How to convert a json data to string in java

Question

I want to convert json data to string

import java.io.BufferedReader;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import org.json.JSONArray;
import org.json.JSONObject;
public static void main(String[] args) throws Exception
{

    URL url = new URL("http://192.168.1.13/test/ProductWb.php?productId=9");
    HttpURLConnection conn ;
    conn = (HttpURLConnection) url.openConnection();
    conn.setRequestMethod("GET");
    conn.setReadTimeout(60);
    conn.setRequestProperty("Accept", "application/json");
    String json="";

    json = readUrl(conn);
           System.out.println(json);
           JSONObject jsonObject=new JSONObject(json);
           JSONArray jarray=jsonObject.getJSONArray("modeles");
           JSONObject  modele= jarray.getJSONObject("modele");
           for (int i=0;i<modele.length();i++) {
               System.out.println(modele(i).getString("id_product"));
                System.out.println(modele(i).getString("meta_title"));
                System.out.println("*********");
              }


}

its show me the json data but give me this the error:

{"modeles":[{"modele":{"id_product":"9","id_shop":"1","id_lang":"4","description":null,"description_short":"<pre>Peugeot 208<\/pre>","info_prix":"","info_1":null,"info_2":null,"info_3":null,"info_4":null,"info_5":null,"link_rewrite":"208","meta_description":"Peugeot 208","meta_keywords":"peugeot 208","meta_title":"Peugeot 208","name":"208","available_now":"","available_later":""}}]}
Exception in thread "main" java.lang.IllegalStateException: This is not a JSON Array.
at com.google.gson.JsonElement.getAsJsonArray(JsonElement.java:106)
at com.autoreduc.services.TestProduct.main(TestProduct.java:59)

help me if you have any solution. thanks in advance

It's pretty clear that This is not a JSON Array. Also, where do you see a NullPointereException? — Sotirios Delimanolis
– Sotirios Delimanolis, Commented Apr 7, 2014 at 14:07
You should most definitely familiarize yourself with the json format. — Sotirios Delimanolis
– Sotirios Delimanolis, Commented Apr 7, 2014 at 14:08
He means that you state in your question that you've got a NullPointereException (sic), when there's no mention of that exception in your stack trace. It's an IllegalStateException — Rob Baillie
– Rob Baillie, Commented Apr 7, 2014 at 14:12

Mena · Accepted Answer · 2014-04-07 14:08:46Z

6

Your JSON is not an array.

It's a JSON object with one property: modeles, whose value is the array.

Parse the root as JsonObject.

answered Apr 7, 2014 at 14:08

Mena

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1 Comment

Rob Baillie Over a year ago

You got to love a library construct for interpreting a format that requires you to understand the format and know what you've got before you interpret it!

suthar_arun · Accepted Answer · 2021-02-24 04:43:31Z

5

You can use ObjectMapper to convert objects to json string:

ObjectMapper mapper = new ObjectMapper();
try {
  String json = mapper.writeValueAsString(cat);
  System.out.println("ResultingJSONstring = " + json);
  //System.out.println(json);
} catch (JsonProcessingException e) {
   e.printStackTrace();
}

answered Feb 24, 2021 at 4:43

suthar_arun

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1 Comment

webjockey Over a year ago

You need to add this as well mapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);

Nambi · Accepted Answer · 2014-04-07 14:41:17Z

1

{->represents JSONObject and [->represents the JSONArray, first get the jsonObject and then get the array in it.

I tried with jsonObject package import the jar

 JSONObject jsonObject=new JSONObject(yourstring);
    JSONArray jarray=jsonObject.getJSONArray("modeles");
 JSONObject  modele= jarray.getJSONObject("modele");
   for (int i=0;i<modele.length();i++) {
       System.out.println(modele(i).getString("id_product"));
        System.out.println(modele(i).getString("meta_title"));
        System.out.println("*********");
      }

edited Apr 7, 2014 at 14:41

answered Apr 7, 2014 at 14:11

Nambi

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8 Comments

ss3419670 Over a year ago

what is JSONObject because its not accepted by the eclipse?

user1907906 Over a year ago

@ss3419670 Please include the relevant imports in your question.

ss3419670 Over a year ago

i do it but it give me to add cast to jarray.get(i) ?

ss3419670 Over a year ago

yeah i look it , i found this error with your last answer

Nambi Over a year ago

@ss3419670 sorry,i didn't recognize your json please see my final edit

|

halloleo · Accepted Answer · 2019-02-15 01:31:13Z

In your code you read the json data from a URL. I just copied your data and pasted it in a file and read the file as your url was down. Here step by step I have shown how to parse your json object and content inside it. For this I used java-json-schema.jar.

    import java.io.FileNotFoundException;
    import java.io.FileReader;
    import java.io.IOException;
    import java.util.Iterator;
    import org.json.simple.JSONArray;
    import org.json.simple.JSONObject;
    import org.json.simple.parser.JSONParser;
    import org.json.simple.parser.ParseException;
    public class Tets {

        /**
         * @param args
         */
        public static void main(String[] args) {
            // TODO Auto-generated method stub
            JSONParser parser = new JSONParser();
           try{
          /*  URL url = new URL("http://192.168.1.13/test/ProductWb.php?productId=9");
            HttpURLConnection conn ;
            conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("GET");
            conn.setReadTimeout(60);
            conn.setRequestProperty("Accept", "application/json");*/
            String json="";

            Object obj = parser.parse(new FileReader("C:\\XXX\\XX\\src\\javapackage\\t.json"));

            JSONObject jsonObject = (JSONObject) obj;
            System.out.println(jsonObject.toJSONString());  //modeles object
            JSONArray name = (JSONArray) jsonObject.get("modeles");
            System.out.println(name.toJSONString());//array inside modeles array


            for (Object o : name)
              {
                JSONObject person = (JSONObject) o;
                 JSONObject person1 = (JSONObject)person.get("modele");
                              System.out.println(person.get("modele"));//modele object
                              System.out.println(person1.get("id_lang"));//modele attribute
              } 



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

        }
    }

OutPut

Your Json Object

{"modeles":[{"modele":{"id_lang":"4","info_5":null,"info_4":null,"link_rewrite":"208","meta_keywords":"peugeot 208","info_3":null,"info_2":null,"info_1":null,"available_now":"","meta_description":"Peugeot 208","id_product":"9","description_short":"<pre>Peugeot 208<\/pre>","description":null,"name":"208","info_prix":"","meta_title":"Peugeot 208","available_later":"","id_shop":"1"}}]}

Your Json Array contained in json Object

[{"modele":{"id_lang":"4","info_5":null,"info_4":null,"link_rewrite":"208","meta_keywords":"peugeot 208","info_3":null,"info_2":null,"info_1":null,"available_now":"","meta_description":"Peugeot 208","id_product":"9","description_short":"<pre>Peugeot 208<\/pre>","description":null,"name":"208","info_prix":"","meta_title":"Peugeot 208","available_later":"","id_shop":"1"}}]

Your Json Object inside array

{"id_lang":"4","info_5":null,"info_4":null,"link_rewrite":"208","meta_keywords":"peugeot 208","info_3":null,"info_2":null,"info_1":null,"available_now":"","meta_description":"Peugeot 208","id_product":"9","description_short":"<pre>Peugeot 208<\/pre>","description":null,"name":"208","info_prix":"","meta_title":"Peugeot 208","available_later":"","id_shop":"1"}

Your Json Object id_lang atrribute value = 4

enter image description here

i do your proposition but it give me this exception -->Can only iterate over an array or an instance of java.lang.Iterable ,in this --> code part: (Object o : name)
did you copy my whole code and and pasted it or did you write it from scratch based on my proposition

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