001/* CompositeData.java -- A composite data structure.
002   Copyright (C) 2006, 2007 Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038package javax.management.openmbean;
039
040import java.util.Collection;
041
042/**
043 * Provides an interface to a composite data structure,
044 * in order to aid interoperability.  The composite data
045 * structure is represented by mapping field names to
046 * values.
047 *
048 * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
049 * @since 1.5
050 */
051public interface CompositeData
052{
053
054  /**
055   * Returns true if this {@link CompositeData} instance contains
056   * the specified key.  This method always returns false for
057   * an input key equal to <code>null</code> or the empty string.
058   *
059   * @param key the key to find in the structure.
060   * @return true if the key exists.
061   */
062  boolean containsKey(String key);
063
064  /**
065   * Returns true if this {@link CompositeData} instance has
066   * a value equal to that supplied.
067   *
068   * @param value the value to look for.
069   * @return true if the value exists.
070   */
071  boolean containsValue(Object value);
072
073  /**
074   * Compares the specified object with this object for equality.
075   * The object is judged equivalent if it is non-null, and also
076   * an instance of {@link CompositeData} with the same name-value
077   * mappings and types.  The two compared instances may be
078   * equivalent even if they represent different implementations of
079   * {@link CompositeData}.
080   *
081   * @param obj the object to compare for equality.
082   * @return true if <code>obj</code> is equal to <code>this</code>.
083   */
084  boolean equals(Object obj);
085
086  /**
087   * Retrieves the value for the specified key.
088   *
089   * @param key the key whose value should be returned.
090   * @return the matching value.
091   * @throws IllegalArgumentException if the key is <code>null</code>
092   *                                  or the empty string.
093   * @throws InvalidKeyException if the key does not exist.
094   */
095  Object get(String key);
096
097  /**
098   * Returns the appropriate value for each key in the given array,
099   * using the same ordering.
100   *
101   * @param keys the keys whose values should be returned.
102   * @return the matching values.
103   * @throws IllegalArgumentException if one of the keys is
104   *                                  <code>null</code> or the
105   *                                  empty string.
106   * @throws InvalidKeyException if one of the keys does not exist.
107   */
108  Object[] getAll(String[] keys);
109
110  /**
111   * Returns the composite type which corresponds to this instance
112   * of {@link CompositeData}.
113   *
114   * @return the composite type for this instance.
115   */
116  CompositeType getCompositeType();
117
118  /**
119   * Returns the hash code of this instance.  The hash code is
120   * computed as the sum of the hash codes of all the values plus
121   * the hash code of the composite type.  As equality comparisons
122   * take place using this same information, this ensures that
123   * the property, <code>e1.equals(e2)</code> implies
124   * <code>e1.hashCode() == e2.hashCode(), holds for any pair
125   * of instances, <code>e1</code> and <code>e2</code>.
126   *
127   * @return the hash code of this {@link CompositeData}.
128   * @see Object#equals(Object)
129   */
130  int hashCode();
131
132  /**
133   * Returns a textual representation of this instance.  The
134   * exact format is left up to the implementation, but it
135   * should contain the name of the implementing class,
136   * the name of the type and a mapping of the form
137   * <code>key=value</code> for each pair of key and value.
138   *
139   * @return a {@link java.lang.String} representation of the
140   *         object.
141   */
142  String toString();
143
144  /**
145   * Returns a read-only collection of the values associated with
146   * this instance.  The values are sorted using the lexicographic
147   * ordering of the corresponding keys.
148   *
149   * @return the values of this instance.
150   */
151  Collection<?> values();
152
153}