How do i get particular field from the Json in Java?

Question

Suppose, I have a Json & I want to get the value of particular field from the Json then How can i achieve that?

Please open below link to have a look at the json.

Json: https://jsoneditoronline.org/?id=05f3f2de21184ea19a105b4e5219c675

Now, I want to get values of all 'created' which we can find inside object->changelog->histories->0->created/1->created/2->created....30->created.

We can also refer left hand side json if required.

How can i get the value of created in java code? Please help me here.

Answer 1

You can use org.json, and with a JSONObject you can get what you want

JSONObject json = new JSONObject(yourjsonString);

---Add after comment ---

I propose you :

JSONObject json = new JSONObject(yourjsonString);//it's object
JSONObject changelog = json.getJSONObject("changelog");
JSONArray histories = changelog.getJSONArray("histories");
histories.getJSONObject(0); //first json in histories

You can concat if you want.
Try by yourself to get exactly what you want.

Answer 2

Make a call on your url to retrieve your json content.

String jsonString = requestInfoFromUrl(urlLink);   

private String requestInfoFromUrl(String url) throws IOException {
      UriComponentsBuilder builder = UriComponentsBuilder.fromUriString(url);
      HttpGet getMethod = new HttpGet(builder.build().toUri());
      HttpResponse response = httpClient.execute(getMethod);

      if (response.getStatusLine().getStatusCode() == 200){
             return EntityUtils.toString(response.getEntity());
      } else {
             LOG.error("Error appear while request response from an url.");
             return null;
      }
}

Now , in jsonString we have all the json from url. Now let's retrieve a field(changelog field) from that json:

String changelog = extractFromJsonAStringWithKey(jsonString, "changelog");

 private String extractFromJsonAStringWithKey(String jsonString, String key){
        JSONObject jsonObject = new JSONObject(jsonString);
        return (String) jsonObject.get(key);
}

Answer 3

The best way to do it is to use some library dedicated for it like:

• Jackson
• Gson
• JsonPath