads
Previously only Gson.fromJson(..., Type) existed which is however not
type-safe since the generic type parameter T used for the return type is
not bound.
Since these methods are often used in the form
gson.fromJson(..., new TypeToken<...>(){}.getType())
this commit now adds overloads which accept a TypeToken and are therefore
more type-safe.
Additional changes:
- Fixed some grammar mistakes
- Added javadoc @see tags
- Consistently write "JSON" in uppercase
- More precise placement of @SuppressWarnings("unchecked")
* Add to Gson.fromJson javadoc that JSON is fully consumed
The newly added documentation deliberately does not state which exception
is thrown because Gson.assertFullConsumption could throw either a
JsonIOException or a JsonSyntaxException.
* Remove unnecessary wrapping and unwrapping as TypeToken in Gson.fromJson
Since the actual implementation of Gson.fromJson is TypeToken based, the
TypeToken variant overloads are now the "main" implementation and the other
overloads delegate to them.
Previously the Type variant overloads were the "main" implementation which
caused `TypeToken.getType()` followed by `TypeToken.get(...)` when the
TypeToken variant overloads were used.
* Trim source code whitespaces
* Fix Gson.fromJson(JsonReader, Class) not casting read Object
To be consistent with the other Gson.fromJson(..., Class) overloads the
method should cast the result.
* Replace User Guide link in Gson documentation
* Remove more references to fromJson(..., Type)
* Extend documentation for fromJson(JsonReader, ...)
* Replace some TypeToken.getType() usages
* Address feedback; improve documentation
* Remove fromJson(JsonReader, Class) again
As noticed during review adding this method is source incompatible.
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| .github | ||
| examples/android-proguard-example | ||
| extras | ||
| gson | ||
| lib | ||
| metrics | ||
| proto | ||
| .gitignore | ||
| CHANGELOG.md | ||
| GsonDesignDocument.md | ||
| LICENSE | ||
| pom.xml | ||
| README.md | ||
| ReleaseProcess.md | ||
| UserGuide.md | ||
Gson
Gson is a Java library that can be used to convert Java Objects into their JSON representation. It can also be used to convert a JSON string to an equivalent Java object. Gson can work with arbitrary Java objects including pre-existing objects that you do not have source-code of.
There are a few open-source projects that can convert Java objects to JSON. However, most of them require that you place Java annotations in your classes; something that you can not do if you do not have access to the source-code. Most also do not fully support the use of Java Generics. Gson considers both of these as very important design goals.
ℹ️ Gson is currently in maintenance mode; existing bugs will be fixed, but large new features will likely not be added. If you want to add a new feature, please first search for existing GitHub issues, or create a new one to discuss the feature and get feedback.
Goals
- Provide simple
toJson()andfromJson()methods to convert Java objects to JSON and vice-versa - Allow pre-existing unmodifiable objects to be converted to and from JSON
- Extensive support of Java Generics
- Allow custom representations for objects
- Support arbitrarily complex objects (with deep inheritance hierarchies and extensive use of generic types)
Download
Gradle:
dependencies {
implementation 'com.google.code.gson:gson:2.9.1'
}
Maven:
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.9.1</version>
</dependency>
Gson jar downloads are available from Maven Central.
Requirements
Minimum Java version
- Gson 2.9.0 and newer: Java 7
- Gson 2.8.9 and older: Java 6
Despite supporting older Java versions, Gson also provides a JPMS module descriptor (module name com.google.gson) for users of Java 9 or newer.
JPMS dependencies (Java 9+)
These are the optional Java Platform Module System (JPMS) JDK modules which Gson depends on. This only applies when running Java 9 or newer.
-
java.sql(optional since Gson 2.8.9)
When this module is present, Gson provides default adapters for some SQL date and time classes. -
jdk.unsupported, respectively classsun.misc.Unsafe(optional)
When this module is present, Gson can use theUnsafeclass to create instances of classes without no-args constructor. However, care should be taken when relying on this.Unsafeis not available in all environments and its usage has some pitfalls, seeGsonBuilder.disableJdkUnsafe().
Documentation
- API Javadoc: Documentation for the current release
- User guide: This guide contains examples on how to use Gson in your code.
- Change log: Changes in the recent versions
- Design document: This document discusses issues we faced while designing Gson. It also includes a comparison of Gson with other Java libraries that can be used for Json conversion
Please use the 'gson' tag on StackOverflow or the google-gson Google group to discuss Gson or to post questions.
Related Content Created by Third Parties
- Gson Tutorial by
StudyTrails - Gson Tutorial Series by
Future Studio - Gson API Report
License
Gson is released under the Apache 2.0 license.
Copyright 2008 Google Inc.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
Disclaimer
This is not an officially supported Google product.