Java 8 functional play

Factorial.java

import java.math.BigInteger;
import java.util.stream.IntStream;

public class Factorial {

    public static void main(String[] args) {
        System.out.println(Factorial.factorial(1));
        System.out.println(Factorial.factorial(5));
        System.out.println(Factorial.factorial(120000));
    }

    public static BigInteger factorial(final int num) {
        return IntStream
                .rangeClosed(1, num)
                .mapToObj(intValue -> new BigInteger(String.valueOf(intValue)))
                .reduce(BigInteger::multiply)
                .get();
    }
}

ServerSentEvents.java

import com.google.gson.Gson;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.Map;

public class ServerSentEvents {

    public static void main(String[] args) throws IOException {
        InputStream inputStream = new URL("http://tiny-chat.herokuapp.com/subscribe/everyone").openStream();
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));


        bufferedReader.lines()
                .filter(line -> line.startsWith("data: "))
                .map(line -> line.substring(6))
                .map(ServerSentEvents::jsonAsMap)
                .map(body -> body.get("message"))
                .forEach(System.out::println);

    }

    private static Map jsonAsMap(String json) {
        Gson gson = new Gson();
        return gson.fromJson(json, Map.class);
    }
}