Download the ZIP file from this URL and extract it to get the Jar. Add the Jar to your build path. To check the available classes in this Jar use this URL.

To Add this Jar to your build path Right click the Project > Build Path > Configure build path> Select Libraries tab > Click Add External Libraries > Select the Jar file Download

I hope this will solve your problem

• Right click on the Eclipse project,
• choose Properties
• Select Java Build Path
• Click the libraries tab
• click add external jars
• find the json jar(s) and add them.

import org.json.simple.JSONArray;

I got it to work with the following:

public static void main(String[] args) throws IOException, ParseException{
    FileReader reader = new FileReader(new File("filename.json"));


    JSONParser jsonParser = new JSONParser();
    JSONArray jsonArray = (JSONArray) jsonParser.parse(reader);
    JSONObject object = (JSONObject) jsonArray.get(0);
    long elementaryProductId = (Long) object.get("elementaryProductId");



    System.out.println("The id is: " + elementaryProductId);
}

Explanation of the above:

You know the outermost element is an array so parse straight into a JSONArray. Next you want to pull out the first element of that array which is a JSONObject (its in braces). After that the code should be fairly self explanatory :)

If using Maven, add this dependency to your pom.xml

<dependency>
    <groupId>javax.json</groupId>
    <artifactId>javax.json-api</artifactId>
    <version>1.0</version>
</dependency>

For Gradle, add this to your build.gradle

compile 'javax.json:javax.json-api:1.0'

You need to use the fully-qualified class name, which includes the package:

import org.json.JSONArray;

(And yes, that is the correct way to add classes/jars to your project's classpath in Eclipse.)

In Eclipse , navigate to

Windows ->Preferences -> Java -> Build Path -> ClassPath Variables

If your classpath variable 'JSON_JARS' is not present there, add it there, alongwith its location.

This should resolve your 'unbound classpath variable' error, if you have this error.

Moreover, put your execution codes in some method, or at least in main. For example :

package test;

import org.json.simple.*;

public class JSONTest {

    public void testMethod(){
        JSONObject obj = new JSONObject();
        obj.put("name","test");

        JSONArray list = new JSONArray();
        list.add("1234");
    }

    public static void main(String [] args){
        JSONObject obj = new JSONObject();
        obj.put("name","test");

        JSONArray list = new JSONArray();
        list.add("1234");
    }
}

This doesn't throw any error.

For the code which you have attached, if I am correct, there is no way for the code to populate the object and list, to get executed. This is why you get those errors.

The question is a bit unclear, so my answer is equally general...

In order to use a third-party library in Java (like JSON-lib in your case), the library must be present during compilation and during execution (runtime) of your program. This is done by downloading the .jar file and telling Java where to find it. Java uses the concept of classpath:

Classpath is a parameter – set either on the command-line, or through an environment variable – that tells the Java Virtual Machine or the compiler where to look for user-defined classes and packages.

(from Wikipedia)

The error you mention ("Import org.json.JSONObject cannot be resolved") means that the .jar wasn't on the classpath during compilation.

To add a third-party library in Eclipse, store the .jar file somewhere in your project (a dedicated lib folder would be a good choice), then right-click on your project, choose Properties → Java Build Path → Libraries, click "Add JARs..." and choose your .jar file. From now on, Eclipse will add it to the classpath during compilation.

Adding it to the classpath during execution depends on the kind of project you're running. If you have a simple main method which you're running from Eclipse, the .jar will be automatically added to the classpath. If you're running a web application in a container such as Tomcat, JBoss etc., then the standard way to add the .jar to the classpath would be to put it in the WEB-INF/lib directory of your deployed application. Have a look at the Java EE tutorial for more information on web applications and their deployment.