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package java.lang.reflect;


TypeVariable is the common superinterface for type variables of kinds.
A type variable is created the first time it is needed by a reflective
method, as specified in this package.  If a type variable t is referenced
by a type (i.e, class, interface or annotation type) T, and T is declared
by the nth enclosing class of T (see JLS 8.1.2), then the creation of t
requires the resolution (see JVMS 5) of the ith enclosing class of T,
for i = 0 to n, inclusive. Creating a type variable must not cause the
creation of its bounds. Repeated creation of a type variable has no effect.

Multiple objects may be instantiated at run-time to
represent a given type variable. Even though a type variable is
created only once, this does not imply any requirement to cache
instances representing the type variable. However, all instances
representing a type variable must be equal() to each other.
As a consequence, users of type variables must not rely on the identity
of instances of classes implementing this interface.

Type parameters:
  • <D> – the type of generic declaration that declared the
underlying type variable.
@jls4.4 Type Variables
Since:1.5
/**
 * TypeVariable is the common superinterface for type variables of kinds.
 * A type variable is created the first time it is needed by a reflective
 * method, as specified in this package.  If a type variable t is referenced
 * by a type (i.e, class, interface or annotation type) T, and T is declared
 * by the nth enclosing class of T (see JLS 8.1.2), then the creation of t
 * requires the resolution (see JVMS 5) of the ith enclosing class of T,
 * for i = 0 to n, inclusive. Creating a type variable must not cause the
 * creation of its bounds. Repeated creation of a type variable has no effect.
 *
 * <p>Multiple objects may be instantiated at run-time to
 * represent a given type variable. Even though a type variable is
 * created only once, this does not imply any requirement to cache
 * instances representing the type variable. However, all instances
 * representing a type variable must be equal() to each other.
 * As a consequence, users of type variables must not rely on the identity
 * of instances of classes implementing this interface.
 *
 * @param <D> the type of generic declaration that declared the
 * underlying type variable.
 *
 * @jls 4.4 Type Variables
 * @since 1.5
 */
public interface TypeVariable<D extends GenericDeclaration> extends Type, AnnotatedElement {
    
Returns an array of Type objects representing the upper bound(s) of this type variable. If no upper bound is explicitly declared, the upper bound is Object. 
For each upper bound B: 
     
  • if B is a parameterized type or a type variable, it is created, (see ParameterizedType for the details of the creation process for parameterized types). 
  • Otherwise, B is resolved.  


Throws:
Returns:an array of Types representing the upper bound(s) of this type variable
/**
     * Returns an array of {@code Type} objects representing the
     * upper bound(s) of this type variable.  If no upper bound is
     * explicitly declared, the upper bound is {@code Object}.
     *
     * <p>For each upper bound B: <ul> <li>if B is a parameterized
     * type or a type variable, it is created, (see {@link
     * java.lang.reflect.ParameterizedType ParameterizedType} for the
     * details of the creation process for parameterized types).
     * <li>Otherwise, B is resolved.  </ul>
     *
     * @throws TypeNotPresentException  if any of the
     *     bounds refers to a non-existent type declaration
     * @throws MalformedParameterizedTypeException if any of the
     *     bounds refer to a parameterized type that cannot be instantiated
     *     for any reason
     * @return an array of {@code Type}s representing the upper
     *     bound(s) of this type variable
     */
    Type[] getBounds();

    
Returns the GenericDeclaration object representing the generic declaration declared for this type variable. 
Returns:the generic declaration declared for this type variable.
Since:1.5
/**
     * Returns the {@code GenericDeclaration} object representing the
     * generic declaration declared for this type variable.
     *
     * @return the generic declaration declared for this type variable.
     *
     * @since 1.5
     */
    D getGenericDeclaration();

    
Returns the name of this type variable, as it occurs in the source code.

Returns:the name of this type variable, as it appears in the source code
/**
     * Returns the name of this type variable, as it occurs in the source code.
     *
     * @return the name of this type variable, as it appears in the source code
     */
    String getName();

    
Returns an array of AnnotatedType objects that represent the use of types to denote the upper bounds of the type parameter represented by this TypeVariable. The order of the objects in the array corresponds to the order of the bounds in the declaration of the type parameter. Note that if no upper bound is explicitly declared, the upper bound is unannotated Object. 
Returns:an array of objects representing the upper bound(s) of the type variable
Since:1.8
/**
     * Returns an array of AnnotatedType objects that represent the use of
     * types to denote the upper bounds of the type parameter represented by
     * this TypeVariable. The order of the objects in the array corresponds to
     * the order of the bounds in the declaration of the type parameter. Note that
     * if no upper bound is explicitly declared, the upper bound is unannotated
     * {@code Object}.
     *
     * @return an array of objects representing the upper bound(s) of the type variable
     * @since 1.8
     */
     AnnotatedType[] getAnnotatedBounds();
}