| /* |
| * Copyright (c) 1995, 2020, 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} class is the abstract parent of any |
| * class, such as {@code Hashtable}, which maps keys to values. |
| * Every key and every value is an object. In any one {@code Dictionary} |
| * object, every key is associated with at most one value. Given a |
| * {@code Dictionary} and a key, the associated element can be looked up. |
| * Any non-{@code null} object can be used as a key and as a value. |
| * <p> |
| * As a rule, the {@code equals} 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NOTE: This class is obsolete.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> |
| * |
| * @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. |
| */ |
| public abstract int size(); |
| |
| /** |
| * Tests if this dictionary maps no keys to value. The general contract |
| * for the {@code isEmpty} method is that the result is true if and only |
| * if this dictionary contains no entries. |
| * |
| * @return {@code true} if this dictionary maps no keys to values; |
| * {@code false} otherwise. |
| */ |
| public abstract boolean isEmpty(); |
| |
| /** |
| * Returns an enumeration of the keys in this dictionary. The general |
| * contract for the keys method is that an {@code Enumeration} 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 |
| */ |
| public abstract Enumeration<K> keys(); |
| |
| /** |
| * Returns an enumeration of the values in this dictionary. The general |
| * contract for the {@code elements} method is that an |
| * {@code Enumeration} 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 |
| */ |
| public abstract Enumeration<V> elements(); |
| |
| /** |
| * Returns the value to which the key is mapped in this dictionary. |
| * The general contract for the {@code isEmpty} method is that if this |
| * dictionary contains an entry for the specified key, the associated |
| * value is returned; otherwise, {@code null} is returned. |
| * |
| * @return the value to which the key is mapped in this dictionary; |
| * @param key a key in this dictionary. |
| * {@code null} if the key is not mapped to any value in |
| * this dictionary. |
| * @throws NullPointerException if the {@code key} is {@code null}. |
| * @see java.util.Dictionary#put(java.lang.Object, java.lang.Object) |
| */ |
| public abstract V get(Object key); |
| |
| /** |
| * Maps the specified {@code key} to the specified |
| * {@code value} in this dictionary. Neither the key nor the |
| * value can be {@code null}. |
| * <p> |
| * If this dictionary already contains an entry for the specified |
| * {@code key}, the value already in this dictionary for that |
| * {@code key} is returned, after modifying the entry to contain the |
| * new element. <p>If this dictionary does not already have an entry |
| * for the specified {@code key}, an entry is created for the |
| * specified {@code key} and {@code value}, and {@code null} is |
| * returned. |
| * <p> |
| * The {@code value} can be retrieved by calling the |
| * {@code get} method with a {@code key} that is equal to |
| * the original {@code key}. |
| * |
| * @param key the hashtable key. |
| * @param value the value. |
| * @return the previous value to which the {@code key} was mapped |
| * in this dictionary, or {@code null} if the key did not |
| * have a previous mapping. |
| * @throws NullPointerException if the {@code key} or |
| * {@code value} is {@code null}. |
| * @see java.lang.Object#equals(java.lang.Object) |
| * @see java.util.Dictionary#get(java.lang.Object) |
| */ |
| public abstract V put(K key, V value); |
| |
| /** |
| * Removes the {@code key} (and its corresponding |
| * {@code value}) from this dictionary. This method does nothing |
| * if the {@code key} is not in this dictionary. |
| * |
| * @param key the key that needs to be removed. |
| * @return the value to which the {@code key} had been mapped in this |
| * dictionary, or {@code null} if the key did not have a |
| * mapping. |
| * @throws NullPointerException if {@code key} is {@code null}. |
| */ |
| public abstract V remove(Object key); |
| } |
