Converting classic nested for loops using java 8 streams

See English answers > Cartesian product of streams in Java 8 as streams (using streams only)

List<Card> deck = new ArrayList<>();
for (Suit s: Suit.values())
{
    for (Rank r: Rank.values())
    {
        deck .add(new Card(r,s));
    }
}

I'm out

List<Card> deck = new ArrayList<>();
Arrays.stream(Suit.values())
    .forEach(s -> Arrays.stream(Rank.values())
        .forEach(r -> deck.add(new Card(r,s))));

But I don't like it because it has side effects in the list

Is there another elegant way to generate lists from streams instead of?

Solution

use

List<Card> cards = Arrays.stream(Suit.values())
                .flatMap(s -> Arrays.stream(Rank.values()).map(r -> new Card(r,s)))
                .collect(Collectors.toList());

In fact, it is a simple Cartesian product I started with Cartesian product of streams in Java 8 as stream (using streams only) and adapted to your situation If you want to do the third loop in it, you need to use the code in this answer