jdk/src/java.base/share/classes/java/util/Dictionary.java
changeset 25859 3317bb8137f4
parent 24865 09b1d992ca72
child 32108 aa5490a167ee
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/java.base/share/classes/java/util/Dictionary.java	Sun Aug 17 15:54:13 2014 +0100
@@ -0,0 +1,155 @@
+/*
+ * Copyright (c) 1995, 2004, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package java.util;
+
+/**
+ * The <code>Dictionary</code> class is the abstract parent of any
+ * class, such as <code>Hashtable</code>, which maps keys to values.
+ * Every key and every value is an object. In any one <tt>Dictionary</tt>
+ * object, every key is associated with at most one value. Given a
+ * <tt>Dictionary</tt> and a key, the associated element can be looked up.
+ * Any non-<code>null</code> object can be used as a key and as a value.
+ * <p>
+ * As a rule, the <code>equals</code> method should be used by
+ * implementations of this class to decide if two keys are the same.
+ * <p>
+ * <strong>NOTE: This class is obsolete.  New implementations should
+ * implement the Map interface, rather than extending this class.</strong>
+ *
+ * @author  unascribed
+ * @see     java.util.Map
+ * @see     java.lang.Object#equals(java.lang.Object)
+ * @see     java.lang.Object#hashCode()
+ * @see     java.util.Hashtable
+ * @since   1.0
+ */
+public abstract
+class Dictionary<K,V> {
+    /**
+     * Sole constructor.  (For invocation by subclass constructors, typically
+     * implicit.)
+     */
+    public Dictionary() {
+    }
+
+    /**
+     * Returns the number of entries (distinct keys) in this dictionary.
+     *
+     * @return  the number of keys in this dictionary.
+     */
+    abstract public int size();
+
+    /**
+     * Tests if this dictionary maps no keys to value. The general contract
+     * for the <tt>isEmpty</tt> method is that the result is true if and only
+     * if this dictionary contains no entries.
+     *
+     * @return  <code>true</code> if this dictionary maps no keys to values;
+     *          <code>false</code> otherwise.
+     */
+    abstract public boolean isEmpty();
+
+    /**
+     * Returns an enumeration of the keys in this dictionary. The general
+     * contract for the keys method is that an <tt>Enumeration</tt> object
+     * is returned that will generate all the keys for which this dictionary
+     * contains entries.
+     *
+     * @return  an enumeration of the keys in this dictionary.
+     * @see     java.util.Dictionary#elements()
+     * @see     java.util.Enumeration
+     */
+    abstract public Enumeration<K> keys();
+
+    /**
+     * Returns an enumeration of the values in this dictionary. The general
+     * contract for the <tt>elements</tt> method is that an
+     * <tt>Enumeration</tt> is returned that will generate all the elements
+     * contained in entries in this dictionary.
+     *
+     * @return  an enumeration of the values in this dictionary.
+     * @see     java.util.Dictionary#keys()
+     * @see     java.util.Enumeration
+     */
+    abstract public Enumeration<V> elements();
+
+    /**
+     * Returns the value to which the key is mapped in this dictionary.
+     * The general contract for the <tt>isEmpty</tt> method is that if this
+     * dictionary contains an entry for the specified key, the associated
+     * value is returned; otherwise, <tt>null</tt> is returned.
+     *
+     * @return  the value to which the key is mapped in this dictionary;
+     * @param   key   a key in this dictionary.
+     *          <code>null</code> if the key is not mapped to any value in
+     *          this dictionary.
+     * @exception NullPointerException if the <tt>key</tt> is <tt>null</tt>.
+     * @see     java.util.Dictionary#put(java.lang.Object, java.lang.Object)
+     */
+    abstract public V get(Object key);
+
+    /**
+     * Maps the specified <code>key</code> to the specified
+     * <code>value</code> in this dictionary. Neither the key nor the
+     * value can be <code>null</code>.
+     * <p>
+     * If this dictionary already contains an entry for the specified
+     * <tt>key</tt>, the value already in this dictionary for that
+     * <tt>key</tt> is returned, after modifying the entry to contain the
+     *  new element. <p>If this dictionary does not already have an entry
+     *  for the specified <tt>key</tt>, an entry is created for the
+     *  specified <tt>key</tt> and <tt>value</tt>, and <tt>null</tt> is
+     *  returned.
+     * <p>
+     * The <code>value</code> can be retrieved by calling the
+     * <code>get</code> method with a <code>key</code> that is equal to
+     * the original <code>key</code>.
+     *
+     * @param      key     the hashtable key.
+     * @param      value   the value.
+     * @return     the previous value to which the <code>key</code> was mapped
+     *             in this dictionary, or <code>null</code> if the key did not
+     *             have a previous mapping.
+     * @exception  NullPointerException  if the <code>key</code> or
+     *               <code>value</code> is <code>null</code>.
+     * @see        java.lang.Object#equals(java.lang.Object)
+     * @see        java.util.Dictionary#get(java.lang.Object)
+     */
+    abstract public V put(K key, V value);
+
+    /**
+     * Removes the <code>key</code> (and its corresponding
+     * <code>value</code>) from this dictionary. This method does nothing
+     * if the <code>key</code> is not in this dictionary.
+     *
+     * @param   key   the key that needs to be removed.
+     * @return  the value to which the <code>key</code> had been mapped in this
+     *          dictionary, or <code>null</code> if the key did not have a
+     *          mapping.
+     * @exception NullPointerException if <tt>key</tt> is <tt>null</tt>.
+     */
+    abstract public V remove(Object key);
+}