Serialize a Map Using the Flexjson Library in Java

Serializing a Map in Java is the process of converting a Map object into a format that can be easily stored or transmitted, such as JSON or XML.

We will use the Flexjson library to serialize a map in Java. We can serialize a Map using the serialize() method of the JSONSerializer class, which performs a shallow serialization of the target instance.

Example of Serializing a Map

We will take a map and see the output after serialization.

Map<String, String> map = new HashMap<>();
map.put("name", "Ansh");
map.put("age", "23");
map.put("city", "Mumbai");
map.put("country", "India");

After serialization, the map will look like this:

{"name":"Ansh","age":"23","city":"Mumbai","country":"India"}

Steps to Serialize a Map using Flexjson in Java

The following are the steps to serialize a map using Flexjson in Java:

• Add the Flexjson library to your project's dependencies.

• To add the Flexjson library to your project, you can use Maven. Add the following dependency to your pom.xml file:

  <dependency>
     <groupId>net.sf.flexjson</groupId>
     <artifactId>flexjson</artifactId>
     <version>3.3</version>
  </dependency>
  

• If you are not using Maven, you can download the jar file from here.
• Define your data class (e.g., Person) with fields and getters.
• In your main code, create a Map object.
• Instantiate a JSONSerializer: JSONSerializer serializer = new JSONSerializer();
• Call serializer.serialize(yourMap) to get the JSON string.
• Print or save the resulting JSON.

Example

In the below example, we will create a map of string key-value pairs and serialize it using Flexjson.

Following is the code to serialize a map using Flexjson in Java:

import net.sf.flexjson.JSONSerializer;
import java.util.HashMap;
import java.util.Map;
import java.util.Iterator;

public class FlexjsonExample {
   public static void main(String[] args) {
      // Create a map of string key-value pairs
      Map<String, String> map = new HashMap<>();
      map.put("name", "Ansh");
      map.put("age", "23");
      map.put("city", "Mumbai");
      map.put("country", "India");

      // Create a JSONSerializer object
      JSONSerializer serializer = new JSONSerializer();

      // Serialize the map to JSON
      String json = serializer.serialize(map);

      System.out.println(json);
   }
}

Output

Following is the output of the above code:

{"name":"Ansh","age":"23","city":"Mumbai","country":"India"}