Top Description Fields Constructors Methods
com.google.inject

public Class TypeLiteral<T>

extends Object
Class Inheritance
Static Imports
com.google.common.base.Preconditions.checkArgument, .Preconditions.checkNotNull, com.google.inject.internal.MoreTypes.canonicalize
Represents a generic type T. Java doesn't yet provide a way to represent generic types, so this class does. Forces clients to create a subclass of this class which enables retrieval of the type information even at runtime.

For example, to create a type literal for List<String>, you can create an empty anonymous inner class:

TypeLiteral<List<String>> list = new TypeLiteral<List<String>>() {};

Along with modeling generic types, this class can resolve type parameters. For example, to figure out what type keySet() returns on a Map<Integer, String>, use this code: 

TypeLiteral<Map<Integer, String>> mapType
    = new TypeLiteral<Map<Integer, String>>() {};
TypeLiteral<?> keySetType
    = mapType.getReturnType(Map.class.getMethod("keySet"));
System.out.println(keySetType); // prints "Set<Integer>"
Authors
[email protected] (Bob Lee), [email protected] (Jesse Wilson)

Field Summary

Modifier and TypeField and Description
pack-priv final int
hashCode

pack-priv final Class<? super T>
rawType

pack-priv final Type
type

Constructor Summary

AccessConstructor and Description
protected
TypeLiteral()

Constructs a new type literal.

pack-priv
TypeLiteral(Type type)

Unsafe.

Method Summary

Modifier and TypeMethod and Description
public final boolean
equals(Object
the reference object with which to compare.
o)

Overrides java.lang.Object.equals.

Indicates whether some other object is "equal to" this one.
pack-priv static TypeLiteral<?>
fromSuperclassTypeParameter(Class<?> subclass)

Gets type literal from super class's type parameter.

public static TypeLiteral<?>
get(Type type)

Gets type literal for the given Type instance.

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

Gets type literal for the given Class instance.

public List<TypeLiteral<?>>
getExceptionTypes(Member
a method or constructor defined by this or any supertype.
methodOrConstructor)

Returns the resolved generic exception types thrown by constructor.

public TypeLiteral<?>
getFieldType(Field
a field defined by this or any superclass.
field)

Returns the resolved generic type of field.

public List<TypeLiteral<?>>
getParameterTypes(Member
a method or constructor defined by this or any supertype.
methodOrConstructor)

Returns the resolved generic parameter types of methodOrConstructor.

public final Class<? super T>
getRawType()

Returns the raw (non-generic) type for this type.

public TypeLiteral<?>
getReturnType(Method
a method defined by this or any supertype.
method)

Returns the resolved generic return type of method.

pack-priv static Type
getSuperclassTypeParameter(Class<?> subclass)

Returns the type from super class's type parameter in canonical form.

public TypeLiteral<?>
getSupertype(Class<?>
a superclass of, or interface implemented by, this.
supertype)

Returns the generic form of supertype.

public final Type
getType()

Gets underlying Type instance.

public final int
hashCode()

Overrides java.lang.Object.hashCode.

Returns a hash code value for this object.
pack-priv final TypeLiteral<Provider<T>>
providerType()

Gets the type of this type's provider.

pack-priv TypeLiteral<?>
resolve(Type toResolve)

Resolves known type parameters in toResolve and returns the result.

private List<TypeLiteral<?>>
resolveAll(Type[] types)

Returns an immutable list of the resolved types.

pack-priv Type
resolveType(Type toResolve)

public final String
toString()

Overrides java.lang.Object.toString.

Returns a string representation of the object.
Inherited from java.lang.Object:
clonefinalizegetClassnotifynotifyAllwaitwaitwait

Field Detail

hashCodeback to summary
pack-priv final int hashCode
rawTypeback to summary
pack-priv final Class<? super T> rawType
typeback to summary
pack-priv final Type type

Constructor Detail

TypeLiteralback to summary
protected TypeLiteral()

Constructs a new type literal. Derives represented class from 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.

Annotations
@SuppressWarnings:unchecked
TypeLiteralback to summary
pack-priv TypeLiteral(Type type)

Unsafe. Constructs a type literal manually.

Annotations
@SuppressWarnings:unchecked

Method Detail

equalsback to summary
public final boolean equals(Object o)

Overrides java.lang.Object.equals.

Doc from java.lang.Object.equals.

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

  • It is reflexive: for any non-null reference value x, x.equals(x) should return true.
  • It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
  • It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
  • It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
  • For any non-null reference value x, x.equals(null) should return false.

An equivalence relation partitions the elements it operates on into equivalence classes; all the members of an equivalence class are equal to each other. Members of an equivalence class are substitutable for each other, at least for some purposes.

Parameters
o:Object

the reference object with which to compare.

Returns:boolean

true if this object is the same as the obj argument; false otherwise.

Annotations
@Override
fromSuperclassTypeParameterback to summary
pack-priv static TypeLiteral<?> fromSuperclassTypeParameter(Class<?> subclass)

Gets type literal from super class's type parameter.

getback to summary
public static TypeLiteral<?> get(Type type)

Gets type literal for the given Type instance.

getback to summary
public static <T> TypeLiteral<T> get(Class<T> type)

Gets type literal for the given Class instance.

getExceptionTypesback to summary
public List<TypeLiteral<?>> getExceptionTypes(Member methodOrConstructor)

Returns the resolved generic exception types thrown by constructor.

Parameters
methodOrConstructor:Member

a method or constructor defined by this or any supertype.

Since
2.0
getFieldTypeback to summary
public TypeLiteral<?> getFieldType(Field field)

Returns the resolved generic type of field.

Parameters
field:Field

a field defined by this or any superclass.

Since
2.0
getParameterTypesback to summary
public List<TypeLiteral<?>> getParameterTypes(Member methodOrConstructor)

Returns the resolved generic parameter types of methodOrConstructor.

Parameters
methodOrConstructor:Member

a method or constructor defined by this or any supertype.

Since
2.0
getRawTypeback to summary
public final Class<? super T> getRawType()

Returns the raw (non-generic) type for this type.

Since
2.0
getReturnTypeback to summary
public TypeLiteral<?> getReturnType(Method method)

Returns the resolved generic return type of method.

Parameters
method:Method

a method defined by this or any supertype.

Since
2.0
getSuperclassTypeParameterback to summary
pack-priv static Type getSuperclassTypeParameter(Class<?> subclass)

Returns the type from super class's type parameter in canonical form.

getSupertypeback to summary
public TypeLiteral<?> getSupertype(Class<?> supertype)

Returns the generic form of supertype. For example, if this is ArrayList<String>, this returns Iterable<String> given the input Iterable.class.

Parameters
supertype:Class<?>

a superclass of, or interface implemented by, this.

Since
2.0
getTypeback to summary
public final Type getType()

Gets underlying Type instance.

hashCodeback to summary
public final int hashCode()

Overrides java.lang.Object.hashCode.

Doc from java.lang.Object.hashCode.

Returns a hash code value for this object. This method is supported for the benefit of hash tables such as those provided by java.util.HashMap.

The general contract of hashCode is:

  • Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
  • If two objects are equal according to the equals method, then calling the hashCode method on each of the two objects must produce the same integer result.
  • It is not required that if two objects are unequal according to the equals method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.
Returns:int

a hash code value for this object

Annotations
@Override
providerTypeback to summary
pack-priv final TypeLiteral<Provider<T>> providerType()

Gets the type of this type's provider.

Annotations
@SuppressWarnings:unchecked
resolveback to summary
pack-priv TypeLiteral<?> resolve(Type toResolve)

Resolves known type parameters in toResolve and returns the result.

resolveAllback to summary
private List<TypeLiteral<?>> resolveAll(Type[] types)

Returns an immutable list of the resolved types.

resolveTypeback to summary
pack-priv Type resolveType(Type toResolve)
toStringback to summary
public final String toString()

Overrides java.lang.Object.toString.

Doc from java.lang.Object.toString.

Returns a string representation of the object.

Returns:String

a string representation of the object

Annotations
@Override