Rest API university student Max per city for hacker rank

App.java

/*
 * University Data App
 * Description: This Java program retrieves university data from a REST API, performs analysis, and prints results.
 * Author: Your Name
 */

package org.doogle;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.json.simple.*;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;

/**
 * Main class for the University Data App.
 */
public class App {

    /**
     * Main method of the application.
     * 
     * @param args Command-line arguments.
     * @throws IOException    If an I/O error occurs.
     * @throws ParseException If there is an error parsing JSON.
     */
    public static void main(String[] args) throws IOException, ParseException {
        // REST API URL for university data
        String urlString = "https://jsonmock.hackerrank.com/api/universities";
        // Get university data from the API
        JSONObject json = getUniversityData(urlString);

        // Calculate the number of pages based on total and per_page values
        Long total = (Long) json.get("total");
        Long perPage = (Long) json.get("per_page");
        Long numPage = total % perPage == 0 ? total / perPage : (total / perPage) + 1L;

        // Fetch data from additional pages and append to the JSONArray
        Long page = (Long) json.get("page");
        JSONArray jsonArray = (JSONArray) json.get("data");
        for (Long p = page + 1L; p <= numPage; p++) {
            JSONObject universityJson = getUniversityData(urlString + "?page=" + String.valueOf(p));
            jsonArray.addAll((JSONArray) universityJson.get("data"));
        }

        // Analysis variables
        String city1 = "Singapore sdf"; // Replace with the desired city
        String city2 = ""; // Replace with the desired city
        String firstUniversity = "NOT_COMPUTED";
        String secondUniversity = "NOT_COMPUTED";
        Long maxFirstUniversity = 0L;
        Long maxSecondUniversity = 0L;
        Map<String, List<String>> cities = new HashMap<String, List<String>>();

        // Perform analysis on university data
        for (int i = 0; i < jsonArray.size(); i++) {
            JSONObject o = (JSONObject) jsonArray.get(i);
            String city = (String) ((JSONObject) o.get("location")).get("city");
            String university = (String) o.get("university");
            Long intStudents = Long.valueOf(((String) o.get("international_students")).replace(",", ""));
            List<String> univList = cities.getOrDefault(city, new ArrayList<>());
            univList.add(university + ":" + (String) o.get("international_students"));
            cities.put(city, univList);
            if (city1.equals(city) && intStudents > maxFirstUniversity) {
                maxFirstUniversity = intStudents;
                firstUniversity = university;
            } else if (city2.equals(city) && intStudents > maxSecondUniversity) {
                maxSecondUniversity = intStudents;
                secondUniversity = university;
            }
        }

        // Print the result
        System.out.println("NOT_COMPUTED".equals(firstUniversity) ? secondUniversity : firstUniversity);
    }

    /**
     * Retrieves university data from a given URL.
     * 
     * @param urlString URL of the REST API.
     * @return JSONObject containing the university data.
     * @throws MalformedURLException If the URL is malformed.
     * @throws IOException           If an I/O error occurs.
     * @throws ProtocolException     If there is an issue with the HTTP protocol.
     * @throws ParseException        If there is an error parsing JSON.
     */
    private static JSONObject getUniversityData(String urlString)
            throws MalformedURLException, IOException, ProtocolException, ParseException {
        URL url = new URL(urlString);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setRequestMethod("GET");
        int res = conn.getResponseCode();
        BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String line;
        StringBuilder sb = new StringBuilder();
        while ((line = reader.readLine()) != null) {
            sb.append(line);
        }
        reader.close();
        JSONParser parser = new JSONParser();
        JSONObject json = (JSONObject) parser.parse(sb.toString());
        return json;
    }
}