java.lang.reflect

Interface WildcardType

All Superinterfaces:
Type

public interface WildcardType
extends Type

Represents a wildcard type expression, where the type variable is unnamed. The simplest example of this is ?, which represents any unbounded type. Another example is ? extends Number, which specifies any type which is a subclass of Number (Number is the upper bound).

? super String gives the type a less common lower bound, which means that the type must be either a String or one of its superclasses. This can be useful in working with collections. You may want a method to add instances of a class to a collection with a more generic type (e.g. adding Strings to a list of Objects), but don't want to allow users to pass in a collection with a more specific type.

Since:
1.5

Method Summary

Type[]
getLowerBounds()
Returns an array of Types, which specify the lower bounds of this type.
Type[]
getUpperBounds()
Returns an array of Types, which specify the upper bounds of this type.

Method Details

getLowerBounds

public Type[] getLowerBounds()
Returns an array of Types, which specify the lower bounds of this type. The default lower bound is null, which causes this method to return an empty array.

In generating the array of Types, each ParameterizedType or TypeVariable is created, (see the documentation for these classes for details of this process), if necessary, while all other types are simply resolved.

Returns:
an array of Type objects, representing the wildcard type's lower bounds.
Throws:
TypeNotPresentException - if any of the types referred to by the lower bounds of this type do not actually exist.
MalformedParameterizedTypeException - if any of the types refer to a type which can not be instantiated.

getUpperBounds

public Type[] getUpperBounds()
Returns an array of Types, which specify the upper bounds of this type. The default upper bound is Object, which causes this method to return an array, containing just the Type instance for Object.

In generating the array of Types, each ParameterizedType or TypeVariable is created, (see the documentation for these classes for details of this process), if necessary, while all other types are simply resolved.

Returns:
an array of Type objects, representing the wildcard type's upper bounds.
Throws:
TypeNotPresentException - if any of the types referred to by the upper bounds of this type do not actually exist.
MalformedParameterizedTypeException - if any of the types refer to a type which can not be instantiated.

WildcardType.java -- A wildcard type expression e.g. ? extends String Copyright (C) 2004, 2005 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.