How to send event from Service to Activity with Otto event bus?

Question

Simple BusProvider.getInstance().post() bring exception not main thread. How to send event from Service to Activity with Otto event bus?

Answer 1

To post from any thread (main or background) and receive on the main thread, try something like

public class MainThreadBus extends Bus {   private final Handler mHandler = new Handler(Looper.getMainLooper());    @Override   public void post(final Object event) {     if (Looper.myLooper() == Looper.getMainLooper()) {       super.post(event);     } else {       mHandler.post(new Runnable() {         @Override         public void run() {           MainThreadBus.super.post(event);         }       });     }   } } 

Note: credit goes to Jake Wharton and "pommedeterresaute" at https://github.com/square/otto/issues/38 for the general approach. I just implemented it with a wrapper class rather than a subclass.

Answer 2

To post from any thread (main or background) and receive on the main thread, use the following MainThreadBus instead of a vanilla Bus

public class MainThreadBus extends Bus {      private final Handler handler = new Handler(Looper.getMainLooper());       @Override public void post(final Object event) {         if (Looper.myLooper() == Looper.getMainLooper()) {             super.post(event);         } else {             handler.post(new Runnable() {                 @Override                 public void run() {                     MainThreadBus.super.post(event);                 }             });         }     } } 

This is based on Andy Dennie's answer.

There is no need to both extend and wrap a Bus object, do one or the other. In Dennie's answer, which is effectively a wrapper, the Bus base class is just being used like an interface, all the functionality is overwritten.

It would work even if you removed the Bus base class unless you happened to reference the MainThreadBus via a Bus reference.