Kotlin & Modern Libraries

Transcript

1. Kotlin & modern libraries @takuji31
2. @takuji31 (Takuji Nishibayashi) Application Engineer at Hatena
3. Loves (AVG 160)
4. Loves Kotlin
5. Kotlin
6. Kotlin 1.0.0 released
7. JVM Language by JetBrains
8. Like Swift syntax
9. Like Swift syntax Swift is Kotlin like syntax!
10. Java Interoperability
11. Less boilerplate code
12. Android ready
13. Pretty name
14. Kotlin + modern libraries = happy
15. Dagger2
16. Provides in module constructor
17. Java @Module
 public class AppModule {
 private final Context context;
 public AppModule(Context context) {
 this.context = context;
 }
 
 @Provides
 public Context context() {
 return context;
 }
 
 @Provides
 public NotificationManager notificationManager(Context context) {
 return (NotificationManager)context.getSystemService(Context.NOTIFICATION_SERVICE);
 }
 }

18. Kotlin (Provider methods) @Module
 class AppModule(
 val context: Context
 ) {
 @Provides fun context() : Context = context
 @Provides fun notificationManager(context: Context) : NotificationManager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
 }
19. Use property
20. Kotlin (Constructor property) @Module
 class AppModule(
 @get:Provides val context: Context
 ) {
 @Provides fun notificationManager(context: Context) : NotificationManager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
 }
21. Kotlin (Constructor property) @Module
 class AppModule(
 @get:Provides val context: Context,
 @get:Provides val notificationManager: NotificationManager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
 ) {
 }
22. Provides in component property
23. Java @Component(modules = AppModule.class)
 @Singleton
 public interface AppComponent {
 Context context();
 NotificationManager notificationManager();
 }

24. Kotlin (functions) @Singleton
 @Component(modules = arrayOf(AppModule::class))
 interface AppComponent {
 fun context(): Context
 fun notificationManager(): NotificationManager
 }
25. Use property
26. Kotlin (properties) @Singleton
 @Component(modules = arrayOf(AppModule::class))
 interface AppComponent {
 val context : Context
 val notificationManager : NotificationManager
 }
27. Realm
28. Constructor and properties
29. Primary constructor and default value
30. Java public class User extends RealmObject {
 @PrimaryKey private String uuid;
 private String name;
 
 public User() {
 this(UUID.randomUUID().toString(), null);
 }
 
 public User(String uuid, String name) {
 this.uuid = uuid;
 this.name = name;
 }
 
 public String getUuid() {return uuid;}
 public void setUuid(String uuid) {this.uuid = uuid;}
 public String getName() {return name;}
 public void setName(String name) {this.name = name;}
 }

31. Kotlin (default constructor) class User constructor() : RealmObject() {
 @PrimaryKey
 var uuid: String? = UUID.randomUUID().toString()
 var name: String? = null
 }

32. Kotlin (with default value) open class User(
 @PrimaryKey open var uuid: String = UUID.randomUUID().toString(),
 open var name: String? = null
 ) : RealmObject() {}
33. Computed property in model class
34. Use extension property
35. Java public class User extends RealmObject {
 private Date createdDate;
 @Ignore private Instant createdAt;
 
 public Date getCreatedDate() {return createdDate;}
 public void setCreatedDate(Date createdDate) {this.createdDate = createdDate;}
 public Instant getCreatedAt() {
 return DateTimeUtils.toInstant(getCreatedDate());
 }
 public void setCreatedAt(Instant createdAt) {
 setCreatedDate(DateTimeUtils.toDate(createdAt));
 }
 }
36. Kotlin (property) Not available
37. Kotlin (extension property) open class User( …
 open var createdDate: Date? = null
 ) : RealmObject() {} var User.createdAt : Instant
 get() = DateTimeUtils.toInstant(createdDate)
 set(value) {
 createdDate = DateTimeUtils.toDate(value)
 }
38. Enjoy Kotlin life!