Read JSON in Java from URL that starts with unnecessary data

Question

I would like to process JSON data started with an object that I don't need.

Here you have the URL:

http://datos.santander.es/api/rest/datasets/callejero_calles.json?items=819

I have been trying to adapt next code, but I don't know how to avoid the first object (summary) and take the second one (resources).

If I want to take one by one all the data inside from each object of "resources" (for example, showing "nombre-calle", "tipo-via"...).

package leerjson;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;

public class LeerJSON {

    public static void main(String[] args) throws ParseException {
        JSONParser parser = new JSONParser();

        try {        
            URL oracle = new URL("http://datos.santander.es/api/rest/datasets/callejero_calles.json?items=819"); // URL to Parse
            URLConnection yc = oracle.openConnection();
            BufferedReader in = new BufferedReader(new InputStreamReader(yc.getInputStream()));

            String inputLine; 
            in.readLine();
            while ((inputLine = in.readLine()) != null) {   
                JSONArray a = (JSONArray) parser.parse(inputLine);

                // Loop through each item
                for (Object o : a) {
                    JSONObject datos = (JSONObject) o;
                    System.out.println(datos);
                }
            }
            in.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ParseException e) {
            e.printStackTrace();
        }  
    }

UPDATED: Once seen Enra64's answer, I don't know how to use getJSONArray and getJSONObject because it is not a method. I have included json-simple-1.1.1.jar to my project, but it doesn't work. Thank you in advance! This is my new code:

URL oracle = new URL("http://datos.santander.es/api/rest/datasets/callejero_calles.json?items=819"); // URL to Parse
   URLConnection yc = oracle.openConnection();
   BufferedReader in = new BufferedReader(new InputStreamReader(yc.getInputStream()));

   String inputLine = in.readLine();

   JSONObject a = (JSONObject) parser.parse(inputLine);
   JSONArray resources = a.getJSONArray("resources");

   for (int i = 0; i < resources.length(); i++) {
        resources.getJSONObject(i);
   }

this is a duplicate of https://stackoverflow.com/questions/4308554/simplest-way-to-read-json-from-a-url-in-java. In short you should be mapping the response to a Java object: see StaxMan answer on the above URL.There is no need to do this looping and JSONArray stuff since library like Jackson can parse the api response to Java object using a URL class param via ObjectMapper().readValue(URL,TheMapped.class); — Asura, Jan 14 '18 at 20:14

score 2 · Answer 1 · answered Jan 14 '18 at 19:34

2

Select the resources object as follows:

JSONObject a = (JSONObject) parser.parse(inputLine);
JSONArray resources = a.getJSONArray("resources");

And then loop through it:

for (int i = 0; i < resources.length(); i++) {
  resources.getJSONObject(i);
}

answered Jan 14 '18 at 19:34

enra64

96
1
3

Yes, what you are trying to do should be possible in every JSON library. Please accept my answer if it helped you :) – enra64 Jan 14 '18 at 19:53
Hi again, Enra64. I have left an answer about your code :) – windarin Jan 14 '18 at 20:02

Read JSON in Java from URL that starts with unnecessary data

1 Answers1