1 package org.codehaus.mojo.apt;
2
3 /*
4 * The MIT License
5 *
6 * Copyright 2006-2008 The Codehaus.
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a copy of
9 * this software and associated documentation files (the "Software"), to deal in
10 * the Software without restriction, including without limitation the rights to
11 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
12 * of the Software, and to permit persons to whom the Software is furnished to do
13 * so, subject to the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be included in all
16 * copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
23 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
24 * SOFTWARE.
25 */
26
27 import java.util.ArrayList;
28 import java.util.Collection;
29 import java.util.Collections;
30 import java.util.HashSet;
31 import java.util.List;
32 import java.util.Set;
33
34 /**
35 * Provides utilities for working with collections.
36 *
37 * @author <a href="mailto:markhobson@gmail.com">Mark Hobson</a>
38 * @version $Id: CollectionUtils.java 7031 2008-05-22 09:41:31Z mark $
39 */
40 public final class CollectionUtils
41 {
42 // constructors -----------------------------------------------------------
43
44 private CollectionUtils()
45 {
46 throw new AssertionError();
47 }
48
49 // public methods ---------------------------------------------------------
50
51 public static <T> Set<T> defaultSet( Set<T> set )
52 {
53 return defaultSet( set, Collections.<T>emptySet() );
54 }
55
56 public static <T> Set<T> defaultSet( Set<T> set, Set<T> defaultSet )
57 {
58 return isEmpty( set ) ? defaultSet : set;
59 }
60
61 public static boolean isEmpty( Collection<?> collection )
62 {
63 return ( collection == null ) || collection.isEmpty();
64 }
65
66 public static <E> Set<E> genericSet( Set<?> set, Class<E> elementType )
67 {
68 return genericCollection( set, elementType, new HashSet<E>() );
69 }
70
71 public static <E> List<E> genericList( List<?> list, Class<E> elementType )
72 {
73 return genericCollection( list, elementType, new ArrayList<E>() );
74 }
75
76 // private methods --------------------------------------------------------
77
78 private static <T extends Collection<E>, E> T genericCollection( Collection<?> collection, Class<E> elementType,
79 T genericCollection )
80 {
81 for ( Object element : collection )
82 {
83 genericCollection.add( elementType.cast( element ) );
84 }
85
86 return genericCollection;
87 }
88 }