Guice dependency injection choosing one of two implementations based on configuration

Question

I have two implementations of my service interface,

public interface Service {
   public ServiceResponse get();
}

One being a Mock implementation which returns a stubbed ServiceResponse and the other doing some real work with some unavailable downstream services.

Although both my RealService and MockService are ready I can only use the mock. And I want that instance to be injected depending on an environment variable. My question is how to achieve this?

Thanks

Answer 1

You can make an implementation of the Guice Provider interface that accesses the environment variable to determine which instance to provide. And then make injection use this provider by using ProviderBindings .