Java- How to store Parsing nested json data into Java list

Question

I Tring to monitor my site performance day by day activity with help of google api

and i tried to fetch items in network request from googleapi of pagespeedonline

but its not working on my code

REST API link :

https://www.googleapis.com/pagespeedonline/v5/runPagespeed?url=https://lifemachi.blogspot.com&key=AIzaSyBfHVlhNEnf26Ea8-ZOhiYOe0HrQZtLvRI&category=performance&strategy=desktop

and i try to get particularly

lighthouseResult -> audits -> network-requests ->details-> items

and store each items into record...

i tried below codes

package FirstTestNgPackage;



import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.*;
import org.json.*;

public class testingJSON {
       static String inline = "";
   public static void main(String args[]) throws JSONException, InterruptedException, IOException {
       // url
       URL url = new URL("https://www.googleapis.com/pagespeedonline/v5/runPagespeed?url=https://lifemachi.blogspot.com&key=AIzaSyBfHVlhNEnf26Ea8-ZOhiYOe0HrQZtLvRI&category=performance&strategy=desktop");
      // read it from URL
       Scanner sc = new Scanner(url.openStream()); Thread.sleep(300);
       String jsonDataString = sc.nextLine();
       while(sc.hasNext())
        {
            inline+=sc.nextLine();
        }
       sc.close();
        
      List<String> list = new ArrayList<String>();
      
   
// just print that inline var
        
        System.out.println(inline);
        System.out.println("--------1");
    
      }
   }

and i got proper output... but how to store items values in list ?

Thanks in advance

Answer 1

First you must parse the output arrray named "inline" to valid JSON string . Here you can use the functionalities of org.json library,

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.*;
import org.json.*;

    public class testingJSON {

        static String inline = "";

        public static void main(String args[]) throws JSONException, InterruptedException, IOException {
     
         // url
         URL url = new URL("https://www.googleapis.com/pagespeedonline/v5/runPagespeed?url=https://lifemachi.blogspot.com&key=AIzaSyBfHVlhNEnf26Ea8-ZOhiYOe0HrQZtLvRI&category=performance&strategy=desktop");
    
        // read it from URL

        Scanner sc = new Scanner(url.openStream()); Thread.sleep(300);
        String jsonDataString = sc.nextLine();

            while(sc.hasNext()){
                inline+=sc.nextLine();
            }

            sc.close();

            // just print that inline var
            System.out.println(inline);
            System.out.println("--------1");

            //Tokenize the string data json array
            JSONArray data = new JSONArray(new JSONObject(new JSONTokener(inline)));

            //or JSONArray data = new JSONArray(new JSONObject(inline));

            //The array list we want to insert the formatted JSON string
            ArrayList<String> list = new ArrayList<String>();
    
            if(data !=null){
                for(int i=0;i<data.length();i++){
                    list.add(data.getString(i));
                }
            }

            System.out.println(list);
        }
    }

Here I have got following error

Exception in thread "main" org.json.JSONException: A JSONObject text must begin with '{' at 3 [character 4 line 1]
    at org.json.JSONTokener.syntaxError(JSONTokener.java:432)
    at org.json.JSONObject.<init>(JSONObject.java:184)
    at testingJson.main(testingJson.java:31)

From this we can identify that something missed-format with inline variable while tokenize that to JSON string

In JSON string the format must be like this [ { the JSON data } ] .

Answer 2

If you only want to retrieve the JSON array items in whole JSON response, it can be easily done by using JsonPath as follows:

Code snippet

List<String> items = JsonPath.parse(inline).read("$.lighthouseResult.audits.network-requests.details.items");

Maven dependency

<!-- https://mvnrepository.com/artifact/com.jayway.jsonpath/json-path -->
<dependency>
    <groupId>com.jayway.jsonpath</groupId>
    <artifactId>json-path</artifactId>
    <version>2.4.0</version>
</dependency>

Answer 3

Assuming you have the complete json response in inline variable, you can convert it to JSONObject and then keep on reading the child attributes.

JSONObject jsonObject = new JSONObject(inline);
JSONObject lighthouseResult = jsonObject.getJSONObject("lighthouseResult");
JSONObject audits = lighthouseResult.getJSONObject("audits");
JSONObject networkRequests = audits.getJSONObject("network-requests");
JSONObject details = networkRequests.getJSONObject("details");

//Notice that here we are reading an array
JSONArray items = details.getJSONArray("items");

// Create String list and add elements to it from items JSONArray object
List<String> itemsList = new ArrayList<>();
items.forEach(item -> itemsList.add(item.toString()));