How to deserialize a JSON to Java object using the flexjson in Java?

Deserializing a JSON to a Java object means converting a JSON string into a Java object.

The deserialize() Method of the Flexjson Library

We will be using the Flexjson library to deserialize a JSON to a Java object in Java. The Flexjson library is a lightweight library that is used for serializing as well as deserializing Java objects to and from JSON.

A JSONDeserializer is the main class for performing deserialization of JSON to Java objects. We can deserialize a JSON string to a Java object using the deserialize(String json, Class<T> type) method of JSONDeserializer.

Syntax of deserialize() Method

The syntax of the deserialize() method is as follows:

public T deserialize(String json, Class<T> type)

To use the Flexjson library, we need to add it to our project. If you are using Maven, add this to your pom.xml file:

<dependency>
   <groupId>org.flexjson</groupId>
   <artifactId>flexjson</artifactId>
   <version>3.3</version>
</dependency>

If you do not use Maven, you can download the jar file from here.

Steps to Deserialize a JSON to Java Object

Following are the steps to deserialize a JSON to a Java object using the Flexjson library:

• Create a Java class that matches the structure of your JSON data (with appropriate fields and getters/setters).
• Create a JSONDeserializer instance and use the deserialize() method, specifying the target class.
• Pass the JSON string to the deserialize() method to convert it into a Java object.
• Use the resulting Java object as needed in your application.
• Handle any exceptions such as parsing errors using try-catch if necessary.

Example

Following is the code to deserialize a JSON to a Java object using the Flexjson library:

import org.flexjson.*;

public class DeserializeJsonExample {
   public static void main(String[] args) {
      // JSON string to be deserialized
      String jsonString = "{"name":"Ansh","age":23}";
      
      // Create a JSONDeserializer object
      JSONDeserializer<Person> deserializer = new JSONDeserializer<Person>();
      
      // Deserialize the JSON string to a Person object
      Person person = deserializer.deserialize(jsonString, Person.class);
      
      // Print the deserialized Person object
      System.out.println("Name: " + person.getName());
      System.out.println("Age: " + person.getAge());
   }
}
class Person {
   private String name;
   private int age;

   public Person(String name, int age) {
      this.name = name;
      this.age = age;
   }

   public String getName() {
      return name;
   }

   public int getAge() {
      return age;
   }
}

Output

Name: Ansh
Age: 23