Monte Carlo Simulation with Stream API

import java.util.function.*;
import java.util.stream.*;
import static java.util.stream.Collectors.*;
import java.util.*;

public class MonteCarlo{

    private final static int N = 10_000_000;
    private final static Random  r = new Random();

    public static Map<Integer, Double> parallelDiceRolls() {

        double fraction = 1.0 / N;

        return IntStream.range(0, N)
            .parallel()
            .mapToObj(n -> twoDiceThrows())
            .collect(groupingBy(side -> side, summingDouble(n -> fraction)));
    }

    public static int twoDiceThrows() {
        return r.nextInt(6) + r.nextInt(6) + 2;
    }

    public static void main(String []args){
        System.out.println(parallelDiceRolls());
    }
}