- 001
/* - 002
* @(#)Dictionary.java 1.24 05/11/17 - 003 *
- 004 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
- 005 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
- 006
*/ - 007
- 008package java.util;
- 009
- 010/**
- 011 * The <code>Dictionary</code> class is the abstract parent of any
- 012 * class, such as <code>Hashtable</code>, which maps keys to values.
- 013 * Every key and every value is an object. In any one <tt>Dictionary</tt>
- 014 * object, every key is associated with at most one value. Given a
- 015 * <tt>Dictionary</tt> and a key, the associated element can be looked up.
- 016 * Any non-<code>null</code> object can be used as a key and as a value.
- 017 * <p>
- 018 * As a rule, the <code>equals</code> method should be used by
- 019 * implementations of this class to decide if two keys are the same.
- 020 * <p>
- 021 * <strong>NOTE: This class is obsolete. New implementations should
- 022 * implement the Map interface, rather than extending this class.</strong>
- 023 *
- 024 * @author unascribed
- 025 * @version 1.24, 11/17/05
- 026 * @see java.util.Map
- 027 * @see java.lang.Object#equals(java.lang.Object)
- 028 * @see java.lang.Object#hashCode()
- 029 * @see java.util.Hashtable
- 030 * @since JDK1.0
- 031 */
- 032public abstract
- 033class Dictionary<K,V> {
- 034 /**
- 035 * Sole constructor. (For invocation by subclass constructors, typically
- 036 * implicit.)
- 037 */
- 038 public Dictionary() {
- 039 }
- 040
- 041 /**
- 042 * Returns the number of entries (distinct keys) in this dictionary.
- 043 *
- 044 * @return the number of keys in this dictionary.
- 045 */
- 046 abstract public int size();
- 047
- 048 /**
- 049 * Tests if this dictionary maps no keys to value. The general contract
- 050 * for the <tt>isEmpty</tt> method is that the result is true if and only
- 051 * if this dictionary contains no entries.
- 052 *
- 053 * @return <code>true</code> if this dictionary maps no keys to values;
- 054 * <code>false</code> otherwise.
- 055 */
- 056 abstract public boolean isEmpty();
- 057
- 058 /**
- 059 * Returns an enumeration of the keys in this dictionary. The general
- 060 * contract for the keys method is that an <tt>Enumeration</tt> object
- 061 * is returned that will generate all the keys for which this dictionary
- 062 * contains entries.
- 063 *
- 064 * @return an enumeration of the keys in this dictionary.
- 065 * @see java.util.Dictionary#elements()
- 066 * @see java.util.Enumeration
- 067 */
- 068 abstract public Enumeration<K> keys();
- 069
- 070 /**
- 071 * Returns an enumeration of the values in this dictionary. The general
- 072 * contract for the <tt>elements</tt> method is that an
- 073 * <tt>Enumeration</tt> is returned that will generate all the elements
- 074 * contained in entries in this dictionary.
- 075 *
- 076 * @return an enumeration of the values in this dictionary.
- 077 * @see java.util.Dictionary#keys()
- 078 * @see java.util.Enumeration
- 079 */
- 080 abstract public Enumeration<V> elements();
- 081
- 082 /**
- 083 * Returns the value to which the key is mapped in this dictionary.
- 084 * The general contract for the <tt>isEmpty</tt> method is that if this
- 085 * dictionary contains an entry for the specified key, the associated
- 086 * value is returned; otherwise, <tt>null</tt> is returned.
- 087 *
- 088 * @return the value to which the key is mapped in this dictionary;
- 089 * @param key a key in this dictionary.
- 090 * <code>null</code> if the key is not mapped to any value in
- 091 * this dictionary.
- 092 * @exception NullPointerException if the <tt>key</tt> is <tt>null</tt>.
- 093 * @see java.util.Dictionary#put(java.lang.Object, java.lang.Object)
- 094 */
- 095 abstract public V get(Object key);
- 096
- 097 /**
- 098 * Maps the specified <code>key</code> to the specified
- 099 * <code>value</code> in this dictionary. Neither the key nor the
- 100 * value can be <code>null</code>.
- 101 * <p>
- 102 * If this dictionary already contains an entry for the specified
- 103 * <tt>key</tt>, the value already in this dictionary for that
- 104 * <tt>key</tt> is returned, after modifying the entry to contain the
- 105 * new element. <p>If this dictionary does not already have an entry
- 106 * for the specified <tt>key</tt>, an entry is created for the
- 107 * specified <tt>key</tt> and <tt>value</tt>, and <tt>null</tt> is
- 108 * returned.
- 109 * <p>
- 110 * The <code>value</code> can be retrieved by calling the
- 111 * <code>get</code> method with a <code>key</code> that is equal to
- 112 * the original <code>key</code>.
- 113 *
- 114 * @param key the hashtable key.
- 115 * @param value the value.
- 116 * @return the previous value to which the <code>key</code> was mapped
- 117 * in this dictionary, or <code>null</code> if the key did not
- 118 * have a previous mapping.
- 119 * @exception NullPointerException if the <code>key</code> or
- 120 * <code>value</code> is <code>null</code>.
- 121 * @see java.lang.Object#equals(java.lang.Object)
- 122 * @see java.util.Dictionary#get(java.lang.Object)
- 123 */
- 124 abstract public V put(K key, V value);
- 125
- 126 /**
- 127 * Removes the <code>key</code> (and its corresponding
- 128 * <code>value</code>) from this dictionary. This method does nothing
- 129 * if the <code>key</code> is not in this dictionary.
- 130 *
- 131 * @param key the key that needs to be removed.
- 132 * @return the value to which the <code>key</code> had been mapped in this
- 133 * dictionary, or <code>null</code> if the key did not have a
- 134 * mapping.
- 135 * @exception NullPointerException if <tt>key</tt> is <tt>null</tt>.
- 136 */
- 137 abstract public V remove(Object key);
- 138}
