Answer to Question #284358 in Java | JSP | JSF for Elizabeth Nancy

Question

Find latitude and longitude of utmost 20 countries, ordered by population, with a population greater or equal to the population limit given below and have atleast one currency exclusively for themselves. (countries like Madagascar, Sri Lanka but not India, USA)Your task is to find the sum of the length of all lines (in kms) that can be drawn between co-ordinates of these countries.

• Assume radius of earth: 6371 km
• Round length of each line and final result to 2 decimal points
• If co-ordinates are missing for any country use 0.000 N 0.000 E

Answer 1

import java.util.ArrayList;

public class Main {
    public static void main(String[] args) {
        int r = 6371000;// metres
        ArrayList<Country> allCountries = new ArrayList<>();
        ArrayList<Country> countries = new ArrayList<>();
        for (Country country : allCountries) {
            if (country.getNumberOfCurencies() > 1) {
                countries.add(country);
                if (countries.size() == 20) {
                    break;
                }
            }
        }
        double total = 0;
        for (int i = 0; i < countries.size() - 1; i++) {
            for (int j = i + 1; j < countries.size(); j++) {
                double fi1 = countries.get(i).getLatitude() * Math.PI / 180; // φ, λ in radians
                double fi2 = countries.get(j).getLatitude() * Math.PI / 180;
                double dFi = (countries.get(j).getLatitude() - countries.get(i).getLatitude()) * Math.PI / 180;
                double dLam = (countries.get(j).getLongitude() - countries.get(i).getLongitude()) * Math.PI / 180;
                double a = Math.sin(dFi / 2) * Math.sin(dFi / 2) +
                        Math.cos(fi1) * Math.cos(fi2) * Math.sin(dLam / 2) * Math.sin(dLam / 2);
                double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
                total += r * c;
            }
        }
        System.out.printf("Total distance: %.2f\n", total / 1000);
    }
}