001    /* TabularType.java -- Type descriptor for TabularData instances.
002       Copyright (C) 2006, 2007 Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    package javax.management.openmbean;
039    
040    import java.util.Arrays;
041    import java.util.Collections;
042    import java.util.Iterator;
043    import java.util.List;
044    
045    /**
046     * The open type descriptor for instances of the
047     * {@link TabularData} class.
048     * 
049     * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
050     * @since 1.5
051     */
052    public class TabularType
053      extends OpenType<TabularData>
054    {
055    
056      /**
057       * Compatible with JDK 1.5
058       */
059      private static final long serialVersionUID = 6554071860220659261L;
060    
061      /**
062       * The composite type used by the rows of the table.
063       */
064      private CompositeType rowType;
065    
066      /**
067       * The list of index names, which form the columns of the table.
068       * They are retained in the order given by the user, and is
069       * unmodifiable.
070       */
071      private List<String> indexNames;
072    
073      /**
074       * The hash code of this instance.
075       */
076      private transient Integer hashCode;
077    
078      /**
079       * The <code>toString()</code> result of this instance.
080       */
081      private transient String string;
082    
083      /**
084       * <p>
085       * Constructs a new {@link TabularType} instance for the given
086       * type name, description, row type and index names.  All parameters
087       * (including the individual elements of the array of index names)
088       * must be non-null and those that are of type {@link java.lang.String}
089       * must be non-empty.  The array of index names must also be non-empty.
090       * </p>
091       * <p>
092       * The result of <code>TabularData.class.getName()</code> is adopted
093       * as the class name (see {@link OpenType}).  The ordering of the array
094       * elements is relevant in determining the indicies of the values in the
095       * table, and thus in the use of the 
096       * {@link TabularData#get(java.lang.Object[])} and
097       * {@link TabularData#remove(java.lang.Object[])} methods of the
098       * {@link TabularData} class.
099       * </p>
100       *
101       * @param name the name of this tabular type.
102       * @param desc a description of this tabular type.
103       * @param rowType the type of the rows of the table.
104       * @param indexNames the names used to index the rows within the table.
105       * @throws IllegalArgumentException if any validity constraint listed above
106       *                                  is broken.
107       * @throws OpenDataException if an index name does not match a corresponding
108       *                           name in the given row type.
109       */
110      public TabularType(String name, String desc, CompositeType rowType,
111                         String[] indexNames)
112        throws OpenDataException
113      {
114        super(TabularData.class.getName(), name, desc);
115        if (rowType == null)
116          throw new IllegalArgumentException("A null row type was given.");
117        for (int a = 0; a < indexNames.length; ++a)
118          {
119            if (indexNames[a] == null)
120              throw new IllegalArgumentException("Name " + a +
121                                                 " is null.");
122            if (indexNames[a].length() == 0)
123              throw new IllegalArgumentException("Name " + a + 
124                                                 " is the empty string.");
125            if (!(rowType.containsKey(indexNames[a])))
126              throw new OpenDataException("No matching key for " +
127                                          indexNames[a] + " was found in " +
128                                          "the supplied row type.");
129          }
130        this.rowType = rowType;
131        this.indexNames = Collections.unmodifiableList(Arrays.asList(indexNames));
132      }
133    
134      /**
135       * <p>
136       * Compares this tabular data type with another object
137       * for equality.  The objects are judged to be equal if:
138       * </p>
139       * <ul>
140       * <li><code>obj</code> is not null.</li>
141       * <li><code>obj</code> is an instance of
142       * {@link TabularType}.</li>
143       * <li>The type names are equal.</li>
144       * <li>The row types are equal.</li>
145       * <li>The index names are equal and in the same order.</li>
146       * </ul>
147       * 
148       * @param obj the object to compare with.
149       * @return true if the conditions above hold.
150       */
151      public boolean equals(Object obj)
152      {
153        if (!(obj instanceof TabularType))
154          return false;
155        TabularType ttype = (TabularType) obj;
156        return  (ttype.getTypeName().equals(getTypeName())
157                 && (ttype.getRowType().equals(getRowType()))
158                 && (ttype.getIndexNames().equals(getIndexNames())));
159      }
160    
161      /**
162       * Returns an unmodifiable list containing the index names.
163       * The ordering of these names is used to determine the indicies
164       * of the {@link CompositeData} values, and is retained from that
165       * used in the call to this object's constructor.
166       *
167       * @return an unmodifiable list of the index names used by this
168       *         tabular data structure.
169       */
170      public List<String> getIndexNames()
171      {
172        return indexNames;
173      }
174    
175      /**
176       * Returns the type of the rows used by this tabular data structure.
177       *
178       * @return the row type.
179       */
180      public CompositeType getRowType()
181      {
182        return rowType;
183      }
184    
185      /**
186       * <p>
187       * Returns the hash code of the tabular data type.
188       * This is computed as the sum of the hash codes of the
189       * index names together with the hash code of the type
190       * name and row type.  These are the same elements
191       * of the type that are compared as part of the
192       * {@link #equals(java.lang.Object)} method, thus ensuring
193       * that the hashcode is compatible with the equality
194       * test.
195       * </p>
196       * <p>
197       * As instances of this class are immutable, the hash code
198       * is computed just once for each instance and reused
199       * throughout its life.
200       * </p>
201       *
202       * @return the hash code of this instance.
203       */
204      public int hashCode()
205      {
206        if (hashCode == null)
207          {
208            int elementTotal = 0;
209            for (String s : indexNames)
210              elementTotal += s.hashCode();
211            hashCode = Integer.valueOf(elementTotal 
212                                       + getTypeName().hashCode()
213                                       + rowType.hashCode());
214          }
215        return hashCode.intValue();
216      }
217                                   
218      /**
219       * Returns true if the specified object is a member of this
220       * tabular type.  The object is judged to be so if it is
221       * an instance of {@link TabularData} with an equivalent
222       * type, according to the definition of
223       * {@link #equals(java.lang.Object)} for {@link TabularType}.
224       *
225       * @param obj the object to test for membership.
226       * @return true if the object is a member of this type.
227       */
228      public boolean isValue(Object obj)
229      {
230        if (obj instanceof TabularData)
231          {
232            TabularData data = (TabularData) obj;
233            return equals(data.getTabularType());
234          }
235        return false;
236      }
237    
238      /**
239       * <p>
240       * Returns a textual representation of this instance.  This
241       * is constructed using the class name
242       * (<code>javax.management.openmbean.TabularType</code>)
243       * and each element of the instance which is relevant to
244       * the definition of {@link equals(java.lang.Object)} and
245       * {@link hashCode()} (i.e. the type name, the row type
246       * and the index names).
247       * </p>
248       * <p>
249       * As instances of this class are immutable, the return value
250       * is computed just once for each instance and reused
251       * throughout its life.
252       * </p>
253       *
254       * @return a @link{java.lang.String} instance representing
255       *         the instance in textual form.
256       */
257      public String toString()
258      {
259        if (string == null)
260          string = getClass().getName()
261            + "[name=" + getTypeName()
262            + ", rowType=" + rowType
263            + ", indexNames=" + indexNames
264            + "]";
265        return string;
266      }
267    
268    }