| /* Dictionary.java -- an abstract (and essentially worthless) |
| class which is Hashtable's superclass |
| Copyright (C) 1998, 2001, 2002 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath 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 for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package java.util; |
| |
| /** |
| * A Dictionary maps keys to values; <i>how</i> it does that is |
| * implementation-specific. |
| * |
| * This is an abstract class which has really gone by the wayside. |
| * People at Javasoft are probably embarrassed by it. At this point, |
| * it might as well be an interface rather than a class, but it remains |
| * this poor, laughable skeleton for the sake of backwards compatibility. |
| * At any rate, this was what came before the {@link Map} interface |
| * in the Collections framework. |
| * |
| * @author Jon Zeppieri |
| * @author Eric Blake (ebb9@email.byu.edu) |
| * @see Map |
| * @see Hashtable |
| * @since 1.0 |
| * @status updated to 1.4 |
| */ |
| public abstract class Dictionary |
| { |
| // WARNING: Dictionary is a CORE class in the bootstrap cycle. See the |
| // comments in vm/reference/java/lang/Runtime for implications of this fact. |
| |
| /** |
| * Sole constructor (often called implicitly). |
| */ |
| public Dictionary() |
| { |
| } |
| |
| /** |
| * Returns an Enumeration of the values in this Dictionary. |
| * |
| * @return an Enumeration of the values |
| * @see #keys() |
| */ |
| public abstract Enumeration elements(); |
| |
| /** |
| * Returns the value associated with the supplied key, or null |
| * if no such value exists. Since Dictionaries are not allowed null keys |
| * or elements, a null result always means the key is not present. |
| * |
| * @param key the key to use to fetch the value |
| * @return the mapped value |
| * @throws NullPointerException if key is null |
| * @see #put(Object, Object) |
| */ |
| public abstract Object get(Object key); |
| |
| /** |
| * Returns true when there are no elements in this Dictionary. |
| * |
| * @return <code>size() == 0</code> |
| */ |
| public abstract boolean isEmpty(); |
| |
| /** |
| * Returns an Enumeration of the keys in this Dictionary |
| * |
| * @return an Enumeration of the keys |
| * @see #elements() |
| */ |
| public abstract Enumeration keys(); |
| |
| /** |
| * Inserts a new value into this Dictionary, located by the |
| * supplied key. Dictionary does not support null keys or values, so |
| * a null return can safely be interpreted as adding a new key. |
| * |
| * @param key the key which locates the value |
| * @param value the value to put into the Dictionary |
| * @return the previous value of the key, or null if there was none |
| * @throws NullPointerException if key or value is null |
| * @see #get(Object) |
| */ |
| public abstract Object put(Object key, Object value); |
| |
| /** |
| * Removes from the Dictionary the value located by the given key. A null |
| * return safely means that the key was not mapped in the Dictionary. |
| * |
| * @param key the key used to locate the value to be removed |
| * @return the value associated with the removed key |
| * @throws NullPointerException if key is null |
| */ |
| public abstract Object remove(Object key); |
| |
| /** |
| * Returns the number of values currently in this Dictionary. |
| * |
| * @return the number of keys in the Dictionary |
| */ |
| public abstract int size(); |
| } // class Dictionary |