public final class OptionalConstructorParam<T> extends Object implements Supplier<T>
Workaround for optional constructor parameters with Guice. Modeled after the Guava Optional class, but you cannot create your own Optional because the constructor is private, so just adopting the look and feel of it.
Unfortunately, this does not support optional bindings which use @Named; that annotation on the value in the constructor, eg:
public Foo(@Named("bar") OptionalConstructorParam<MyObject> theParam)
Because the @Inject is inside OptionalConstructorParam and that's where the injection actually takes place, the @Named annotation is essentially ignored. If you could place @Named inside this class, with a parameterized value for the name, that would work as expected, but annotation values have to be consts, so there's no way to pass in the name to the annotation. So if you want to use @Named w/ an optional constructor parameter, you basically have to duplicate the Guice part of this class locally and use the @Named annotation explicitly.
Constructor and Description |
---|
OptionalConstructorParam() |
OptionalConstructorParam(T theValue) |
Modifier and Type | Method and Description |
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Optional<T> |
asOptional() |
static <T> OptionalConstructorParam<T> |
create(T theValue) |
boolean |
equals(Object o) |
T |
get() |
int |
hashCode() |
boolean |
isPresent() |
T |
or(Supplier<? extends T> theDefault) |
T |
or(T theDefault) |
T |
orNull() |
String |
toString() |
@Inject public OptionalConstructorParam()
public OptionalConstructorParam(T theValue)
public T orNull()
public boolean isPresent()
public static <T> OptionalConstructorParam<T> create(T theValue)
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