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Java > Open Source Codes > org > apache > commons > collections > primitives > CharCollections


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17 package org.apache.commons.collections.primitives;
18
19 import org.apache.commons.collections.primitives.decorators.UnmodifiableCharIterator;
20 import org.apache.commons.collections.primitives.decorators.UnmodifiableCharList;
21 import org.apache.commons.collections.primitives.decorators.UnmodifiableCharListIterator;
22
23 /**
24  * This class consists exclusively of static methods that operate on or
25  * return CharCollections.
26  * <p>
27  * The methods of this class all throw a NullPoCharerException if the
28  * provided collection is null.
29  *
30  * @version $Revision: 480460 $ $Date: 2006-11-29 00:14:21 -0800 (Wed, 29 Nov 2006) $
31  *
32  * @author Rodney Waldhoff
33  */
34 public final class CharCollections {
35
36     /**
37      * Returns an unmodifiable CharList containing only the specified element.
38      * @param value the single value
39      * @return an unmodifiable CharList containing only the specified element.
40      */
41     public static CharList singletonCharList(char value) {
42         // TODO: a specialized implementation of CharList may be more performant
43 CharList list = new ArrayCharList(1);
44         list.add(value);
45         return UnmodifiableCharList.wrap(list);
46     }
47
48     /**
49      * Returns an unmodifiable CharIterator containing only the specified element.
50      * @param value the single value
51      * @return an unmodifiable CharIterator containing only the specified element.
52      */
53     public static CharIterator singletonCharIterator(char value) {
54         return singletonCharList(value).iterator();
55     }
56
57     /**
58      * Returns an unmodifiable CharListIterator containing only the specified element.
59      * @param value the single value
60      * @return an unmodifiable CharListIterator containing only the specified element.
61      */
62     public static CharListIterator singletonCharListIterator(char value) {
63         return singletonCharList(value).listIterator();
64     }
65
66     /**
67      * Returns an unmodifiable version of the given non-null CharList.
68      * @param list the non-null CharList to wrap in an unmodifiable decorator
69      * @return an unmodifiable version of the given non-null CharList
70      * @throws NullPointerException if the given CharList is null
71      * @see org.apache.commons.collections.primitives.decorators.UnmodifiableCharList#wrap
72      */
73     public static CharList unmodifiableCharList(CharList list) throws NullPointerException JavaDoc {
74         if(null == list) {
75             throw new NullPointerException JavaDoc();
76         }
77         return UnmodifiableCharList.wrap(list);
78     }
79     
80     /**
81      * Returns an unmodifiable version of the given non-null CharIterator.
82      * @param iter the non-null CharIterator to wrap in an unmodifiable decorator
83      * @return an unmodifiable version of the given non-null CharIterator
84      * @throws NullPointerException if the given CharIterator is null
85      * @see org.apache.commons.collections.primitives.decorators.UnmodifiableCharIterator#wrap
86      */
87     public static CharIterator unmodifiableCharIterator(CharIterator iter) {
88         if(null == iter) {
89             throw new NullPointerException JavaDoc();
90         }
91         return UnmodifiableCharIterator.wrap(iter);
92     }
93         
94     /**
95      * Returns an unmodifiable version of the given non-null CharListIterator.
96      * @param iter the non-null CharListIterator to wrap in an unmodifiable decorator
97      * @return an unmodifiable version of the given non-null CharListIterator
98      * @throws NullPointerException if the given CharListIterator is null
99      * @see org.apache.commons.collections.primitives.decorators.UnmodifiableCharListIterator#wrap
100      */
101     public static CharListIterator unmodifiableCharListIterator(CharListIterator iter) {
102         if(null == iter) {
103             throw new NullPointerException JavaDoc();
104         }
105         return UnmodifiableCharListIterator.wrap(iter);
106     }
107     
108     /**
109      * Returns an unmodifiable, empty CharList.
110      * @return an unmodifiable, empty CharList.
111      * @see #EMPTY_CHAR_LIST
112      */
113     public static CharList getEmptyCharList() {
114         return EMPTY_CHAR_LIST;
115     }
116     
117     /**
118      * Returns an unmodifiable, empty CharIterator
119      * @return an unmodifiable, empty CharIterator.
120      * @see #EMPTY_CHAR_ITERATOR
121      */
122     public static CharIterator getEmptyCharIterator() {
123         return EMPTY_CHAR_ITERATOR;
124     }
125     
126     /**
127      * Returns an unmodifiable, empty CharListIterator
128      * @return an unmodifiable, empty CharListIterator.
129      * @see #EMPTY_CHAR_LIST_ITERATOR
130      */
131     public static CharListIterator getEmptyCharListIterator() {
132         return EMPTY_CHAR_LIST_ITERATOR;
133     }
134
135     /**
136      * An unmodifiable, empty CharList
137      * @see #getEmptyCharList
138      */
139     public static final CharList EMPTY_CHAR_LIST = unmodifiableCharList(new ArrayCharList(0));
140
141     /**
142      * An unmodifiable, empty CharIterator
143      * @see #getEmptyCharIterator
144      */
145     public static final CharIterator EMPTY_CHAR_ITERATOR = unmodifiableCharIterator(EMPTY_CHAR_LIST.iterator());
146
147     /**
148      * An unmodifiable, empty CharListIterator
149      * @see #getEmptyCharListIterator
150      */
151     public static final CharListIterator EMPTY_CHAR_LIST_ITERATOR = unmodifiableCharListIterator(EMPTY_CHAR_LIST.listIterator());
152 }
153
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