java.lang.Object
- com.google.inject.Key<T>

```
public class Key<T>
extends java.lang.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.

Constructor Summary

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

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`equals(java.lang.Object o)`
`static <T> Key<T>`	`get(TypeLiteral<T> typeLiteral)`	Gets a key for an injection type.
`static <T> Key<T>`	`get(TypeLiteral<T> typeLiteral, java.lang.annotation.Annotation annotation)`	Gets a key for an injection type and an annotation.
`static <T> Key<T>`	`get(TypeLiteral<T> typeLiteral, java.lang.Class<? extends java.lang.annotation.Annotation> annotationType)`	Gets a key for an injection type and an annotation type.
`static <T> Key<T>`	`get(java.lang.Class<T> type)`	Gets a key for an injection type.
`static <T> Key<T>`	`get(java.lang.Class<T> type, java.lang.annotation.Annotation annotation)`	Gets a key for an injection type and an annotation.
`static <T> Key<T>`	`get(java.lang.Class<T> type, java.lang.Class<? extends java.lang.annotation.Annotation> annotationType)`	Gets a key for an injection type and an annotation type.
`static Key<?>`	`get(java.lang.reflect.Type type)`	Gets a key for an injection type.
`static Key<?>`	`get(java.lang.reflect.Type type, java.lang.annotation.Annotation annotation)`	Gets a key for an injection type and an annotation.
`static Key<?>`	`get(java.lang.reflect.Type type, java.lang.Class<? extends java.lang.annotation.Annotation> annotationType)`	Gets a key for an injection type and an annotation type.
`java.lang.annotation.Annotation`	`getAnnotation()`	Gets the annotation instance if available.
`java.lang.Class<? extends java.lang.annotation.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()`
`<U> Key<U>`	`ofType(TypeLiteral<U> type)`	Returns a new key of the specified type with the same annotation as this key.
`<U> Key<U>`	`ofType(java.lang.Class<U> type)`	Returns a new key of the specified type with the same annotation as this key.
`Key<?>`	`ofType(java.lang.reflect.Type type)`	Returns a new key of the specified type with the same annotation as this key.
`java.lang.String`	`toString()`
`Key<T>`	`withAnnotation(java.lang.annotation.Annotation annotation)`	Returns a new key of the same type with the specified annotation.
`Key<T>`	`withAnnotation(java.lang.Class<? extends java.lang.annotation.Annotation> annotationType)`	Returns a new key of the same type with the specified annotation.
`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(java.lang.Class<? extends java.lang.annotation.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(java.lang.annotation.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 java.lang.Class<? extends java.lang.annotation.Annotation> getAnnotationType()
```
 Gets the annotation type. Will be null if this key lacks an annotation.
 - getAnnotation
```
public final java.lang.annotation.Annotation getAnnotation()
```
 Gets the annotation instance if available. Will be null if this key lacks an annotation or the key was constructed with a Class<Annotation>.
 Warning: this can return null even if this key is annotated. To check whether a Key has an annotation use hasAnnotationType() instead.
 - equals
```
public final boolean equals(java.lang.Object o)
```
 Overrides:
 
 equals in class java.lang.Object
 - hashCode
```
public final int hashCode()
```
 Overrides:
 
 hashCode in class java.lang.Object
 - toString
```
public final java.lang.String toString()
```
 Overrides:
 
 toString in class java.lang.Object
 - get
```
public static <T> Key<T> get(java.lang.Class<T> type)
```
 Gets a key for an injection type.
 - get
```
public static <T> Key<T> get(java.lang.Class<T> type,
 java.lang.Class<? extends java.lang.annotation.Annotation> annotationType)
```
 Gets a key for an injection type and an annotation type.
 - get
```
public static <T> Key<T> get(java.lang.Class<T> type,
 java.lang.annotation.Annotation annotation)
```
 Gets a key for an injection type and an annotation.
 - get
```
public static Key<?> get(java.lang.reflect.Type type)
```
 Gets a key for an injection type.
 - get
```
public static Key<?> get(java.lang.reflect.Type type,
 java.lang.Class<? extends java.lang.annotation.Annotation> annotationType)
```
 Gets a key for an injection type and an annotation type.
 - get
```
public static Key<?> get(java.lang.reflect.Type type,
 java.lang.annotation.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,
 java.lang.Class<? extends java.lang.annotation.Annotation> annotationType)
```
 Gets a key for an injection type and an annotation type.
 - get
```
public static <T> Key<T> get(TypeLiteral<T> typeLiteral,
 java.lang.annotation.Annotation annotation)
```
 Gets a key for an injection type and an annotation.
 - ofType
```
public  Key ofType(java.lang.Class type)
```
 Returns a new key of the specified type with the same annotation as this key.
 
 Since:
 
 3.0
 - ofType
```
public Key<?> ofType(java.lang.reflect.Type type)
```
 Returns a new key of the specified type with the same annotation as this key.
 
 Since:
 
 3.0
 - ofType
```
public  Key ofType(TypeLiteral type)
```
 Returns a new key of the specified type with the same annotation as this key.
 
 Since:
 
 3.0
 - withAnnotation
```
public Key<T> withAnnotation(java.lang.Class<? extends java.lang.annotation.Annotation> annotationType)
```
 Returns a new key of the same type with the specified annotation.
 This is equivalent to Key.get(key.getTypeLiteral(), annotation) but may be more convenient to use in certain cases.
 
 Since:
 
 5.0
 - withAnnotation
```
public Key<T> withAnnotation(java.lang.annotation.Annotation annotation)
```
 Returns a new key of the same type with the specified annotation.
 This is equivalent to Key.get(key.getTypeLiteral(), annotation) but may be more convenient to use in certain cases.
 
 Since:
 
 5.0
 - 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

Class Key<T>

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Key

Key

Key

Method Detail

getTypeLiteral

getAnnotationType

getAnnotation

equals

hashCode

toString

get

get

get

get

get

get

get

get

get

ofType

ofType

ofType

withAnnotation

withAnnotation

hasAttributes

withoutAttributes