Java map to json maps

How to Convert Java Map to JSON

In this post, we will learn how to convert Java Map into a JSON using 3 different libraries . As stated, we are going to use Gson , Jackson, and org.json libraries to achieve our objective one at a time. All three are quite famous libraries and used quite often.

In this tutorial, we are going to cover the below topics:

1. Map to JSON using Gson
2. Map to JSON using Jackson
3. Map to JSON using org.json

1. Convert Java Map to JSON using Gson

In order to work with Gson, we first need to add it’s dependency into the Project.

Maven dependencies

If you are using Maven as a build tool in your project, then add the following dependency in your pom.xml file.

else, access the below link and download & add the jar into your project classpath:

2. Convert Java Map to JSON using Jackson

In order to work with Jackson, we first need to add it’s dependency into the Project.

Maven dependencies

If you are using Maven as a build tool in your project, then add the following dependency in your pom.xml file.

else, download & add the following Jars into your project classpath:

In order to download jars, access below link and search for above-mentioned jar names and download the appropriate one from the search result.

3. Convert Java Map to JSON using org.json

In order to work with org.json, we first need to add it’s dependency into the Project.

Maven dependencies

If you are using Maven as a build tool in your project, then add the following dependency in your pom.xml file.

else, access the below link, it will download the jar in a zip file, extract it and & add this jar into your project classpath:

Do you like this Post? – then check my other helpful posts:

Other Useful References:

Author

Deepak Verma is a Test Automation Consultant and Software development Engineer for more than 10 years. His mission is to help you become an In-demand full stack automation tester. He is also the founder of Techndeck, a blog and online coaching platform dedicated to helping you succeed with all the automation basics to advanced testing automation tricks. View all posts

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2 Comments

In section 2. Convert Java Map to JSON using Jackson, you are still using GSON code snippet instead of Jackson, wrong copy-paste? Reply

Hi Serguei, Sorry for the inconvenience and thanks for pointing that out. Yes, that was the copy-paste issue. Well, I’ve fixed it now. Please take a look. Thanks Reply

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About Techndeck

Techndeck.com is a blog revolves around software development & testing technologies. All published posts are simple to understand and provided with relevant & easy to implement examples.

Techndeck.com’s author is Deepak Verma aka DV who is an Automation Architect by profession, lives in Ontario (Canada) with his beautiful wife (Isha) and adorable dog (Fifi). He is crazy about technologies, fitness and traveling etc. He runs a Travel Youtube Channel as well. He created & maintains Techndeck.com

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Convert Hashmap to JSON Object in Java

As always, the writeup is super practical and based on a simple application that can work with documents with a mix of encrypted and unencrypted fields.

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1. Introduction

In Java, a HashMap is a widely used data structure that we can use to store data in key-value pairs. On the other hand, JavaScript Object Notation (JSON) is a popular data interchange format commonly used to transmit data between a server and a web application.

In modern software development, it is common to encounter scenarios where data needs to be converted between different formats. One such scenario is converting a Map to JSON format.

In this tutorial, we’ll explore three ways to convert a Map to JSON format.

2. A Map Example and the Expected JSON Output

Let’s consider the following map example:

Map data = new HashMap<>(); data.put("CS", "Post1"); data.put("Linux", "Post1"); data.put("Kotlin", "Post1"); 

The expected JSON output should be as follows:

3. Java Map to JSON using Jackson

Jackson is one of the most popular Java libraries we can use while working with JSON. It offers powerful features for JSON parsing, generation, and data binding.

To convert a Map to JSON using Jackson, let’s include the jackson-databind dependency in our pom.xml file:

 com.fasterxml.jackson.core jackson-databind 2.15.1 

After including the dependency, we can define a test function to convert a Map to JSON using Jackson. Here’s an example:

String originalJsonData = ""; @Test public void given_HashMapData_whenUsingJackson_thenConvertToJson() throws JsonProcessingException < Mapdata = new HashMap(); data.put("CS", "Post1"); data.put("Linux", "Post1"); data.put("Kotlin", "Post1"); ObjectMapper objectMapper = new ObjectMapper(); String jacksonData = objectMapper.writeValueAsString(data); Assertions.assertEquals(jacksonData, originalJsonData); >

In the above code snippet, we created a HashMap object and added key-value pairs. Moreover, we used Jackson’s ObjectMapper to convert the HashMap to a JSON string and included assertions to verify the success of the conversion.

4. Java Map to JSON using Gson

Gson is another popular Java library that we can use to convert a Map to JSON and vice versa. It provides a simple and intuitive API for JSON processing.

Firstly we should include the following gson dependency in your pom.xml file:

 com.google.code.gson gson 2.10.1 

Once we have included the Gson dependency, we can define a test function that converts a Map to JSON using Jackson:

@Test public void given_HashMapData_whenUsingGson_thenConvertToJson() < Mapdata = new HashMap<>(); data.put("CS", "Post1"); data.put("Linux", "Post1"); data.put("Kotlin", "Post1"); Gson gson = new Gson(); Type typeObject = new TypeToken() <>.getType(); String gsonData = gson.toJson(data, typeObject); Assertions.assertEquals(gsonData, originalJsonData); >

The above code snippet represents a JUnit test method that uses the Gson library to convert a HashMap filled with key-value pairs into a JSON string and includes assertions to validate the successful conversion.

5. Java Map to JSON using JSON-Java

If we prefer a lightweight and minimalistic JSON library, we can use json since it provides a simple API for JSON manipulation.

To convert a Map to JSON using it, we need to add the org.json dependency to the pom.xml:

After including the json dependency in our project, we can now define a test function that converts a Map to JSON:

@Test public void given_HashMapData_whenOrgJson_thenConvertToJsonUsing() < Mapdata = new HashMap<>(); data.put("CS", "Post1"); data.put("Linux", "Post1"); data.put("Kotlin", "Post1"); JSONObject jsonObject = new JSONObject(data); String orgJsonData = jsonObject.toString(); Assertions.assertEquals(orgJsonData, originalJsonData); >

We created a HashMap object and populated it with key-value pairs. Then we used the JSON-Java library’s JSONObject class to convert the HashMap into a JSON object.

6. Conclusion

In this article, we discussed converting a Map to JSON in Java. It allows us to represent structured data in a widely accepted format for interoperability and exchange.

As always, the code is available over on GitHub.

Slow MySQL query performance is all too common. Of course it is. A good way to go is, naturally, a dedicated profiler that actually understands the ins and outs of MySQL.

The Jet Profiler was built for MySQL only, so it can do things like real-time query performance, focus on most used tables or most frequent queries, quickly identify performance issues and basically help you optimize your queries.

Critically, it has very minimal impact on your server’s performance, with most of the profiling work done separately — so it needs no server changes, agents or separate services.

Basically, you install the desktop application, connect to your MySQL server, hit the record button, and you’ll have results within minutes:

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