Mini Java Projects: Currency Converter

CurrencyConverter.java

// https=//hackr.io/blog/java-projects Currency Converter

import java.net.URL;
import java.util.*;
import java.util.stream.Collectors;

public class CurrencyConverter {

    public static void main(String[] args) throws Exception {
        if (args == null || args.length == 0 || args[0].equals("--help") || args[0].equals("-h")) {
            System.out.println("""
                    CLI Tags:
                        --help, -h              Display this message.
                        --list-conversions, -l  Display a list of supported conversions.
                                       
                    CLI Arguments:
                        0: currency_to:str           The 3 character currency code, to which the amount is to be converted.
                        1: currency_from=INR:str     The 3 character currency code, from which the amount is to be converted.
                        2: base_value=1.0:double     The amount to be converted.
                     """);
            return;
        }
        var result = new String(new URL("https://cdn.moneyconvert.net/api/latest.json").openConnection().getInputStream().readAllBytes());
        result = result.substring(30, result.length() - 52);
        Map<String, Double> map = Arrays.stream(result.split(", ")).map(s -> s.split(": "))
                .collect(Collectors.toMap(ss -> ss[0].replace("\"", ""), ss -> Double.parseDouble(ss[1])));
        if (args[0].equals("--list-conversions") || args[0].equals("-l")) {
            map.keySet().stream().sorted().forEach(System.out::println);
            return;
        }
        String currency_to = args[0];
        if (!map.containsKey(currency_to))
            System.out.println("There is no such currency code as " + currency_to + " in the database.");
        String currency_from = args.length >= 2 ? args[1] : "INR";
        if (!map.containsKey(currency_from))
            System.out.println("There is no such currency code as " + currency_from + " in the database.");
        double base = args.length >= 3 ? Double.parseDouble(args[2]) : 1.0;
        System.out.println(base * map.get(currency_to) / map.get(currency_from));
    }
}