001/* WildcardType.java -- A wildcard type expression e.g. ? extends String 002 Copyright (C) 2004, 2005 Free Software Foundation, Inc. 003 004This file is part of GNU Classpath. 005 006GNU Classpath is free software; you can redistribute it and/or modify 007it under the terms of the GNU General Public License as published by 008the Free Software Foundation; either version 2, or (at your option) 009any later version. 010 011GNU Classpath is distributed in the hope that it will be useful, but 012WITHOUT ANY WARRANTY; without even the implied warranty of 013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014General Public License for more details. 015 016You should have received a copy of the GNU General Public License 017along with GNU Classpath; see the file COPYING. If not, write to the 018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 01902110-1301 USA. 020 021Linking this library statically or dynamically with other modules is 022making a combined work based on this library. Thus, the terms and 023conditions of the GNU General Public License cover the whole 024combination. 025 026As a special exception, the copyright holders of this library give you 027permission to link this library with independent modules to produce an 028executable, regardless of the license terms of these independent 029modules, and to copy and distribute the resulting executable under 030terms of your choice, provided that you also meet, for each linked 031independent module, the terms and conditions of the license of that 032module. An independent module is a module which is not derived from 033or based on this library. If you modify this library, you may extend 034this exception to your version of the library, but you are not 035obligated to do so. If you do not wish to do so, delete this 036exception statement from your version. */ 037 038 039package java.lang.reflect; 040 041/** 042 * Represents a wildcard type expression, where the type variable 043 * is unnamed. The simplest example of this is <code>?</code>, 044 * which represents any unbounded type. Another example is 045 * <code>? extends Number</code>, which specifies any type 046 * which is a subclass of <code>Number</code> (<code>Number</code> 047 * is the upper bound). 048 * </p> 049 * <p> 050 * <code>? super String</code> gives the type a less common lower bound, 051 * which means that the type must be either a <code>String</code> or one 052 * of its superclasses. This can be useful in working with collections. 053 * You may want a method to add instances of a class to a collection 054 * with a more generic type (e.g. adding <code>String</code>s to 055 * a list of <code>Object</code>s), but don't want to allow users 056 * to pass in a collection with a more specific type. 057 * </p> 058 * 059 * @author Tom Tromey (tromey@redhat.com) 060 * @author Andrew John Hughes (gnu_andrew@member.fsf.org) 061 * @since 1.5 062 */ 063public interface WildcardType extends Type 064{ 065 066 /** 067 * <p> 068 * Returns an array of <code>Type</code>s, which specify the 069 * lower bounds of this type. The default lower bound is 070 * <code>null</code>, which causes this method to return an 071 * empty array. 072 * </p> 073 * <p> 074 * In generating the array of <code>Type</code>s, each 075 * <code>ParameterizedType</code> or <code>TypeVariable</code> is 076 * created, (see the documentation for these classes for details of this 077 * process), if necessary, while all other types are simply 078 * resolved. 079 * </p> 080 * 081 * @return an array of <code>Type</code> objects, representing 082 * the wildcard type's lower bounds. 083 * @throws TypeNotPresentException if any of the types referred to by 084 * the lower bounds of this type do not actually exist. 085 * @throws MalformedParameterizedTypeException if any of the types 086 * refer to a type which can not be instantiated. 087 */ 088 Type[] getLowerBounds(); 089 090 /** 091 * <p> 092 * Returns an array of <code>Type</code>s, which specify the 093 * upper bounds of this type. The default upper bound is 094 * <code>Object</code>, which causes this method to return an 095 * array, containing just the <code>Type</code> instance for 096 * <code>Object</code>. 097 * </p> 098 * <p> 099 * In generating the array of <code>Type</code>s, each 100 * <code>ParameterizedType</code> or <code>TypeVariable</code> is 101 * created, (see the documentation for these classes for details of this 102 * process), if necessary, while all other types are simply 103 * resolved. 104 * </p> 105 * 106 * @return an array of <code>Type</code> objects, representing 107 * the wildcard type's upper bounds. 108 * @throws TypeNotPresentException if any of the types referred to by 109 * the upper bounds of this type do not actually exist. 110 * @throws MalformedParameterizedTypeException if any of the types 111 * refer to a type which can not be instantiated. 112 */ 113 Type[] getUpperBounds(); 114 115}