java - what's the difference between these two binding declarations with Google Guice? -

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what's difference between

bind(fooimpl.class).in(scopes.singleton); bind(foo.class).to(fooimpl.class);

and

bind(foo.class).to(fooimpl.class).in(scopes.singleton);

with google guice?

edit:

the second declaration create 2 instances on singleton in project working on. reference here

in reference google guice documentation:

in linked bindings, scopes apply binding source, not binding target. suppose have class applebees implements both bar , grill interfaces. these bindings allow 2 instances of type, 1 bars , grills:

bind(bar.class).to(applebees.class).in(singleton.class); bind(grill.class).to(applebees.class).in(singleton.class);

this because scopes apply bound type (bar, grill), not type satisfies binding (applebees). allow single instance created, use @singleton annotation on declaration class. or add binding:

bind(applebees.class).in(singleton.class);

so, it's possible have 2 instances of fooimpl in second way not first way of writing binding.


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