TypeVariable


1   /*
2    * @(#)TypeVariable.java    1.3 04/01/12
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   
8   package java.lang.reflect;
9   
10  /**
11   * TypeVariable is the common superinterface for type variables of kinds.
12   * A type variable is created the first time it is needed by a reflective
13   * method, as specified in this package.  If a type variable t is referenced
14   * by a type (i.e, class, interface or annotation type) T, and T is declared
15   * by the nth enclosing class of T (see JLS 8.1.2), then the creation of t
16   * requires the resolution (see JVMS 5) of the ith enclosing class of T,
17   * for i = 0 to n, inclusive. Creating a type variable must not cause the
18   * creation of its bounds. Repeated creation of a type variable has no effect.
19   * 
20   * <p>Multiple objects may be instantiated at run-time to
21   * represent a given type variable. Even though a type variable is
22   * created only once, this does not imply any requirement to cache
23   * instances representing the type variable. However, all instances
24   * representing a type variable must be equal() to each other.
25   * As a consequence, users of type variables must not rely on the identity 
26   * of instances of classes implementing this interface.
27   *
28   * <p>The type parameter D represents the type of generic declaration
29   * that declared the underlying type variable.
30   *
31   * @since 1.5
32   */
33  public interface TypeVariable<D extends GenericDeclaration  > extends Type   {
34      /**
35       * Returns an array of <tt>Type</tt> objects representing the 
36       * upper bound(s) of this type variable.  Note that if no upper bound is
37       * explicitly declared, the upper bound is <tt>Object</tt>.
38       *
39       * <p>For each upper bound B: <ul> <li>if B is a parameterized
40       * type or a type variable, it is created, (see {@link
41       * java.lang.reflect.ParameterizedType ParameterizedType} for the
42       * details of the creation process for parameterized types).
43       * <li>Otherwise, B is resolved.  </ul>
44       *
45       * @throws TypeNotPresentException  if any of the
46       *     bounds refers to a non-existent type declaration
47       * @throws MalformedParameterizedTypeException if any of the 
48       *     bounds refer to a parameterized type that cannot be instantiated 
49       *     for any reason
50       * @return an array of <tt>Type</tt>s representing the upper
51       *     bound(s) of this type variable
52      */
53      Type  [] getBounds();
54  
55      /**
56       * Returns the <tt>GenericDeclaration</tt> object representing the 
57       * generic declaration declared this type variable.
58       *
59       * @return the generic declaration declared for this type variable.
60       *
61       * @since 1.5
62       */
63      D getGenericDeclaration();
64  
65      /**
66       * Returns the name of this type variable, as it occurs in the source code.
67       *
68       * @return the name of this type variable, as it appears in the source code
69       */
70      String   getName();
71  }
72  
73
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