IMHO, it's a sort-of bug or a missing feature. There's no nice solution
for the problem described. Quite often, a class knows suitable defaults
for missing ctor parameters and something like this should be supported.
Probably @Nullable is fine the way it works, but then there should be an
@Optional annotation on arguments allowing both a binding to null and a
missing binding.
You can achieve something like
@Inject
public void injectWebServiceProperties(
@Optional @Named("akui.webServiceURL") String webServiceUrl,
@Optional @Named("akui.webServiceUsername") String webServiceUsername,
@Optional @Named("akui.webServicePassword") String webServicePassword) {
...
}
only using field injection, which is obviously a bad thing. I've already
ran into this several times and I don't think it's so rare it should be
ignored.
On 10-07-02 10:31, [email protected] wrote:
> On Jul 1, 3:30 pm, Jeremy Chone <[email protected]> wrote:
>> Is this a wanted feature or a bug? Is there any way to avoid to have
>> one setter per property while keeping any of them optional?
>
> It's a feature. Although they're frequently confused, 'optional=true'
> and @Nullable mean quite different things.
>
> '@Inject(optional=true)' means that the injector should suppress any
> error from not being able to fulfill the dependencies of an injection.
> The injector will try its best to find bindings, even if that involves
> creating just-in-time bindings. But if any of the parameters to a
> method cannot be satisfied, the entire call is skipped.
>
> '@Nullable' means that the injector will not report an error if a null
> value is returned by the binding for an injection. The binding must
> still exist. The only time @Nullable is useful is when you implement a
> provider method (@Provides) or a provider class that may return null.
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