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

Transcript

1. IT'S A KOTLIN, KOTLIN, KOTLIN WORLD! JAKE WHARTON PRESENTS
3. X
4. X O X X X O
5. X O X X X O O O X
6. XOPlayer X X X O O O X XOPlayer
7. iOS Web Server / API Android
8. app/
9. app/ wear/
10. app/ wear/ common/
11. app/ wear/ common/
12. wear/ common/ app/
13. app/ wear/ common/
14. app/ wear/ common/
15. app/ wear/ util/ common/
16. app/ wear/ common/ util/ models/
18. package xo; public enum Mark { X, O; }
19. 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);
20. 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(); }
21. package xo; public enum State { PLAYER_1_MOVE, PLAYER_2_MOVE, PLAYER_1_WIN, PLAYER_2_WIN, DRAW, }
22. 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)
23. Game Board Mark State Player
24. 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
25. 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
26. Game Mark State Board Player
27. State Board Game Mark Player
28. Game Mark State Board *.java *.kt Player
29. *.kt Game Mark State *.java
30. kotlinc *.kt Game Mark State *.java
31. *.kt Game Mark State *.java kotlinc
32. javac *.kt Game Mark State *.java kotlinc
33. javac *.kt Game Mark State *.java kotlinc
34. kotlinc javac *.kt Game Mark State *.java
35. kotlin-stdlib kotlinc javac *.kt Game Mark State *.java
36. kotlin-stdlib kotlinc javac *.kt Game Mark State *.java models/
37. kotlin-stdlib kotlinc javac *.kt Game Mark State *.java models/
38. kotlin-stdlib kotlinc javac *.kt Game Mark State *.java models/
39. kotlin-stdlib kotlinc javac *.kt Game Mark State *.java
40. kotlin-stdlib kotlinc Game Mark State javac *.kt *.java
41. kotlin-stdlib kotlinc Game Mark State javac *.kt *.java
42. kotlin-stdlib kotlinc State Mark Game javac *.kt *.java
43. kotlin-stdlib kotlinc State *.java Mark Game javac *.kt
44. kotlin-stdlib kotlinc *.java State Mark Game *.kt
45. app/ wear/ common/ util/ models/ kotlin-stdlib kotlinc *.java State Mark Game *.kt
46. app/ wear/ common/ util/ models/
47. Server / API iOS Web Android app/ wear/ common/ util/ models/
48. Server / API iOS Web Android app/ wear/ util/ models/ common/
49. Server / API iOS Web Android app/ wear/ util/ models/ common/
50. Server / API iOS Web Android app/ wear/ util/ models/ common/
51. Server / API iOS Web Android app/ wear/ util/ models/ common/ protos
52. iOS Web Server / API Android
53. iOS Web Server / API Android
54. iOS Web Server / API Android View Models
55. iOS Web Server / API Android View Models Presenters
56. iOS Web Server / API Android View Models Presenters
57. iOS Web Server / API Android View Models Presenters Client Backend
58. iOS Web Server / API Android View Models Presenters Client Backend
59. iOS Web Server / API Android View Models Presenters Client Backend Business Logic
60. iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
61. iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
62. data class NewGameUiModel( val winTotal: Long, val lossTotal: Long )
63. data class NewGameUiModel( val winTotal: Long, val lossTotal: Long ) data class GameUiModel( val game: Game )
64. data class NewGameUiModel( val winTotal: Long, val lossTotal: Long ) data class GameUiModel( ) val game: Game
65. data class NewGameUiModel( val winTotal: Long, val lossTotal: Long ) data class GameUiModel( val game: Game )
66. iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
67. iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
68. iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
69. class NewGamePresenter {C fun model(): NewGameUiModel { }B }A
70. class NewGamePresenter(private val gameStore: GameStore) {C fun model(): NewGameUiModel { }B }A
71. class NewGamePresenter(private val gameStore: GameStore) {C fun model(): NewGameUiModel { val totals = gameStore.totals() return NewGameUiModel(totals.wins, totals.losses) }B }A
72. class GamePresenter {D fun model(): GameUiModel {C }B }A
73. class GamePresenter(private val gameId: Long) {D fun model(): GameUiModel {C }B }A
74. class GamePresenter( private val gameId: Long, private val gameStore: GameStore ) {D fun model(): GameUiModel {C }B }A
75. class GamePresenter( private val gameId: Long, private val gameStore: GameStore ) {D fun models(): Observable<GameUiModel> {C }B }A
76. 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
77. 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
78. iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
79. iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
80. iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
81. iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
82. interface GameStore { }A
83. interface GameStore { fun totals(): Single<Totals> data class Totals(val wins: Long, val losses: Long) }A
84. interface GameStore { fun totals(): Single<Totals> fun game(id: Long): Observable<Game> data class Totals(val wins: Long, val losses: Long) }A
85. 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
86. iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
87. iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
88. Android iOS Web iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
89. 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() }
90. 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() }
91. 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
92. 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
93. 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
94. 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
95. Android iOS Web iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
96. Android iOS Web iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
97. Android iOS Web iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
98. Android iOS Web iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
99. 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() }
100. Android iOS Web iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
101. Android iOS Web iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
102. Android iOS Web iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
103. Android iOS Web iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
104. class GameView(context: Context, attrs: AttributeSet) : Consumer<GamePresenter.UiModel> { fun accept(model: GamePresenter.UiModel) { // TODO bind to view... } }
105. iOS???
106. function update(model) { // TODO bind to DOM/template/JSX/whatever... }
107. @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 ... }
108. Android iOS Web iOS Web Server / API Android View Models Presenters Client Backend Business Logic Models
109. X O X X X O O O X
110. IT'S A KOTLIN, KOTLIN, KOTLIN WORLD! @JAKEWHARTON