How can I count the number of elements that match a predicate with Streams?

Question

In Java7 I have this code:

public int getPlayersOnline() {
    int count = 0;
    for (Player player : players) {
        if (player.isActive()) {
            count++;
        }
    }
    return count;
}

I'm trying to use Java 8 features as much as possible, how can I go about improving this with lambdas?

Answer 1

This would be a one-liner:

return (int) players.stream().filter(Player::isActive).count();