How to convert JSON string to Java object?

In the following example we will convert JSON string to Java object using ObjectMapper class from the Jackson library. This class provides a method readValue(String, Class<T>) which will deserialize a JSON string into Java object. The first argument to the method is the JSON string and the second parameter is the result type of the conversion.

In the code below you will see:

  • Define a JSON string, here we have the id and name keys.
  • Create a Jackson ObjectMapper which maps JSON string to POJO.
  • Map the json string into an Artist object by calling the readValue() method.
  • Read the value of artist object properties.
package org.kodejava.jackson;

import com.fasterxml.jackson.databind.ObjectMapper;
import org.kodejava.jackson.support.Artist;

import java.io.IOException;

public class JsonToObject {
    public static void main(String[] args) {
        String json = """
                {
                    "id": 1,
                    "name": "The Beatles"
                }
                """;

        ObjectMapper mapper = new ObjectMapper();
        try {
            Artist artist = mapper.readValue(json, Artist.class);
            System.out.println("Artist = " + artist);

            System.out.println("artist.getId() = " + artist.getId());
            System.out.println("artist.getName() = " + artist.getName());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

And here is the definition of Artist class.

package org.kodejava.jackson.support;

public class Artist {
    private Long id;
    private String name;

    public Artist() {
    }

    public Artist(Long id, String name) {
        this.id = id;
        this.name = name;
    }

    // Getters & Setters

    @Override
    public String toString() {
        return "Artist{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

The code snippet above will print to following output:

Artist = Artist{id=1, name='The Beatles'}
artist.getId() = 1
artist.getName() = The Beatles

Maven Dependencies

<dependencies>
    <!-- https://search.maven.org/remotecontent?filepath=com/fasterxml/jackson/core/jackson-core/2.13.3/jackson-core-2.13.3.jar -->
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-core</artifactId>
        <version>2.13.3</version>
    </dependency>
    <!-- https://search.maven.org/remotecontent?filepath=com/fasterxml/jackson/core/jackson-annotations/2.13.3/jackson-annotations-2.13.3.jar -->
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-annotations</artifactId>
        <version>2.13.3</version>
    </dependency>
    <!-- https://search.maven.org/remotecontent?filepath=com/fasterxml/jackson/core/jackson-databind/2.13.3/jackson-databind-2.13.3.jar -->
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.13.3</version>
    </dependency>
</dependencies>

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