JSON (simple) parsing of file returns null values

Question

It's my first time working with a JSON file, so I went with simple JSON library. Here's what works:

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

import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;

public class ParseCardJSON {

    public static void main(String[] args) {

        JSONParser parser = new JSONParser();

        Object obj;

        try {
          obj = parser.parse(new FileReader("C:\\Users\\owner\\Desktop\\A\\programming\\workspace\\MTG\\AllSets.json"));
          JSONObject jsonObject = (JSONObject) obj;
          System.out.println(obj.toString());
          String name = (String) jsonObject.get("name");
          String color = (String) jsonObject.get("power");
          System.out.println("Name: " + name);
          System.out.println("color: " + color);

        } catch (Exception e) {
          e.printStackTrace();
        }
    }
}

So the System.out.println(obj.toString()); prints out what I'm expecting:

({"LEA":{"name":"Limited Edition Alpha","code":"LEA","gathererCode":"1E","magicCardsInfoCode":"al","releaseDate":"1993-08-05","..)...

but the "name" and "color" prinlns are null. Any idea what could be wrong?

Giuseppe Scopelliti · Accepted Answer · 2016-02-28 19:22:56Z

3

This happen because the name property is not in the root.

In fact you have a LEA key that is in the root, and the value of that property is another Object, that contains the following keys : name, code, gathererCode, magicCardsInfoCode, etc...

So if you want extract the name property, you need to do something like this

JSONObject object = (JSONObject) jsonObject.get("LEA");
String name = (String) object.get("name");

This should fix the problem.

answered Feb 28, 2016 at 19:22

Giuseppe Scopelliti

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4 Comments

Phant Over a year ago

Appreciate it. So if I'm understanding, the entire JSON object is wrapped in a key, so I need to let my parser know that so that it delves beyond just the top level? Unfortuntely, jsonObject.get is throwing an error for me though (Cannot make a static reference to the non-static method get(Object) from the type HashMap). Any idea how to fix this? Removing the static in a main isn't really an option, right?

Giuseppe Scopelliti Over a year ago

Could you provide the code please? I'll show you the fix.

Phant Over a year ago

Looks like it's working now, so it must have been something little I was doing. Thanks for the help!

Giuseppe Scopelliti Over a year ago

No problem. My pleasure

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