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1. Overview

Working with JSON data in Java can be easy, but – like most anything in Java – there are a lot of options and libraries we can chose from.

This guide should make that choice easier and should give you a solid understanding of the ecosystem right now. We’ll discuss the most common JSON processing libraries in Java:

We’re following a simple structure for each library – first some useful resources to get started (both here on Baeldung as well as external). Then we’re going to go over a basic code example, just to see how working with the library actually looks like.

2. Popularity and Basic Stats

First, let’s start with some statistics as a proxy for the popularity of each library:

2.1. Jackson

2.2. Gson

  • Maven Usage: 1588
  • Github Stars: 2079
  • Github Forks: 471

2.3. json-io

2.4. Genson

3. Jackson

Next, let’s have a look at the most popular of these – Jackson. Jackson is a multi-purpose Java library for processing JSON data.

3.1. Useful Resources

Here are some official resources for the library:

On Baeldung:

Other Interesting Writeups:

3.2. Maven Dependency

To use the library – here’s the Maven dependency to add into your pom.xml:

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>${jackson.version}</version>
</dependency>

Note that the latest version of Jackson right now is 2.6.3.

3.3. Simple Example with Jackson

Now, let’s see how to use Jackson in a simple example:

@Test
public void whenSerializeAndDeserializeUsingJackson_thenCorrect() 
  throws IOException{
    Foo foo = new Foo(1,"first");
    ObjectMapper mapper = new ObjectMapper();

    String jsonStr = mapper.writeValueAsString(foo);
    Foo result = mapper.readValue(jsonStr, Foo.class);
    assertEquals(foo.getId(),result.getId());
}

Note that:

  • ObjectMapper.writeValueAsString() is used to serialize Object to JSON string.
  • ObjectMapper.readValue() is used to deserialize JSON string to Java Object.
  • Sample JSON output:
{
    "id":1,
    "name":"first"
}

4. Gson

Gson is the next Java JSON library that we’re going to be looking at.

4.1. Useful Resources

Here are some official resources for the library:

On Baeldung:

Other Interesting Writeups:

4.2. Maven Dependency

<dependency>
    <groupId>com.google.code.gson</groupId>
    <artifactId>gson</artifactId>
    <version>${gson.version}</version>
</dependency>

Note that the latest version of Gson right now is 2.4.

4.3. Simple Example with Gson

Here is a simple example clarify how to use Gson to serialize/desrialize JSON:

@Test
public void whenSerializeAndDeserializeUsingGson_thenCorrect(){
    Gson gson = new Gson();
    Foo foo = new Foo(1,"first");

    String jsonStr = gson.toJson(foo);
    Foo result = gson.fromJson(jsonStr, Foo.class);
    assertEquals(foo.getId(),result.getId());
}

Note that:

  • Gson.toJson() is used to serialize Object to JSON
  • Gson.fromJson() is used to desrialize JSON to Java Object

5. Json-io

Json-io is a simple Java library to serialize/deserialize JSON.

5.1. Useful Resources

Here are some official resources for the library:

5.2. Maven Dependency

<dependency>
    <groupId>com.cedarsoftware</groupId>
    <artifactId>json-io</artifactId>
    <version>${json-io.version}</version>
</dependency>

Note that the latest version of json-io right now is 4.1.9.

5.3. Simple Example with json-io

Now, let’s take a look at a simple example of using json-io:

@Test
public void whenSerializeAndDeserializeUsingJsonio_thenCorrect(){
    Foo foo = new Foo(1,"first");

    String jsonStr = JsonWriter.objectToJson(foo);
    Foo result = (Foo) JsonReader.jsonToJava(jsonStr);
    assertEquals(foo.getId(),result.getId());
}

Note that:

  • JsonWriter.objectToJson() is used to serialize Object to JSON.
  • JsonReader.jsonToJava() is used to deserialize Json to Java Object.
  • Sample JSON output:
{
    "@type":"org.baeldung.Foo",
    "id":1,
    "name":"first"
}

6. Genson

Genson is a Java and Scala to JSON conversion library, providing full databinding and streaming.

6.1. Useful Resources

Here are some official resources for the library:

6.2. Maven Dependency

<dependency>
    <groupId>com.owlike</groupId>
    <artifactId>genson</artifactId>
    <version>${genson.version}</version>
</dependency>

Note that the latest version of Genson right now is 1.3.

6.3. Simple Example with Genson

Here’s a simple example of working with the library:

@Test
public void whenSerializeAndDeserializeUsingGenson_thenCorrect(){
    Genson genson = new Genson();
    Foo foo = new Foo(1,"first");

    String jsonStr = genson.serialize(foo);
    Foo result = genson.deserialize(jsonStr, Foo.class);
    assertEquals(foo.getId(),result.getId());
}

Note that:

  • Genson.serialize() is used to serialize Object to JSON
  • Genson.desrialize() is used to deserialize JSON to Java Object

7. Conclusion

In this quick overview article, we learned about the most common JSON processing libraries in Java.

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