com.google.inject.multibindings.OptionalBinderBinding Maven / Gradle / Ivy
package com.google.inject.multibindings;
import com.google.inject.Binding;
import com.google.inject.Key;
import com.google.inject.spi.Element;
import com.google.inject.spi.Elements;
import java.util.Set;
/**
* A binding for a OptionalBinder.
*
* Although OptionalBinders may be injected through a variety of types
* {@code T}, {@code Optional}, {@code Optional>}, etc..), an
* OptionalBinderBinding exists only on the Binding associated with the
* {@code Optional} key. Other bindings can be validated to be derived from this
* OptionalBinderBinding using {@link #containsElement}.
*
* @param The fully qualified type of the optional binding, including Optional.
* For example: {@code Optional}.
*/
public interface OptionalBinderBinding {
/**
* Returns the {@link Key} for this binding.
*/
Key getKey();
/**
* Returns the keys of other bindings that represent this OptionalBinder. This will return an
* entry for {@code Optional>} and {@code
* Optional>}.
*/
Set> getAlternateKeys();
/**
* Returns the default binding (set by {@link OptionalBinder#setDefault}) if one exists or null
* if no default binding is set. This will throw {@link UnsupportedOperationException} if it is
* called on an element retrieved from {@link Elements#getElements}.
*
* The Binding's type will always match the type Optional's generic type. For example, if getKey
* returns a key of Optional<String>, then this will always return a
* Binding<String>.
*/
Binding getDefaultBinding();
/**
* Returns the actual binding (set by {@link OptionalBinder#setBinding}) or null if not set.
* This will throw {@link UnsupportedOperationException} if it is called on an element retrieved
* from {@link Elements#getElements}.
*
* The Binding's type will always match the type Optional's generic type. For example, if getKey
* returns a key of Optional<String>, then this will always return a
* Binding<String>.
*/
Binding getActualBinding();
/**
* Returns true if this OptionalBinder contains the given Element in order to build the optional
* binding or uses the given Element in order to support building and injecting its data. This
* will work for OptionalBinderBinding retrieved from an injector and
* {@link Elements#getElements}. Usually this is only necessary if you are working with elements
* retrieved from modules (without an Injector), otherwise {@link #getDefaultBinding} and
* {@link #getActualBinding} are better options.
*/
boolean containsElement(Element element);
}