filter a stream using collect() instead of filter()

lapots :

I have the list that contains data that looks like this

game_id | user_id | status
   1         1       STARTED
   2         1       FINISHED
   1         2       STARTED
   2         2       FINISHED

I want to collect this list into two maps (or in a single map if possible)

One map should keep mapping of user_id to number of the games that user played - basically games with finished statuses

user_id | finished_games
   1            1
   2            1

Another map should store user_id to all games count. It would look like this

user_id  | all_games
   1            2
   2            2

I do it like this (I removed game_id field as it is that not important in fact)

import java.util.*;
import java.util.stream.*;

public class MyClass {
    public static void main(String args[]) {
        List<Game> games = Arrays.asList(
            create("user-1", "STARTED"),
            create("user-2", "STARTED"),
            create("user-1", "FINISHED"),
            create("user-2", "FINISHED"),
            create("user-1", "FINISHED"),
            create("user-2", "FINISHED")
        );

        // expect user-1: all_games (3), finished_games (2)

        Map<String, Long> allGames = games
            .stream()
            .collect(Collectors.groupingBy(Game::getUserId, Collectors.counting()));
        System.out.println(allGames);

        Map<String, Long> finishedGames = games
            .stream()
            .filter(game -> game.battleStatus.equals("FINISHED"))
            .collect(Collectors.groupingBy(Game::getUserId, Collectors.counting()));
        System.out.println(finishedGames);

    }

    private static Game create(String id, String status) {
        Game game = new Game();
        game.userId = id;
        game.battleStatus = status;
        return game;
    }

    private static class Game {
        String userId;
        String battleStatus;

        public String getUserId() {
            return userId;
        }
    }
}

It seems to work fine. But when I calculate games with status, I filter in order to leave only items with FINISHED status.

Map<String, Long> finishedGames = games
    .stream()
    .filter(game -> game.battleStatus.equals("FINISHED"))
    .collect(Collectors.groupingBy(Game::getUserId, Collectors.counting()));

Is there a way to achieve that inside collect block instead of using filter?

ETO :

If you need to count both finished and unfinished games, then another groupingBy can help you:

Function<Game, Boolean> isFinished = game -> "FINISHED".equals(game.battleStatus);

Map<String, Map<Boolean, Long>> groupedGames = 
    games.stream()
         .collect(groupingBy(Game::getUserId, 
                      groupingBy(isFinished, counting())));

Or you may want to group by battleStatus itself:

Map<String, Map<String, Long>> groupedGames = 
    games.stream()
         .collect(groupingBy(Game::getUserId, 
                      groupingBy(game -> game.battleStatus, counting())));

I would even create a getter getBattleStatus() and then replace game -> game.battleStatus with method reference Game::getBattleStatus:

Map<String, Map<String, Long>> groupedGames = 
    games.stream()
         .collect(groupingBy(Game::getUserId, 
                      groupingBy(Game::getBattleStatus, counting())));

filter a stream using collect() instead of filter()

Guess you like