Reading environment variables in Dagger

Question

I'm relatively new to using Dagger and I have been reading up on the documentation here - https://google.github.io/dagger/users-guide . I was previously using Spring for DI. One thing which I was still not sure was - How to read environment variables in Dagger.

For example, in Spring, I'd just do:

@Value("${envVariable}")
private String myEnvVariable; 


@Bean 
public MyClass myclass() {

    return new MyClass().builder().property(myEnvVariable).build();
   }

I'm not sure if I'm somehow conflating the usage of Dagger as for reading environment variables.

I was assuming that in Dagger I'd have a Module which constructs the MyClass and then I'd use the @Inject annotation to inject the dependency, but wasn't sure how I'd get the value of the environment variable.

Answer 1

I ended up defining a method which would do something like this:

@Provides
@Named("ENV_VARIABLE_NAME")
@Singleton
public String getMyEnv() {
   return System.getenv("ENV_VARIABLE_NAME");
}

For usage, I have the @Named annotation, and therefore I'd just inject a String with the Named annotation in my other Module classes.