Package jakarta.ws.rs.core

Class GenericType<T>

java.lang.Object
jakarta.ws.rs.core.GenericType<T>
Type Parameters:
T - the generic type parameter.
Direct Known Subclasses:
SseEventOutputImpl
public class GenericType<T> extends Object
Represents a generic message entity type T. Supports in-line instantiation of objects that represent generic types with actual type parameters. An object that represents any parameterized type may be obtained by sub-classing GenericType. Alternatively, an object representing a concrete parameterized type can be created using a GenericType(java.lang.reflect.Type) and manually specifying the actual (parameterized) type.

For example: 

 GenericType<List<String>> stringListType = new GenericType<List<String>>() {
 };

Or: 

  public class MyGenericType extends GenericType<List<String>> { ... }

  ...

  MyGenericType stringListType = new MyGenericType();

Note that due to the Java type erasure limitations the parameterized type information must be specified on a subclass, not just during the instance creation. For example, the following case would throw an IllegalArgumentException: 

  public class MyGenericType<T> extends GenericType<T> { ... }

  ...

  // The type is only specified on instance, not in a sub-class
  MyGenericType<List<String>> stringListType =
          new MyGenericType<List<String>>();
Since:
2.0
Author:
Marek Potociar, Paul Sandoz, Martin Matula

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    GenericType()
    Constructs a new generic type, deriving the generic type and class from type parameter.
     
    GenericType(Type genericType)
    Constructs a new generic type, supplying the generic type information and deriving the class.

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    equals(Object obj)
     
    static GenericType
    forInstance(Object instance)
    Create a generic type from a Java instance.
    final Class<?>
    getRawType()
    Returns the object representing the class or interface that declared the type represented by this generic type instance.
    final Type
    getType()
    Retrieve the type represented by the generic type instance.
    int
    hashCode()
     
    String
    toString()
     

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • GenericType

      protected GenericType()
      Constructs a new generic type, deriving the generic type and class from type parameter. Note that this constructor is protected, users should create a (usually anonymous) subclass as shown above.
      Throws:
      IllegalArgumentException - in case the generic type parameter value is not provided by any of the subclasses.

    • GenericType

      public GenericType(Type genericType)
      Constructs a new generic type, supplying the generic type information and deriving the class.
      Parameters:
      genericType - the generic type.
      Throws:
      IllegalArgumentException - if genericType is null or not an instance of Class or ParameterizedType whose raw type is an instance of Class.

  • Method Details

    • forInstance

      public static GenericType forInstance(Object instance)
      Create a generic type from a Java instance.

      If the supplied instance is a GenericEntity, the generic type will be computed using the GenericEntity.getType(). Otherwise instance.getClass() will be used.

      Parameters:
      instance - Java instance for which the GenericType description should be created.
      Returns:
      GenericType describing the Java instance.
      Since:
      2.1

    • getType

      public final Type getType()
      Retrieve the type represented by the generic type instance.
      Returns:
      the actual type represented by this generic type instance.

    • getRawType

      public final Class<?> getRawType()
      Returns the object representing the class or interface that declared the type represented by this generic type instance.
      Returns:
      the class or interface that declared the type represented by this generic type instance.

    • equals

      public boolean equals(Object obj)
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • toString

      public String toString()
      Overrides:
      toString in class Object