001 /* WildcardType.java -- A wildcard type expression e.g. ? extends String 002 Copyright (C) 2004, 2005 Free Software Foundation, Inc. 003 004 This file is part of GNU Classpath. 005 006 GNU Classpath is free software; you can redistribute it and/or modify 007 it under the terms of the GNU General Public License as published by 008 the Free Software Foundation; either version 2, or (at your option) 009 any later version. 010 011 GNU Classpath is distributed in the hope that it will be useful, but 012 WITHOUT ANY WARRANTY; without even the implied warranty of 013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014 General Public License for more details. 015 016 You should have received a copy of the GNU General Public License 017 along with GNU Classpath; see the file COPYING. If not, write to the 018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 019 02110-1301 USA. 020 021 Linking this library statically or dynamically with other modules is 022 making a combined work based on this library. Thus, the terms and 023 conditions of the GNU General Public License cover the whole 024 combination. 025 026 As a special exception, the copyright holders of this library give you 027 permission to link this library with independent modules to produce an 028 executable, regardless of the license terms of these independent 029 modules, and to copy and distribute the resulting executable under 030 terms of your choice, provided that you also meet, for each linked 031 independent module, the terms and conditions of the license of that 032 module. An independent module is a module which is not derived from 033 or based on this library. If you modify this library, you may extend 034 this exception to your version of the library, but you are not 035 obligated to do so. If you do not wish to do so, delete this 036 exception statement from your version. */ 037 038 039 package 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 */ 063 public 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 }