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It's a Kotlin, Kotlin, Kotlin World (London And...

It's a Kotlin, Kotlin, Kotlin World (London Android Meetup July 2017)

Kotlin's popularity has exploded in the past year and Google's announcement of first-party support at I/O means it's only going to keep increasing. Now is the perfect time to jump on the language as its future in mobile and beyond is very bright. This talk will take a look at where the language is headed and see if it can deliver on a promise of cross-platform use.

Video: https://youtu.be/CtZL_IjR5Ww

Jake Wharton

July 25, 2017
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  1. X

  2. package xo; import java.util.Arrays; public final class Board { private

    static final int SIZE = 3; private final Mark[][] cells; public Board() { this.cells = new Mark[3][3]; } // TODO mutator methods... @Override public boolean equals(Object o) { if (this == o) return true; if (!(o instanceof Board)) return false; Board other = (Board) o; return Arrays.deepEquals(cells, other.cells); } @Override public int hashCode() { return Arrays.deepHashCode(cells);
  3. package xo; import static java.util.Objects.requireNonNull; public final class Player {

    public final String name; public final Mark mark; public Player(String name, Mark mark) { this.name = requireNonNull(name, "name == null"); this.mark = requireNonNull(mark, "mark == null"); } @Override public boolean equals(Object o) { if (this == o) return true; if (!(o instanceof Player)) return false; Player other = (Player) o; return name.equals(other.name) && mark == other.mark; } @Override public int hashCode() { return 31 * name.hashCode() + mark.hashCode(); }
  4. package xo; import static java.util.Objects.requireNonNull; public final class Game {

    private final Board board; private final Player player1; private final Player player2; private State state = State.PLAYER_1_MOVE; public Game(Board board, Player player1, Player player2) { this.board = requireNonNull(board, "board == null"); this.player1 = requireNonNull(player1, "player1 == null"); this.player2 = requireNonNull(player2, "player2 == null"); } // TODO mutator methods... @Override public boolean equals(Object o) { if (this == o) return true; if (!(o instanceof Game)) return false; Game other = (Game) o; return board.equals(other.board) && player1.equals(other.player1)
  5. public final class Player { public final String name; public

    final Mark mark; public Player(String name, Mark mark) { this.name = requireNonNull(name, "name == null"); this.mark = requireNonNull(mark, "mark == null"); }A @Override public boolean equals(Object o) { if (this == o) return true; if (!(o instanceof Player)) return false; Player other = (Player) o; return name.equals(other.name) && mark == other.mark; }B @Override public int hashCode() { return 31 * name.hashCode() + mark.hashCode(); }C @Override public String toString() { return "Player{name='" + name + ", mark=" + mark + '}'; }D }E
  6. data class Player(val name: String, val mark: Mark) public final

    { public final ; public final ; public Player(String name, Mark mark) { this.name = requireNonNull(name, "name == null"); this.mark = requireNonNull(mark, "mark == null"); }A @Override public boolean equals(Object o) { if (this == o) return true; if (!(o instanceof Player)) return false; Player other = (Player) o; return name.equals(other.name) && mark == other.mark; }B @Override public int hashCode() { return 31 * name.hashCode() + mark.hashCode(); }C @Override public String toString() { return "Player{name='" + name + ", mark=" + mark + '}'; }D }E
  7. class NewGamePresenter(private val gameStore: GameStore) {C fun model(): NewGameUiModel {

    val totals = gameStore.totals() return NewGameUiModel(totals.wins, totals.losses) }B }A
  8. class GamePresenter( private val gameId: Long, private val gameStore: GameStore

    ) {D fun models(): Observable<GameUiModel> {C }B }A
  9. class GamePresenter( private val gameId: Long, private val gameStore: GameStore

    ) {D fun move(row: Int, col: Int)Z{C }G fun models(): Observable<GameUiModel> {C }B }A
  10. class GamePresenter( private val gameId: Long, private val gameStore: GameStore

    ) {D fun models(events: Observable<UiEvent>): Observable<GameUiModel> {C }B sealed class UiEvent { data class Move(val row: Int, val col: Int): UiEvent() // ... } }A fun move( )Z{C }G
  11. interface GameStore { fun totals(): Single<Totals> fun game(id: Long): Observable<Game>

    fun move(id: Long, row: Int, col: Int): Completable data class Totals(val wins: Long, val losses: Long) }A
  12. Android iOS Web iOS Web Server / API Android View

    Models Presenters Client Backend Business Logic Models
  13. class SqliteGameStore(private val db: SQLiteDatabase) : GameStore { override fun

    totals() = TODO() override fun game(id: Long) = TODO() override fun move(id: Long, row: Int, col: Int) = TODO() }
  14. class IosGameStore(private val db: CoreDataGameStore) : GameStore { override fun

    totals() = TODO() override fun game(id: Long) = TODO() override fun move(id: Long, row: Int, col: Int) = TODO() }
  15. class IosGameStore( ) : GameStore { override fun totals() =

    TODO() override fun game(id: Long) = TODO() override fun move(id: Long, row: Int, col: Int) = TODO() } private val db: CoreDataGameStore
  16. class IosGameStore( ) : GameStore { override fun totals() =

    TODO() override fun game(id: Long) = TODO() override fun move(id: Long, row: Int, col: Int) = TODO() } private val db: CoreDataGameStore // tictactoe.def headers = game_store.h
  17. class StorageGameStore(private val store: Storage) : GameStore { override fun

    totals() = TODO() override fun game(id: Long) = TODO() override fun move(id: Long, row: Int, col: Int) = TODO() }A
  18. import org.w3c.dom.Storage class StorageGameStore( ) : GameStore { override fun

    totals() = TODO() override fun game(id: Long) = TODO() override fun move(id: Long, row: Int, col: Int) = TODO() }A private val store: Storage
  19. Android iOS Web iOS Web Server / API Android View

    Models Presenters Client Backend Business Logic Models
  20. Android iOS Web iOS Web Server / API Android View

    Models Presenters Client Backend Business Logic Models
  21. Android iOS Web iOS Web Server / API Android View

    Models Presenters Client Backend Business Logic Models
  22. Android iOS Web iOS Web Server / API Android View

    Models Presenters Client Backend Business Logic Models
  23. object TicTacToeLogic { fun validateMove( game: Game, player: Player, row:

    Int, col: Int): Boolean { when (game.state) { State.PLAYER_1_MOVE -> require(game.player1 == player) State.PLAYER_2_MOVE -> require(game.player2 == player) else -> error("Game is over") } return game.board[row][col] == null } fun nextState(game: Game): State { findWinner(game.board)?.let { return if (game.player1.mark == it) State.PLAYER_1_WIN else State.PLAYER_2_WIN } if (game.board.isComplete()) { return State.DRAW } return if (game.state == State.PLAYER_1_MOVE) State.PLAYER_2_MOVE else State.PLAYER_1_MOVE } fun findWinner(board: Board): Mark? = TODO() fun Board.isComplete(): Boolean = TODO() }
  24. Android iOS Web iOS Web Server / API Android View

    Models Presenters Client Backend Business Logic Models
  25. Android iOS Web iOS Web Server / API Android View

    Models Presenters Client Backend Business Logic Models
  26. Android iOS Web iOS Web Server / API Android View

    Models Presenters Client Backend Business Logic Models
  27. Android iOS Web iOS Web Server / API Android View

    Models Presenters Client Backend Business Logic Models
  28. @POST @Path("/api/move") fun Game move( @QueryParam("id") id: Long, @QueryParam("row") row:

    Int, @QueryParam("col") col: Int) { // TODO check business logic, persist, return udpated game ... }
  29. Android iOS Web iOS Web Server / API Android View

    Models Presenters Client Backend Business Logic Models