libjava/classpath/javax/management/openmbean/TabularType.java

   1 /* TabularType.java -- Type descriptor for TabularData instances.
   2    Copyright (C) 2006, 2007 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38 package javax.management.openmbean;
  39
  40 import java.util.Arrays;
  41 import java.util.Collections;
  42 import java.util.Iterator;
  43 import java.util.List;
  44
  45 /**
  46  * The open type descriptor for instances of the
  47  * {@link TabularData} class.
  48  *
  49  * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
  50  * @since 1.5
  51  */
  52 public class TabularType
  53   extends OpenType<TabularData>
  54 {
  55
  56   /**
  57    * Compatible with JDK 1.5
  58    */
  59   private static final long serialVersionUID = 6554071860220659261L;
  60
  61   /**
  62    * The composite type used by the rows of the table.
  63    */
  64   private CompositeType rowType;
  65
  66   /**
  67    * The list of index names, which form the columns of the table.
  68    * They are retained in the order given by the user, and is
  69    * unmodifiable.
  70    */
  71   private List<String> indexNames;
  72
  73   /**
  74    * The hash code of this instance.
  75    */
  76   private transient Integer hashCode;
  77
  78   /**
  79    * The <code>toString()</code> result of this instance.
  80    */
  81   private transient String string;
  82
  83   /**
  84    * <p>
  85    * Constructs a new {@link TabularType} instance for the given
  86    * type name, description, row type and index names.  All parameters
  87    * (including the individual elements of the array of index names)
  88    * must be non-null and those that are of type {@link java.lang.String}
  89    * must be non-empty.  The array of index names must also be non-empty.
  90    * </p>
  91    * <p>
  92    * The result of <code>TabularData.class.getName()</code> is adopted
  93    * as the class name (see {@link OpenType}).  The ordering of the array
  94    * elements is relevant in determining the indicies of the values in the
  95    * table, and thus in the use of the
  96    * {@link TabularData#get(java.lang.Object[])} and
  97    * {@link TabularData#remove(java.lang.Object[])} methods of the
  98    * {@link TabularData} class.
  99    * </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 }