com.google.inject

Class Key<T>

java.lang.Object

com.google.inject.Key<T>

public class Key<T>
extends Object

Binding key consisting of an injection type and an optional annotation. Matches the type and annotation at a point of injection.

For example, Key.get(Service.class, Transactional.class) will match:

   @Inject
   public void setService(@Transactional Service service) {
     ...
   }
 

Key supports generic types via subclassing just like TypeLiteral.

Keys do not differentiate between primitive types (int, char, etc.) and their corresponding wrapper types (Integer, Character, etc.). Primitive types will be replaced with their wrapper types when keys are created.

Author:

crazybob@google.com (Bob Lee)

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Key() Constructs a new key.
protected	Key(Annotation annotation) Constructs a new key.
protected	Key(Class<? extends Annotation> annotationType) Constructs a new key.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	equals(Object o)
static <T> Key<T>	get(Class<T> type) Gets a key for an injection type.
static <T> Key<T>	get(Class<T> type, Annotation annotation) Gets a key for an injection type and an annotation.
static <T> Key<T>	get(Class<T> type, Class<? extends Annotation> annotationType) Gets a key for an injection type and an annotation type.
static Key<?>	get(Type type) Gets a key for an injection type.
static Key<?>	get(Type type, Annotation annotation) Gets a key for an injection type and an annotation.
static Key<?>	get(Type type, Class<? extends Annotation> annotationType) Gets a key for an injection type and an annotation type.
static <T> Key<T>	get(TypeLiteral<T> typeLiteral) Gets a key for an injection type.
static <T> Key<T>	get(TypeLiteral<T> typeLiteral, Annotation annotation) Gets a key for an injection type and an annotation.
static <T> Key<T>	get(TypeLiteral<T> typeLiteral, Class<? extends Annotation> annotationType) Gets a key for an injection type and an annotation type.
Annotation	getAnnotation() Gets the annotation.
Class<? extends Annotation>	getAnnotationType() Gets the annotation type.
TypeLiteral<T>	getTypeLiteral() Gets the key type.
boolean	hasAttributes() Returns true if this key has annotation attributes.
int	hashCode()
<T> Key<T>	ofType(Class<T> type) Returns a new key of the specified type with the same annotation as this key.
Key<?>	ofType(Type type) Returns a new key of the specified type with the same annotation as this key.
<T> Key<T>	ofType(TypeLiteral<T> type) Returns a new key of the specified type with the same annotation as this key.
String	toString()
Key<T>	withoutAttributes() Returns this key without annotation attributes, i.e.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Key

protected Key(Class<? extends Annotation> annotationType)

Constructs a new key. Derives the type from this class's type parameter.

Clients create an empty anonymous subclass. Doing so embeds the type parameter in the anonymous class's type hierarchy so we can reconstitute it at runtime despite erasure.

Example usage for a binding of type Foo annotated with @Bar:

new Key<Foo>(Bar.class) {}.

Key

protected Key(Annotation annotation)

Constructs a new key. Derives the type from this class's type parameter.

Clients create an empty anonymous subclass. Doing so embeds the type parameter in the anonymous class's type hierarchy so we can reconstitute it at runtime despite erasure.

Example usage for a binding of type Foo annotated with @Bar:

new Key<Foo>(new Bar()) {}.

Key

protected Key()

Constructs a new key. Derives the type from this class's type parameter.

Clients create an empty anonymous subclass. Doing so embeds the type parameter in the anonymous class's type hierarchy so we can reconstitute it at runtime despite erasure.

Example usage for a binding of type Foo:

new Key<Foo>() {}.

Method Detail

getTypeLiteral

public final TypeLiteral<T> getTypeLiteral()

Gets the key type.

getAnnotationType

public final Class<? extends Annotation> getAnnotationType()

Gets the annotation type.

getAnnotation

public final Annotation getAnnotation()

Gets the annotation.

equals

public final boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public final int hashCode()

Overrides:

hashCode in class Object

toString

public final String toString()

Overrides:

toString in class Object

get

public static <T> Key<T> get(Class<T> type)

Gets a key for an injection type.

get

public static <T> Key<T> get(Class<T> type,
             Class<? extends Annotation> annotationType)

Gets a key for an injection type and an annotation type.

get

public static <T> Key<T> get(Class<T> type,
             Annotation annotation)

Gets a key for an injection type and an annotation.

get

public static Key<?> get(Type type)

Gets a key for an injection type.

get

public static Key<?> get(Type type,
         Class<? extends Annotation> annotationType)

Gets a key for an injection type and an annotation type.

get

public static Key<?> get(Type type,
         Annotation annotation)

Gets a key for an injection type and an annotation.

get

public static <T> Key<T> get(TypeLiteral<T> typeLiteral)

Gets a key for an injection type.

get

public static <T> Key<T> get(TypeLiteral<T> typeLiteral,
             Class<? extends Annotation> annotationType)

Gets a key for an injection type and an annotation type.

get

public static <T> Key<T> get(TypeLiteral<T> typeLiteral,
             Annotation annotation)

Gets a key for an injection type and an annotation.

ofType

public <T> Key<T> ofType(Class<T> type)

Returns a new key of the specified type with the same annotation as this key.

Since:

3.0

ofType

public Key<?> ofType(Type type)

Returns a new key of the specified type with the same annotation as this key.

Since:

3.0

ofType

public <T> Key<T> ofType(TypeLiteral<T> type)

Returns a new key of the specified type with the same annotation as this key.

Since:

3.0

hasAttributes

public boolean hasAttributes()

Returns true if this key has annotation attributes.

Since:

3.0

withoutAttributes

public Key<T> withoutAttributes()

Returns this key without annotation attributes, i.e. with only the annotation type.

Since:

3.0