001/* TabularType.java -- Type descriptor for TabularData instances. 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.Arrays; 041import java.util.Collections; 042import java.util.Iterator; 043import 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 */ 052public 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}