Java Gson fromJson() Example

Gson is a Java serialization/deserialization library to convert Java Objects into JSON and back. Gson was created by Google for internal use and later open sourced.

The Gson.fromJson() method deserializes the specified JSON into an object of the specified class.

Java Gson Maven dependency

This is a Maven dependency for Gson:

<dependency>
    <groupId>com.google.code.gson</groupId>
    <artifactId>gson</artifactId>
    <version>2.8.2</version>
</dependency>

Java Gson fromJson() Example

The example uses fromJson() method to read JSON into a Java object.

import com.google.gson.Gson;

class User {

    private final String firstName;
    private final String lastName;

    public User(String firstName, String lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }
        
    @Override
    public String toString() {
        return new StringBuilder().append("User{").append("First name: ")
                .append(firstName).append(", Last name: ")
                .append(lastName).append("}").toString();
    }
}

public class GsonFromJson {

    public static void main(String[] args) {

        String json_string = "{\"firstName\":\"Tom\", \"lastName\": \"Broody\"}";

        Gson gson = new Gson();
        User user = gson.fromJson(json_string, User.class);

        System.out.println(user);
    }
}

Output:

User{First name: Tom, Last name: Broody}