How to Parse JSONObject and JSONArrays in Java? Beginner’s Guide

Here is a simple Java tutorial which demonstrate how to parse JSONObject and JSONArrays in Java.

JSON syntax is a subset of the JavaScript object notation syntax:

• Data is in name/value pairs
• Data is separated by commas
• Curly braces hold objects
• Square brackets hold arrays

Just incase if you want to take a look at simple JSON tutorial which I’ve written sometime back. In this example we will read JSON File Crunchify_JSON.txt from file system and then we will iterate through it.

In order to run below Java project, please add below Maven Dependency to your project in pom.xml file.

<dependency>
        <groupId>org.json</groupId>
        <artifactId>json</artifactId>
        <version>20151123</version>
</dependency>

---

Example-1.

Create this .txt file and update path in Java project:

{
    "blogURL": "https://crunchify.com",
    "twitter": "https://twitter.com/Crunchify",
    "social": {
        "facebook": "http://facebook.com/Crunchify",
        "pinterest": "https://www.pinterest.com/Crunchify/crunchify-articles",
        "rss": "https://crunchify.com/feed/"
    }
}

Java Program:

package com.crunchify.tutorials;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

import org.json.JSONException;
import org.json.JSONObject;

/**
 * @author Crunchify.com
 * 
 */

public class CrunchifyParseJSONObject {
        public static void main(String[] args) throws FileNotFoundException, JSONException {
                String jsonData = "";
                BufferedReader br = null;
                try {
                        String line;
                        br = new BufferedReader(new FileReader("/Users/<username>/Documents/Crunchify_JSON.txt"));
                        while ((line = br.readLine()) != null) {
                                jsonData += line + "\n";
                        }
                } catch (IOException e) {
                        e.printStackTrace();
                } finally {
                        try {
                                if (br != null)
                                        br.close();
                        } catch (IOException ex) {
                                ex.printStackTrace();
                        }
                }
                // System.out.println("File Content: \n" + jsonData);
                JSONObject obj = new JSONObject(jsonData);
                System.out.println("blogURL: " + obj.getString("blogURL"));
                System.out.println("twitter: " + obj.getString("twitter"));
                System.out.println("social: " + obj.getJSONObject("social"));
        }
}

Result:

blogURL: https://crunchify.com
twitter: https://twitter.com/Crunchify
social: {"facebook":"http://facebook.com/Crunchify","rss":"https://crunchify.com/feed/","pinterest":"https://www.pinterest.com/Crunchify/crunchify-articles"}

---

Example-2.

Here is a complete Java program that demonstrates parsing both JSON objects and arrays.

CrunchifyParseJsonObjectAndArray.java

package crunchify.com.java.tutorials;

import org.json.JSONArray;
import org.json.JSONObject;

/**
 * @author Crunchify.com
 * Program: How to Parse JSONObject and JSONArrays in Java? Beginner's Guide
 * 
 */

public class CrunchifyParseJsonObjectAndArray {
    public static void main(String[] args) {
        // JSON object string
        String jsonObjectString = "{\"name\":\"Crunchify\",\"year\":2023,\"city\":\"New York\"}";

        // Parse the JSON object string into a JSONObject
        JSONObject jsonObject = new JSONObject(jsonObjectString);

        // Extract values from the JSON object
        String name = jsonObject.getString("name");
        int year = jsonObject.getInt("year");
        String city = jsonObject.getString("city");

        // Print the values
        System.out.println("Name: " + name);
        System.out.println("Year: " + year);
        System.out.println("City: " + city);

        System.out.println();

        // JSON array string
        String jsonArrayString = "[{\"name\":\"Crunchify\",\"year\":2022,\"city\":\"London\"},{\"name\":\"Google\",\"year\":2022,\"city\":\"Paris\"}]";

        // Parse the JSON array string into a JSONArray
        JSONArray jsonArray = new JSONArray(jsonArrayString);

        // Loop through the JSONArray to extract values from each JSON object
        for (int i = 0; i < jsonArray.length(); i++) {
            JSONObject object = jsonArray.getJSONObject(i);
            name = object.getString("name");
            year = object.getInt("year");
            city = object.getString("city");

            System.out.println("Name: " + name);
            System.out.println("Year: " + year);
            System.out.println("City: " + city);
        }
    }
}

IntelliJ IDEA Result

Just run above program as a Java Application and you should see result as below.

Name: Crunchify
Year: 2023
City: New York

Name: Crunchify
Year: 2022
City: London
Name: Google
Year: 2022
City: Paris

Process finished with exit code 0

Details:

• The first step is to import the org.json.JSONObject and org.json.JSONArray classes, which are part of the org.json library.
• Then, we define a jsonObjectString variable, which holds a string representation of a JSON object.
• Using the JSONObject class, we parse the jsonObjectString into a JSONObject using the new JSONObject(jsonObjectString) constructor.
• Then, we use the getString, getInt, and getBoolean methods to extract values from the jsonObject.
• After printing out the values, we do a similar process to parse a jsonArrayString into a JSONArray and loop through each JSON object to extract and print values.

The post How to Parse JSONObject and JSONArrays in Java? Beginner’s Guide appeared first on Crunchify.