2016/02/17(Wed)に開催された potatotips #26 (http://connpass.com/event/25401/) での発表資料です。

1. Replace EventBus with
RxJava/RxAndroid
Hiroyuki Kusu ( @hkusu_ )
株式会社ゆめみ
2016/02/17 potatotips #26

2. Android 以外も色々やります。最近は主に JavaScript
( Node.js + ES2015 ) を書いてます。

3. greenrobot/EventBus
⇒ Replace with RxJava(RxAndroid)

4. app/build.gradle
dependencies {
// ...
compile 'io.reactivex:rxjava:1.1.0'
compile 'io.reactivex:rxandroid:1.1.0'
}

5. public class RxEventBus {
private final Subject<Object, Object> subject
= new SerializedSubject<>(PublishSubject.create());
public <T> Subscription onEvent(Class<T> clazz, Action1<T> handler) {
return subject
.ofType(clazz)
.subscribe(handler);
}
public void post(Object event) {
subject.onNext(event);
}
}
RxEventBus.java

6. public class RxEventBusProvider {
private static final RxEventBus rxEventBus = new RxEventBus();
public static RxEventBus provide(){
return rxEventBus;
}
}
RxEventBusProvider.java
※ providing the singleton instance

7. RxEventBus rxEventBus = RxEventBusProvider.provide();
rxEventBus.post(new ChangedEvent());
rxEventBus.onEvent(ChangedEvent.class, event -> {
// something..
});
※ applying Java8 & Retrolambda
Getting instance
Publish
Subscribe

8. Subscription subscription;
// ...
subscription = rxEventBus.onEvent(ChangedEvent.class, event -> {
// something..
});
// ...
subscription.unsubscribe();
Unsubscribe ( order not to leak)

9. Tips

10. public class RxEventBus {
private final Subject<Object, Object> subject
= new SerializedSubject<>(PublishSubject.create());
public <T> Subscription onEvent(Class<T> clazz, Action1<T> handler) {
return subject
.ofType(clazz)
.subscribe(handler);
}
public <T> Subscription onEventMainThread(Class<T> clazz, Action1<T> handler) {
return subject
.ofType(clazz)
.observeOn(AndroidSchedulers.mainThread())
.subscribe(handler);
}
public void post(Object event) {
subject.onNext(event);
}
}
Subscribing in the main thread

11. public class ChangedEvent {
private int id;
public ChangedEvent(int id) {
this.id = id;
}
public int getId() {
return id;
}
}
rxEventBus.post(new ChangedEvent(99));
rxEventBus.onEvent(ChangedEvent.class, event -> {
int id = event.getId();
// something..
});
Getting a value from the event

12. rxEventBus.onEvent(TodoRepository.ChangedEvent.class, event -> {
// something..
});
Create event as an inner class of the class to
publish (or subscribe) the event.
Because, it is unclear to post the event from
where(or to where).

13. Appendix
Providing a singleton instance
in Dagger2

14. @Module
public class AppModule {
@Provides
@Singleton
public RxEventBus provideRxEventBus(){
return new RxEventBus();
}
}
AppModule.java
@Component(modules = AppModule.class)
public interface AppComponent {
RxEventBus provideRxEventBus();
}
AppComponent.java

15. Getting instance
AppComponent appComponent = DaggerAppComponent.create();
// ...
RxEventBus rxEventBus = appComponent.provideRxEventBus();
In this example, Dagger2 looks redundant , but
redundant description can be reduced by
@inject annotation to the constructor.
See https://github.com/hkusu/android-dagger-rxjava-sample .

16. Sample code
hkusu/android-dagger-rxjava-sample

17. Thanks!