Guice: Difference between Binder#bindConstant() and Binder#bind() ... toInstance

Question

I would like to ask what's the difference between

bindConstant().annotatedWith(Names.named("keepAliveInterval")).to(60);

and

bind(Integer.TYPE).annotatedWith(Names.named("keepAliveInterval")).toInstance(60);

I would like to load all my configuration properties with Names.bindProperties(binder(), prop); in my module and I discovered that it uses the latter one for binding properties.

Thanks, regards

Marek

Answer 1

I think reasons to use bindConstant() are:

• It requires that you use an annotated binding. You can't do bindConstant().to(foo). Since the types you bind with it are primitives and Strings, it's unlikely that an annotation-less binding would make sense for any of them.
• It requires less effort since you don't have to specify the type (by the way, bindConstant() binds an int to Integer.class rather than Integer.TYPE, not sure if that matters).

I think Names.bindProperties doesn't use bindConstant just because it's internal code and a little more code is OK to skip a step or two in the process of making a binding. In your own modules, I'd just use bindConstant because it's easy and more clear.