guice multibinder with Providers

Question

I am trying to be able to have this in my code

@Inject
private Map> providers;

I was trying but thi

Answer 1

Though Guice seems to be very good about using JSR-330 annotations interchangeably, it seems that Multibindings hides the Provider type within a Map and therefore may be expecting to inject a java.util.Map<java.lang.String, com.google.inject.Provider<...>> instead. I haven't been able to reproduce your problem, but try that and see if it helps.

Side note: If you want to avoid changing it in code everywhere, you can hackishly bind a provider of Map<String, javax.inject.Provider<Foo>> to something that takes in the multibinder-created Map<String, com.google.inject.Provider<Foo>>. If I'm right and this is the problem, you can fix it one place rather than bouncing between javax.inject and com.google.inject everywhere.

Answer 2

If you want Map<String, Provider<Processor>> at the injection point, the way to bind it is:

MapBinder<String, Processor> mapbinder = MapBinder.newMapBinder(binder, String.class, Processor.class); mapbinder.addBinding("splineV1Beta").to(SplineProcessor.class); mapbinder.addBinding("invertV1Beta").to(InvertProcessor.class);

You would use toProvider() if you are supplying a custom provider, which you are not, i.e. you are merely trying to use the implicit underlying provider.