Example how to fetch and parse JSON data in Java 11+

FetchAndParseJSON.java

package de.niftycode;

import org.json.JSONArray;
import org.json.JSONObject;

import java.net.URI;
import java.net.http.HttpClient; // < New in Java 11, can also handle HTTP/2 requests!
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

/*
Send HTTP requests using the new API
(Java 11 and above)
This example uses the new java.net.HttpClient which handles
asynchronous operations automatically.
 */
public class Main {

    public static void main(String[] args) {

        String url = "https://xern-statistic.de/api/countries";

        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create(url))
                .build();

        try {
            client.sendAsync(request, HttpResponse.BodyHandlers.ofString())
                    .thenApply(HttpResponse::body)
                    .thenApply(Main::parse)
                    .join();
        } catch(Exception e) {
            System.out.println("ERROR!");
            System.out.println(e);
        }
    }

    public static String parse(String responseBody) {
        JSONArray nations = new JSONArray(responseBody);

        try {
            for (int i = 0; i < nations.length(); i++) {
                JSONObject nation = nations.getJSONObject(i);
                String country = nation.getString("country");
                String capital = nation.getString("capital");
                String government = nation.getString("government");
                int population = nation.getInt("population");
                System.out.println("Country: " + country);
                System.out.println("Capital: " + capital);
                System.out.println("Government: " + government);
                System.out.println("Population: " + population);
                System.out.println("---");
            }
        } catch(Exception e){
            System.out.println(e);
        }
        return null;
    }
}