[Jackson API Examples] - How to Convert Java Set Object to/from JSON String using Jackson?(Serialize and De-serialize)

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 Hi Guys,

Welcome to Java Inspires.

In this post, we will see how to serialize and de-serialize java Set (HashSet)object using Jackson api.

Here, we are using ObjectMapper class from JAckson library and writeValueAsString method to convert serialize and readValue method to deserialize.

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How to Convert Java Set Object to/from JSON String using Jackson?(Serialize and Deserialize)

MainApp.java

package com.javainspires;

import java.io.IOException;
import java.util.HashSet;
import java.util.Set;

import com.fasterxml.jackson.databind.ObjectMapper;

/**
 * 
 * @author #JavaInspires
 *
 */
public class MainApp {

	public static void main(String[] args) throws IOException {

		// create a Set object
		Set<String> sampleSet = new HashSet<>();
		sampleSet.add("C");
		sampleSet.add("C++");
		sampleSet.add("Java");
		sampleSet.add("Python");
		sampleSet.add("GoLang");
		sampleSet.add("Kotlin");

		// create object mapper class object
		ObjectMapper mapper = new ObjectMapper();
		// convert set object to json string using this mapper
		String jsonStr = mapper.writeValueAsString(sampleSet);

		System.out.println("\nJava Set Object To JSON\n");
		// print json string
		System.out.println(jsonStr);

		// now convert this json string to java set object
		// using object mapper

		Set<String> set1 = mapper.readValue(jsonStr.getBytes(), Set.class);

		System.out.println("\nJSON String to Java Set Object\n");
		// print this list
		set1.forEach(System.out::println);

	}
}

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Output :

Java Set Object To JSON

["Java","C++","C","GoLang","Python","Kotlin"]

JSON String to Java Set Object

Java
C++
C
GoLang
Python
Kotlin

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.javainspires</groupId>
	<artifactId>jackson-examples</artifactId>
	<version>0.0.1-SNAPSHOT</version>

	<dependencies>

		<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
		<dependency>
			<groupId>com.fasterxml.jackson.core</groupId>
			<artifactId>jackson-databind</artifactId>
			<version>2.12.2</version>
		</dependency>

	</dependencies>
</project>

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