How to Parse JSON in Java

Java is one of the most widely used programming languages in the world, and it has excellent support for working with JSON data.

JSON (JavaScript Object Notation) is a lightweight data-interchange format that is easy for humans to read and write and easy for machines to parse and generate.

In this tutorial, we will take a deep dive into the topic of parsing JSON in Java.


What is JSON?

JSON is a data format that is used to exchange information between a server and a client.

It is a language-independent data format and can be easily parsed by most programming languages, including Java.

The format is based on the key-value pairs, where the key is a string, and the value can be either a string, a number, an array, or another JSON object.

JSON is widely used in RESTful web services, where the server returns data in JSON format.

Why Use JSON in Java?

Java has a wide range of libraries and tools that make it easy to work with JSON data.

This makes it a popular choice for developers who want to build applications that consume or produce JSON data.

Additionally, JSON is easy to read and write, which makes it easy to understand and debug.

Parsing JSON in Java:

In Java, you can parse JSON using either a library or a built-in API.

In this section, we will take a look at some of the most popular libraries and APIs for parsing JSON in Java.

Jackson Library

The Jackson library is one of the most popular libraries for parsing JSON in Java.

It is fast, easy to use, and has a lot of features that make it a popular choice for developers.

To use the Jackson library, you will need to include the Jackson libraries in your project.

The following code example shows how to parse a JSON string using the Jackson library:

import com.fasterxml.jackson.databind.ObjectMapper;

String json = "{\"name\":\"John\",\"age\":30,\"city\":\"New York\"}";

ObjectMapper mapper = new ObjectMapper();

User user = mapper.readValue(json, User.class);

System.out.println(user);

Gson Library

The Gson library is another popular library for parsing JSON in Java.

It is easy to use, and it has a lot of features that make it a popular choice for developers.

To use the Gson library, you will need to include the Gson libraries in your project.

The following code example shows how to parse a JSON string using the Gson library:

import com.google.gson.Gson;

String json = "{\"name\":\"John\",\"age\":30,\"city\":\"New York\"}";

Gson gson = new Gson();

User user = gson.fromJson(json, User.class);

System.out.println(user);

Java API

Java also has a built-in API for parsing JSON. The API is called the JSON API and is included in the Java SE (Standard Edition) library.

The JSON API is a low-level API that requires a lot of code to parse JSON data.

However, it is a good option if you want to parse JSON data without using a third-party library.

The following code example shows how to parse a JSON string using the Java API:

import

java.io.StringReader;
import javax.json.Json;
import javax.json.JsonObject;
import javax.json.JsonReader;

String json = "{"name":"John","age":30,"city":"New York"}";

StringReader reader = new StringReader(json);

JsonReader jsonReader = Json.createReader(reader);

JsonObject object = jsonReader.readObject();

String name = object.getString("name");
int age = object.getInt("age");
String city = object.getString("city");

System.out.println("Name: " + name);
System.out.println("Age: " + age);
System.out.println("City: " + city);

Conclusion

Parsing JSON in Java is straightforward and can be done using either a library or a built-in API.

In this article, we looked at some of the most popular libraries and APIs for parsing JSON in Java, including the Jackson library, the Gson library, and the Java API.

Regardless of the method you choose, parsing JSON in Java is easy and will allow you to quickly and efficiently work with JSON data in your Java applications.