/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package java.util;
/**
* <strong>Note: Do not use this class since it is obsolete. Please use the
* {@link Map} interface for new implementations.</strong>
* <p>
* Dictionary is an abstract class which is the superclass of all classes that
* associate keys with values, such as {@code Hashtable}.
*
* @see Hashtable
* @since 1.0
*/
public abstract class Dictionary<K, V> {
/**
* Constructs a new instance of this class.
*/
public Dictionary() {
}
/**
* Returns an enumeration on the elements of this dictionary.
*
* @return an enumeration of the values of this dictionary.
* @see #keys
* @see #size
* @see Enumeration
*/
public abstract Enumeration<V> elements();
/**
* Returns the value which is associated with {@code key}.
*
* @param key
* the key of the value returned.
* @return the value associated with {@code key}, or {@code null} if the
* specified key does not exist.
* @see #put
*/
public abstract V get(Object key);
/**
* Returns true if this dictionary has no key/value pairs.
*
* @return {@code true} if this dictionary has no key/value pairs,
* {@code false} otherwise.
* @see #size
*/
public abstract boolean isEmpty();
/**
* Returns an enumeration on the keys of this dictionary.
*
* @return an enumeration of the keys of this dictionary.
* @see #elements
* @see #size
* @see Enumeration
*/
public abstract Enumeration<K> keys();
/**
* Associate {@code key} with {@code value} in this dictionary. If {@code
* key} exists in the dictionary before this call, the old value in the
* dictionary is replaced by {@code value}.
*
* @param key
* the key to add.
* @param value
* the value to add.
* @return the old value previously associated with {@code key} or {@code
* null} if {@code key} is new to the dictionary.
* @see #elements
* @see #get
* @see #keys
*/
public abstract V put(K key, V value);
/**
* Removes the key/value pair with the specified {@code key} from this
* dictionary.
*
* @param key
* the key to remove.
* @return the associated value before the deletion or {@code null} if
* {@code key} was not known to this dictionary.
* @see #get
* @see #put
*/
public abstract V remove(Object key);
/**
* Returns the number of key/value pairs in this dictionary.
*
* @return the number of key/value pairs in this dictionary.
* @see #elements
* @see #keys
*/
public abstract int size();
}