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.
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.
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 class `sun.misc.Unsafe` (optional)
When this module is present, Gson can use the `Unsafe` class to create instances of classes without no-args constructor.
However, care should be taken when relying on this. `Unsafe` is not available in all environments and its usage has some pitfalls,
see [`GsonBuilder.disableJdkUnsafe()`](https://javadoc.io/doc/com.google.code.gson/gson/latest/com.google.gson/com/google/gson/GsonBuilder.html#disableJdkUnsafe()).
* [User guide](https://github.com/google/gson/blob/master/UserGuide.md): This guide contains examples on how to use Gson in your code.
* [Change log](https://github.com/google/gson/blob/master/CHANGELOG.md): Changes in the recent versions
* [Design document](https://github.com/google/gson/blob/master/GsonDesignDocument.md): 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](https://stackoverflow.com/questions/tagged/gson) or the [google-gson Google group](https://groups.google.com/group/google-gson) to discuss Gson or to post questions.