001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *     http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.commons.collections.primitives;
018    
019    import org.apache.commons.collections.primitives.decorators.UnmodifiableShortIterator;
020    import org.apache.commons.collections.primitives.decorators.UnmodifiableShortList;
021    import org.apache.commons.collections.primitives.decorators.UnmodifiableShortListIterator;
022    
023    /**
024     * This class consists exclusively of static methods that operate on or
025     * return ShortCollections.
026     * <p>
027     * The methods of this class all throw a NullPoShorterException if the 
028     * provided collection is null.
029     * 
030     * @version $Revision: 480460 $ $Date: 2006-11-29 09:14:21 +0100 (Wed, 29 Nov 2006) $
031     * 
032     * @author Rodney Waldhoff 
033     */
034    public final class ShortCollections {
035    
036        /**
037         * Returns an unmodifiable ShortList containing only the specified element.
038         * @param value the single value
039         * @return an unmodifiable ShortList containing only the specified element.
040         */    
041        public static ShortList singletonShortList(short value) {
042            // TODO: a specialized implementation of ShortList may be more performant
043            ShortList list = new ArrayShortList(1);
044            list.add(value);
045            return UnmodifiableShortList.wrap(list);
046        }
047    
048        /**
049         * Returns an unmodifiable ShortIterator containing only the specified element.
050         * @param value the single value
051         * @return an unmodifiable ShortIterator containing only the specified element.
052         */    
053        public static ShortIterator singletonShortIterator(short value) {
054            return singletonShortList(value).iterator();
055        }
056    
057        /**
058         * Returns an unmodifiable ShortListIterator containing only the specified element.
059         * @param value the single value
060         * @return an unmodifiable ShortListIterator containing only the specified element.
061         */    
062        public static ShortListIterator singletonShortListIterator(short value) {
063            return singletonShortList(value).listIterator();
064        }
065    
066        /**
067         * Returns an unmodifiable version of the given non-null ShortList.
068         * @param list the non-null ShortList to wrap in an unmodifiable decorator
069         * @return an unmodifiable version of the given non-null ShortList
070         * @throws NullPointerException if the given ShortList is null
071         * @see org.apache.commons.collections.primitives.decorators.UnmodifiableShortList#wrap
072         */    
073        public static ShortList unmodifiableShortList(ShortList list) throws NullPointerException {
074            if(null == list) {
075                throw new NullPointerException();
076            }
077            return UnmodifiableShortList.wrap(list);
078        }
079        
080        /**
081         * Returns an unmodifiable version of the given non-null ShortIterator.
082         * @param iter the non-null ShortIterator to wrap in an unmodifiable decorator
083         * @return an unmodifiable version of the given non-null ShortIterator
084         * @throws NullPointerException if the given ShortIterator is null
085         * @see org.apache.commons.collections.primitives.decorators.UnmodifiableShortIterator#wrap
086         */    
087        public static ShortIterator unmodifiableShortIterator(ShortIterator iter) {
088            if(null == iter) {
089                throw new NullPointerException();
090            }
091            return UnmodifiableShortIterator.wrap(iter);
092        }
093            
094        /**
095         * Returns an unmodifiable version of the given non-null ShortListIterator.
096         * @param iter the non-null ShortListIterator to wrap in an unmodifiable decorator
097         * @return an unmodifiable version of the given non-null ShortListIterator
098         * @throws NullPointerException if the given ShortListIterator is null
099         * @see org.apache.commons.collections.primitives.decorators.UnmodifiableShortListIterator#wrap
100         */    
101        public static ShortListIterator unmodifiableShortListIterator(ShortListIterator iter) {
102            if(null == iter) {
103                throw new NullPointerException();
104            }
105            return UnmodifiableShortListIterator.wrap(iter);
106        }
107        
108        /**
109         * Returns an unmodifiable, empty ShortList.
110         * @return an unmodifiable, empty ShortList.
111         * @see #EMPTY_SHORT_LIST
112         */    
113        public static ShortList getEmptyShortList() {
114            return EMPTY_SHORT_LIST;
115        }
116        
117        /**
118         * Returns an unmodifiable, empty ShortIterator
119         * @return an unmodifiable, empty ShortIterator.
120         * @see #EMPTY_SHORT_ITERATOR
121         */    
122        public static ShortIterator getEmptyShortIterator() {
123            return EMPTY_SHORT_ITERATOR;
124        }
125        
126        /**
127         * Returns an unmodifiable, empty ShortListIterator
128         * @return an unmodifiable, empty ShortListIterator.
129         * @see #EMPTY_SHORT_LIST_ITERATOR
130         */    
131        public static ShortListIterator getEmptyShortListIterator() {
132            return EMPTY_SHORT_LIST_ITERATOR;
133        }    
134    
135        /**
136         * An unmodifiable, empty ShortList
137         * @see #getEmptyShortList
138         */    
139        public static final ShortList EMPTY_SHORT_LIST = unmodifiableShortList(new ArrayShortList(0));
140    
141        /**
142         * An unmodifiable, empty ShortIterator
143         * @see #getEmptyShortIterator
144         */    
145        public static final ShortIterator EMPTY_SHORT_ITERATOR = unmodifiableShortIterator(EMPTY_SHORT_LIST.iterator());
146    
147        /**
148         * An unmodifiable, empty ShortListIterator
149         * @see #getEmptyShortListIterator
150         */    
151        public static final ShortListIterator EMPTY_SHORT_LIST_ITERATOR = unmodifiableShortListIterator(EMPTY_SHORT_LIST.listIterator());
152    }