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| 1 | +/* | |
| 2 | + * Copyright (c) 1995, 2004, Oracle and/or its affiliates. All rights reserved. | |
| 3 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 | + * | |
| 5 | + * This code is free software; you can redistribute it and/or modify it | |
| 6 | + * under the terms of the GNU General Public License version 2 only, as | |
| 7 | + * published by the Free Software Foundation. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | + | |
| 26 | +package java.util; | |
| 27 | + | |
| 28 | +/** | |
| 29 | + * The <code>Dictionary</code> class is the abstract parent of any | |
| 30 | + * class, such as <code>Hashtable</code>, which maps keys to values. | |
| 31 | + * Every key and every value is an object. In any one <tt>Dictionary</tt> | |
| 32 | + * object, every key is associated with at most one value. Given a | |
| 33 | + * <tt>Dictionary</tt> and a key, the associated element can be looked up. | |
| 34 | + * Any non-<code>null</code> object can be used as a key and as a value. | |
| 35 | + * <p> | |
| 36 | + * As a rule, the <code>equals</code> method should be used by | |
| 37 | + * implementations of this class to decide if two keys are the same. | |
| 38 | + * <p> | |
| 39 | + * <strong>NOTE: This class is obsolete. New implementations should | |
| 40 | + * implement the Map interface, rather than extending this class.</strong> | |
| 41 | + * | |
| 42 | + * @author unascribed | |
| 43 | + * @see java.util.Map | |
| 44 | + * @see java.lang.Object#equals(java.lang.Object) | |
| 45 | + * @see java.lang.Object#hashCode() | |
| 46 | + * @see java.util.Hashtable | |
| 47 | + * @since JDK1.0 | |
| 48 | + */ | |
| 49 | +public abstract | |
| 50 | +class Dictionary<K,V> { | |
| 51 | + /** | |
| 52 | + * Sole constructor. (For invocation by subclass constructors, typically | |
| 53 | + * implicit.) | |
| 54 | + */ | |
| 55 | + public Dictionary() { | |
| 56 | + } | |
| 57 | + | |
| 58 | + /** | |
| 59 | + * Returns the number of entries (distinct keys) in this dictionary. | |
| 60 | + * | |
| 61 | + * @return the number of keys in this dictionary. | |
| 62 | + */ | |
| 63 | + abstract public int size(); | |
| 64 | + | |
| 65 | + /** | |
| 66 | + * Tests if this dictionary maps no keys to value. The general contract | |
| 67 | + * for the <tt>isEmpty</tt> method is that the result is true if and only | |
| 68 | + * if this dictionary contains no entries. | |
| 69 | + * | |
| 70 | + * @return <code>true</code> if this dictionary maps no keys to values; | |
| 71 | + * <code>false</code> otherwise. | |
| 72 | + */ | |
| 73 | + abstract public boolean isEmpty(); | |
| 74 | + | |
| 75 | + /** | |
| 76 | + * Returns an enumeration of the keys in this dictionary. The general | |
| 77 | + * contract for the keys method is that an <tt>Enumeration</tt> object | |
| 78 | + * is returned that will generate all the keys for which this dictionary | |
| 79 | + * contains entries. | |
| 80 | + * | |
| 81 | + * @return an enumeration of the keys in this dictionary. | |
| 82 | + * @see java.util.Dictionary#elements() | |
| 83 | + * @see java.util.Enumeration | |
| 84 | + */ | |
| 85 | + abstract public Enumeration<K> keys(); | |
| 86 | + | |
| 87 | + /** | |
| 88 | + * Returns an enumeration of the values in this dictionary. The general | |
| 89 | + * contract for the <tt>elements</tt> method is that an | |
| 90 | + * <tt>Enumeration</tt> is returned that will generate all the elements | |
| 91 | + * contained in entries in this dictionary. | |
| 92 | + * | |
| 93 | + * @return an enumeration of the values in this dictionary. | |
| 94 | + * @see java.util.Dictionary#keys() | |
| 95 | + * @see java.util.Enumeration | |
| 96 | + */ | |
| 97 | + abstract public Enumeration<V> elements(); | |
| 98 | + | |
| 99 | + /** | |
| 100 | + * Returns the value to which the key is mapped in this dictionary. | |
| 101 | + * The general contract for the <tt>isEmpty</tt> method is that if this | |
| 102 | + * dictionary contains an entry for the specified key, the associated | |
| 103 | + * value is returned; otherwise, <tt>null</tt> is returned. | |
| 104 | + * | |
| 105 | + * @return the value to which the key is mapped in this dictionary; | |
| 106 | + * @param key a key in this dictionary. | |
| 107 | + * <code>null</code> if the key is not mapped to any value in | |
| 108 | + * this dictionary. | |
| 109 | + * @exception NullPointerException if the <tt>key</tt> is <tt>null</tt>. | |
| 110 | + * @see java.util.Dictionary#put(java.lang.Object, java.lang.Object) | |
| 111 | + */ | |
| 112 | + abstract public V get(Object key); | |
| 113 | + | |
| 114 | + /** | |
| 115 | + * Maps the specified <code>key</code> to the specified | |
| 116 | + * <code>value</code> in this dictionary. Neither the key nor the | |
| 117 | + * value can be <code>null</code>. | |
| 118 | + * <p> | |
| 119 | + * If this dictionary already contains an entry for the specified | |
| 120 | + * <tt>key</tt>, the value already in this dictionary for that | |
| 121 | + * <tt>key</tt> is returned, after modifying the entry to contain the | |
| 122 | + * new element. <p>If this dictionary does not already have an entry | |
| 123 | + * for the specified <tt>key</tt>, an entry is created for the | |
| 124 | + * specified <tt>key</tt> and <tt>value</tt>, and <tt>null</tt> is | |
| 125 | + * returned. | |
| 126 | + * <p> | |
| 127 | + * The <code>value</code> can be retrieved by calling the | |
| 128 | + * <code>get</code> method with a <code>key</code> that is equal to | |
| 129 | + * the original <code>key</code>. | |
| 130 | + * | |
| 131 | + * @param key the hashtable key. | |
| 132 | + * @param value the value. | |
| 133 | + * @return the previous value to which the <code>key</code> was mapped | |
| 134 | + * in this dictionary, or <code>null</code> if the key did not | |
| 135 | + * have a previous mapping. | |
| 136 | + * @exception NullPointerException if the <code>key</code> or | |
| 137 | + * <code>value</code> is <code>null</code>. | |
| 138 | + * @see java.lang.Object#equals(java.lang.Object) | |
| 139 | + * @see java.util.Dictionary#get(java.lang.Object) | |
| 140 | + */ | |
| 141 | + abstract public V put(K key, V value); | |
| 142 | + | |
| 143 | + /** | |
| 144 | + * Removes the <code>key</code> (and its corresponding | |
| 145 | + * <code>value</code>) from this dictionary. This method does nothing | |
| 146 | + * if the <code>key</code> is not in this dictionary. | |
| 147 | + * | |
| 148 | + * @param key the key that needs to be removed. | |
| 149 | + * @return the value to which the <code>key</code> had been mapped in this | |
| 150 | + * dictionary, or <code>null</code> if the key did not have a | |
| 151 | + * mapping. | |
| 152 | + * @exception NullPointerException if <tt>key</tt> is <tt>null</tt>. | |
| 153 | + */ | |
| 154 | + abstract public V remove(Object key); | |
| 155 | +} | |