1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<!--NewPage--> 3<HTML> 4<HEAD> 5<!-- Generated by javadoc (build 1.5.0) on Thu May 15 17:17:33 EDT 2008 --> 6<TITLE> 7Conversion (Oracle - Berkeley DB Java API) 8</TITLE> 9 10<META NAME="keywords" CONTENT="com.sleepycat.persist.evolve.Conversion interface"> 11 12<LINK REL ="stylesheet" TYPE="text/css" HREF="../../../../style.css" TITLE="Style"> 13 14<SCRIPT type="text/javascript"> 15function windowTitle() 16{ 17 parent.document.title="Conversion (Oracle - Berkeley DB Java API)"; 18} 19</SCRIPT> 20<NOSCRIPT> 21</NOSCRIPT> 22 23</HEAD> 24 25<BODY BGCOLOR="white" onload="windowTitle();"> 26 27 28<!-- ========= START OF TOP NAVBAR ======= --> 29<A NAME="navbar_top"><!-- --></A> 30<A HREF="#skip-navbar_top" title="Skip navigation links"></A> 31<TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY=""> 32<TR> 33<TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> 34<A NAME="navbar_top_firstrow"><!-- --></A> 35<TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY=""> 36 <TR ALIGN="center" VALIGN="top"> 37 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A> </TD> 38 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A> </TD> 39 <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> 40 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="class-use/Conversion.html"><FONT CLASS="NavBarFont1"><B>Use</B></FONT></A> </TD> 41 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD> 42 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> 43 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD> 44 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD> 45 </TR> 46</TABLE> 47</TD> 48<TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM> 49<b>Berkeley DB</b><br><font size="-1"> version 4.7.25</font></EM> 50</TD> 51</TR> 52 53<TR> 54<TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> 55 PREV CLASS 56 <A HREF="../../../../com/sleepycat/persist/evolve/Converter.html" title="class in com.sleepycat.persist.evolve"><B>NEXT CLASS</B></A></FONT></TD> 57<TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> 58 <A HREF="../../../../index.html?com/sleepycat/persist/evolve/Conversion.html" target="_top"><B>FRAMES</B></A> 59 <A HREF="Conversion.html" target="_top"><B>NO FRAMES</B></A> 60 <SCRIPT type="text/javascript"> 61 <!-- 62 if(window==top) { 63 document.writeln('<A HREF="../../../../allclasses-noframe.html"><B>All Classes</B></A>'); 64 } 65 //--> 66</SCRIPT> 67<NOSCRIPT> 68 <A HREF="../../../../allclasses-noframe.html"><B>All Classes</B></A> 69</NOSCRIPT> 70 71 72</FONT></TD> 73</TR> 74<TR> 75<TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> 76 SUMMARY: NESTED | FIELD | CONSTR | <A HREF="#method_summary">METHOD</A></FONT></TD> 77<TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> 78DETAIL: FIELD | CONSTR | <A HREF="#method_detail">METHOD</A></FONT></TD> 79</TR> 80</TABLE> 81<A NAME="skip-navbar_top"></A> 82<!-- ========= END OF TOP NAVBAR ========= --> 83 84<HR> 85<!-- ======== START OF CLASS DATA ======== --> 86<H2> 87<FONT SIZE="-1"> 88com.sleepycat.persist.evolve</FONT> 89<BR> 90Interface Conversion</H2> 91<DL> 92<DT><B>All Superinterfaces:</B> <DD><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/io/Serializable.html" title="class or interface in java.io">Serializable</A></DD> 93</DL> 94<HR> 95<DL> 96<DT><PRE>public interface <B>Conversion</B><DT>extends <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/io/Serializable.html" title="class or interface in java.io">Serializable</A></DL> 97</PRE> 98 99<P> 100Converts an old version of an object value to conform to the current class 101 or field definition. 102 103 <p>The <code>Conversion</code> interface is implemented by the user. A 104 <code>Conversion</code> instance is passed to the <A HREF="../../../../com/sleepycat/persist/evolve/Converter.html#Converter(java.lang.String, int, java.lang.String, com.sleepycat.persist.evolve.Conversion)"><CODE>Converter.Converter(java.lang.String, int, java.lang.String, com.sleepycat.persist.evolve.Conversion)</CODE></A> 105 constructor.</p> 106 107 <p>The <code>Conversion</code> interface extends <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/io/Serializable.html" title="class or interface in java.io"><CODE>Serializable</CODE></A> and the 108 <code>Conversion</code> instance is serialized for storage using standard Java 109 serialization. Normally, the <code>Conversion</code> class should only have 110 transient fields that are initialized in the <A HREF="../../../../com/sleepycat/persist/evolve/Conversion.html#initialize(com.sleepycat.persist.model.EntityModel)"><CODE>initialize(com.sleepycat.persist.model.EntityModel)</CODE></A> method. 111 While non-transient fields are allowed, care must be taken to only include 112 fields that are serializable and will not pull in large amounts of data.</p> 113 114 <p>When a class conversion is specified, two special considerations 115 apply:</p> 116 <ol> 117 <li>A class conversion is only applied when to instances of that class. The 118 conversion will not be applied when the class when it appears as a 119 superclass of the instance's class. In this case, a conversion for the 120 instance's class must also be specified.</li> 121 <li>Although field renaming (as well as all other changes) is handled by the 122 conversion method, a field Renamer is still needed when a secondary key 123 field is renamed and field Deleter is still needed when a secondary key 124 field is deleted. This is necessary for evolution of the metadata; 125 specifically, if the key name changes the database must be renamed and if 126 the key field is deleted the secondary database must be deleted.</li> 127 </ol> 128 129 <p>The <code>Conversion</code> class must implement the standard equals method. 130 See <A HREF="../../../../com/sleepycat/persist/evolve/Conversion.html#equals(java.lang.Object)"><CODE>equals(java.lang.Object)</CODE></A> for more information.</p> 131 132 <p>Conversions of simple types are generally simple. For example, a <code>String</code> field that contains only integer values can be easily converted to 133 an <code>int</code> field:</p> 134 <pre class="code"> 135 // The old class. Version 0 is implied. 136 // 137 @Persistent 138 class Address { 139 String zipCode; 140 ... 141 } 142 143 // The new class. A new version number must be assigned. 144 // 145 @Persistent(version=1) 146 class Address { 147 int zipCode; 148 ... 149 } 150 151 // The conversion class. 152 // 153 class MyConversion1 implements Conversion { 154 155 public void initialize(EntityModel model) { 156 // No initialization needed. 157 } 158 159 public Object convert(Object fromValue) { 160 return Integer.valueOf((String) fromValue); 161 } 162 163 <code>@Override</code> 164 public boolean equals(Object o) { 165 return o instanceof MyConversion1; 166 } 167 } 168 169 // Create a field converter mutation. 170 // 171 Converter converter = new Converter(Address.class.getName(), 0, 172 "zipCode", new MyConversion1()); 173 174 // Configure the converter as described <A HREF="../../../../com/sleepycat/persist/evolve/Mutations.html" title="class in com.sleepycat.persist.evolve"><CODE>here</CODE></A>.</pre> 175 176 <p>A conversion may perform arbitrary transformations on an object. For 177 example, a conversion may transform a single String address field into an 178 Address object containing four fields for street, city, state and zip 179 code.</p> 180 <pre class="code"> 181 // The old class. Version 0 is implied. 182 // 183 @Entity 184 class Person { 185 String address; 186 ... 187 } 188 189 // The new class. A new version number must be assigned. 190 // 191 @Entity(version=1) 192 class Person { 193 Address address; 194 ... 195 } 196 197 // The new address class. 198 // 199 @Persistent 200 class Address { 201 String street; 202 String city; 203 String state; 204 int zipCode; 205 ... 206 } 207 208 class MyConversion2 implements Conversion { 209 private transient RawType addressType; 210 211 public void initialize(EntityModel model) { 212 addressType = model.getRawType(Address.class.getName()); 213 } 214 215 public Object convert(Object fromValue) { 216 217 // Parse the old address and populate the new address fields 218 // 219 String oldAddress = (String) fromValue; 220 Map<String,Object> addressValues = new HashMap<String,Object>(); 221 addressValues.put("street", parseStreet(oldAddress)); 222 addressValues.put("city", parseCity(oldAddress)); 223 addressValues.put("state", parseState(oldAddress)); 224 addressValues.put("zipCode", parseZipCode(oldAddress)); 225 226 // Return new raw Address object 227 // 228 return new RawObject(addressType, addressValues, null); 229 } 230 231 <code>@Override</code> 232 public boolean equals(Object o) { 233 return o instanceof MyConversion2; 234 } 235 236 private String parseStreet(String oldAddress) { ... } 237 private String parseCity(String oldAddress) { ... } 238 private String parseState(String oldAddress) { ... } 239 private Integer parseZipCode(String oldAddress) { ... } 240 } 241 242 // Create a field converter mutation. 243 // 244 Converter converter = new Converter(Person.class.getName(), 0, 245 "address", new MyConversion2()); 246 247 // Configure the converter as described <A HREF="../../../../com/sleepycat/persist/evolve/Mutations.html" title="class in com.sleepycat.persist.evolve"><CODE>here</CODE></A>.</pre> 248 249 <p>Note that when a conversion returns a <A HREF="../../../../com/sleepycat/persist/raw/RawObject.html" title="class in com.sleepycat.persist.raw"><CODE>RawObject</CODE></A>, it must return 250 it with a <A HREF="../../../../com/sleepycat/persist/raw/RawType.html" title="interface in com.sleepycat.persist.raw"><CODE>RawType</CODE></A> that is current as defined by the current class 251 definitions. The proper types can be obtained from the <A HREF="../../../../com/sleepycat/persist/model/EntityModel.html" title="class in com.sleepycat.persist.model"><CODE>EntityModel</CODE></A> 252 in the conversion's <A HREF="../../../../com/sleepycat/persist/evolve/Conversion.html#initialize(com.sleepycat.persist.model.EntityModel)"><CODE>initialize</CODE></A> method.</p> 253 254 <p>A variation on the example above is where several fields in a class 255 (street, city, state and zipCode) are converted to a single field (address). 256 In this case a class converter rather than a field converter is used.</p> 257 258 <pre class="code"> 259 // The old class. Version 0 is implied. 260 // 261 @Entity 262 class Person { 263 String street; 264 String city; 265 String state; 266 int zipCode; 267 ... 268 } 269 270 // The new class. A new version number must be assigned. 271 // 272 @Entity(version=1) 273 class Person { 274 Address address; 275 ... 276 } 277 278 // The new address class. 279 // 280 @Persistent 281 class Address { 282 String street; 283 String city; 284 String state; 285 int zipCode; 286 ... 287 } 288 289 class MyConversion3 implements Conversion { 290 private transient RawType newPersonType; 291 private transient RawType addressType; 292 293 public void initialize(EntityModel model) { 294 newPersonType = model.getRawType(Person.class.getName()); 295 addressType = model.getRawType(Address.class.getName()); 296 } 297 298 public Object convert(Object fromValue) { 299 300 // Get field value maps for old and new objects. 301 // 302 RawObject person = (RawObject) fromValue; 303 Map<String,Object> personValues = person.getValues(); 304 Map<String,Object> addressValues = new HashMap<String,Object>(); 305 RawObject address = new RawObject(addressType, addressValues, null); 306 307 // Remove the old address fields and insert the new one. 308 // 309 addressValues.put("street", personValues.remove("street")); 310 addressValues.put("city", personValues.remove("city")); 311 addressValues.put("state", personValues.remove("state")); 312 addressValues.put("zipCode", personValues.remove("zipCode")); 313 personValues.put("address", address); 314 315 return new RawObject(newPersonType, personValues, person.getSuper()); 316 } 317 318 <code>@Override</code> 319 public boolean equals(Object o) { 320 return o instanceof MyConversion3; 321 } 322 } 323 324 // Create a class converter mutation. 325 // 326 Converter converter = new Converter(Person.class.getName(), 0, 327 new MyConversion3()); 328 329 // Configure the converter as described <A HREF="../../../../com/sleepycat/persist/evolve/Mutations.html" title="class in com.sleepycat.persist.evolve"><CODE>here</CODE></A>.</pre> 330 331 332 <p>A conversion can also handle changes to class hierarchies. For example, 333 if a "name" field originally declared in class A is moved to its superclass 334 B, a conversion can move the field value accordingly:</p> 335 336 <pre class="code"> 337 // The old classes. Version 0 is implied. 338 // 339 @Persistent 340 class A extends B { 341 String name; 342 ... 343 } 344 @Persistent 345 abstract class B { 346 ... 347 } 348 349 // The new classes. A new version number must be assigned. 350 // 351 @Persistent(version=1) 352 class A extends B { 353 ... 354 } 355 @Persistent(version=1) 356 abstract class B { 357 String name; 358 ... 359 } 360 361 class MyConversion4 implements Conversion { 362 private transient RawType newAType; 363 private transient RawType newBType; 364 365 public void initialize(EntityModel model) { 366 newAType = model.getRawType(A.class.getName()); 367 newBType = model.getRawType(B.class.getName()); 368 } 369 370 public Object convert(Object fromValue) { 371 RawObject oldA = (RawObject) fromValue; 372 RawObject oldB = oldA.getSuper(); 373 Map<String,Object> aValues = oldA.getValues(); 374 Map<String,Object> bValues = oldB.getValues(); 375 bValues.put("name", aValues.remove("name")); 376 RawObject newB = new RawObject(newBType, bValues, oldB.getSuper()); 377 RawObject newA = new RawObject(newAType, aValues, newB); 378 return newA; 379 } 380 381 <code>@Override</code> 382 public boolean equals(Object o) { 383 return o instanceof MyConversion4; 384 } 385 } 386 387 // Create a class converter mutation. 388 // 389 Converter converter = new Converter(A.class.getName(), 0, 390 new MyConversion4()); 391 392 // Configure the converter as described <A HREF="../../../../com/sleepycat/persist/evolve/Mutations.html" title="class in com.sleepycat.persist.evolve"><CODE>here</CODE></A>.</pre> 393 394 <p>A conversion may return an instance of a different class entirely, as 395 long as it conforms to current class definitions and is the type expected 396 in the given context (a subtype of the old type, or a type compatible with 397 the new field type). For example, a field that is used to discriminate 398 between two types of objects could be removed and replaced by two new 399 subclasses:</p> <pre class="code"> 400 // The old class. Version 0 is implied. 401 // 402 @Persistent 403 class Pet { 404 boolean isCatNotDog; 405 ... 406 } 407 408 // The new classes. A new version number must be assigned to the Pet class. 409 // 410 @Persistent(version=1) 411 class Pet { 412 ... 413 } 414 @Persistent 415 class Cat extends Pet { 416 ... 417 } 418 @Persistent 419 class Dog extends Pet { 420 ... 421 } 422 423 class MyConversion5 implements Conversion { 424 private transient RawType newPetType; 425 private transient RawType dogType; 426 private transient RawType catType; 427 428 public void initialize(EntityModel model) { 429 newPetType = model.getRawType(Pet.class.getName()); 430 dogType = model.getRawType(Dog.class.getName()); 431 catType = model.getRawType(Cat.class.getName()); 432 } 433 434 public Object convert(Object fromValue) { 435 RawObject pet = (RawObject) fromValue; 436 Map<String,Object> petValues = pet.getValues(); 437 Boolean isCat = (Boolean) petValues.remove("isCatNotDog"); 438 RawObject newPet = new RawObject(newPetType, petValues, 439 pet.getSuper()); 440 RawType newSubType = isCat ? catType : dogType; 441 return new RawObject(newSubType, Collections.emptyMap(), newPet); 442 } 443 444 <code>@Override</code> 445 public boolean equals(Object o) { 446 return o instanceof MyConversion5; 447 } 448 } 449 450 // Create a class converter mutation. 451 // 452 Converter converter = new Converter(Pet.class.getName(), 0, 453 new MyConversion5()); 454 455 // Configure the converter as described <A HREF="../../../../com/sleepycat/persist/evolve/Mutations.html" title="class in com.sleepycat.persist.evolve"><CODE>here</CODE></A>.</pre> 456 457 <p>The primary limitation of a conversion is that it may access at most a 458 single entity instance at one time. Conversions involving multiple entities 459 at once may be made by performing a <a 460 href="package-summary.html#storeConversion">store conversion</a>.</p> 461<P> 462 463<P> 464<DL> 465<DT><B>See Also:</B><DD><A HREF="../../../../com/sleepycat/persist/evolve/package-summary.html"><CODE>Class Evolution</CODE></A></DL> 466<HR> 467 468<P> 469 470<!-- ========== METHOD SUMMARY =========== --> 471 472<A NAME="method_summary"><!-- --></A> 473<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""> 474<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"> 475<TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2"> 476<B>Method Summary</B></FONT></TH> 477</TR> 478<TR BGCOLOR="white" CLASS="TableRowColor"> 479<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> 480<CODE> <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html" title="class or interface in java.lang">Object</A></CODE></FONT></TD> 481<TD><CODE><B><A HREF="../../../../com/sleepycat/persist/evolve/Conversion.html#convert(java.lang.Object)">convert</A></B>(<A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html" title="class or interface in java.lang">Object</A> fromValue)</CODE> 482 483<BR> 484 Converts an old version of an object value to conform to the current 485 class or field definition.</TD> 486</TR> 487<TR BGCOLOR="white" CLASS="TableRowColor"> 488<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> 489<CODE> boolean</CODE></FONT></TD> 490<TD><CODE><B><A HREF="../../../../com/sleepycat/persist/evolve/Conversion.html#equals(java.lang.Object)">equals</A></B>(<A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html" title="class or interface in java.lang">Object</A> other)</CODE> 491 492<BR> 493 The standard <code>equals</code> method that must be implemented by 494 conversion class.</TD> 495</TR> 496<TR BGCOLOR="white" CLASS="TableRowColor"> 497<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> 498<CODE> void</CODE></FONT></TD> 499<TD><CODE><B><A HREF="../../../../com/sleepycat/persist/evolve/Conversion.html#initialize(com.sleepycat.persist.model.EntityModel)">initialize</A></B>(<A HREF="../../../../com/sleepycat/persist/model/EntityModel.html" title="class in com.sleepycat.persist.model">EntityModel</A> model)</CODE> 500 501<BR> 502 Initializes the conversion, allowing it to obtain raw type information 503 from the entity model.</TD> 504</TR> 505</TABLE> 506 507<P> 508 509<!-- ============ METHOD DETAIL ========== --> 510 511<A NAME="method_detail"><!-- --></A> 512<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""> 513<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"> 514<TH ALIGN="left" COLSPAN="1"><FONT SIZE="+2"> 515<B>Method Detail</B></FONT></TH> 516</TR> 517</TABLE> 518 519<A NAME="initialize(com.sleepycat.persist.model.EntityModel)"><!-- --></A><H3> 520initialize</H3> 521<PRE> 522void <B>initialize</B>(<A HREF="../../../../com/sleepycat/persist/model/EntityModel.html" title="class in com.sleepycat.persist.model">EntityModel</A> model)</PRE> 523<DL> 524<DD>Initializes the conversion, allowing it to obtain raw type information 525 from the entity model. 526<P> 527<DD><DL> 528</DL> 529</DD> 530<DD><DL> 531</DL> 532</DD> 533</DL> 534<HR> 535 536<A NAME="convert(java.lang.Object)"><!-- --></A><H3> 537convert</H3> 538<PRE> 539<A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html" title="class or interface in java.lang">Object</A> <B>convert</B>(<A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html" title="class or interface in java.lang">Object</A> fromValue)</PRE> 540<DL> 541<DD>Converts an old version of an object value to conform to the current 542 class or field definition. 543 544 <p>If a <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/RuntimeException.html" title="class or interface in java.lang"><CODE>RuntimeException</CODE></A> is thrown by this method, it will be 545 thrown to the original caller. Similarly, a <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/IllegalArgumentException.html" title="class or interface in java.lang"><CODE>IllegalArgumentException</CODE></A> will be thrown to the original caller if the 546 object returned by this method does not conform to current class 547 definitions.</p> 548 549 <p>The class of the input and output object may be one of the simple 550 types or <A HREF="../../../../com/sleepycat/persist/raw/RawObject.html" title="class in com.sleepycat.persist.raw"><CODE>RawObject</CODE></A>. For primitive types, the primitive wrapper 551 class is used.</p> 552<P> 553<DD><DL> 554</DL> 555</DD> 556<DD><DL> 557<DT><B>Parameters:</B><DD><CODE>fromValue</CODE> - the object value being converted. The type of this 558 value is defined by the old class version that is being converted. 559<DT><B>Returns:</B><DD>the converted object. The type of this value must conform to 560 a current class definition. If this is a class conversion, it must 561 be the current version of the class. If this is a field conversion, it 562 must be of a type compatible with the current declared type of the 563 field.</DL> 564</DD> 565</DL> 566<HR> 567 568<A NAME="equals(java.lang.Object)"><!-- --></A><H3> 569equals</H3> 570<PRE> 571boolean <B>equals</B>(<A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html" title="class or interface in java.lang">Object</A> other)</PRE> 572<DL> 573<DD>The standard <code>equals</code> method that must be implemented by 574 conversion class. 575 576 <p>When mutations are specified when opening a store, the specified and 577 previously stored mutations are compared for equality. If they are 578 equal, there is no need to replace the existing mutations in the stored 579 catalog. To accurately determine equality, the conversion class must 580 implement the <code>equals</code> method.</p> 581 582 <p>If the <code>equals</code> method is not explicitly implemented by the 583 conversion class or a superclass other than <code>Object</code>, <code>IllegalArgumentException</code> will be thrown when the store is opened.</p> 584 585 <p>Normally whenever <code>equals</code> is implemented the <code>hashCode</code> 586 method should also be implemented to support hash sets and maps. 587 However, hash sets and maps containing <code>Conversion</code> objects 588 are not used by the DPL and therefore the DPL does not require 589 <code>hashCode</code> to be implemented.</p> 590<P> 591<DD><DL> 592<DT><B>Overrides:</B><DD><CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html#equals(java.lang.Object)" title="class or interface in java.lang">equals</A></CODE> in class <CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html" title="class or interface in java.lang">Object</A></CODE></DL> 593</DD> 594<DD><DL> 595</DL> 596</DD> 597</DL> 598<!-- ========= END OF CLASS DATA ========= --> 599<HR> 600 601 602<!-- ======= START OF BOTTOM NAVBAR ====== --> 603<A NAME="navbar_bottom"><!-- --></A> 604<A HREF="#skip-navbar_bottom" title="Skip navigation links"></A> 605<TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY=""> 606<TR> 607<TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> 608<A NAME="navbar_bottom_firstrow"><!-- --></A> 609<TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY=""> 610 <TR ALIGN="center" VALIGN="top"> 611 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A> </TD> 612 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A> </TD> 613 <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> 614 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="class-use/Conversion.html"><FONT CLASS="NavBarFont1"><B>Use</B></FONT></A> </TD> 615 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD> 616 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> 617 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD> 618 <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD> 619 </TR> 620</TABLE> 621</TD> 622<TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM> 623<b>Berkeley DB</b><br><font size="-1"> version 4.7.25</font></EM> 624</TD> 625</TR> 626 627<TR> 628<TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> 629 PREV CLASS 630 <A HREF="../../../../com/sleepycat/persist/evolve/Converter.html" title="class in com.sleepycat.persist.evolve"><B>NEXT CLASS</B></A></FONT></TD> 631<TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> 632 <A HREF="../../../../index.html?com/sleepycat/persist/evolve/Conversion.html" target="_top"><B>FRAMES</B></A> 633 <A HREF="Conversion.html" target="_top"><B>NO FRAMES</B></A> 634 <SCRIPT type="text/javascript"> 635 <!-- 636 if(window==top) { 637 document.writeln('<A HREF="../../../../allclasses-noframe.html"><B>All Classes</B></A>'); 638 } 639 //--> 640</SCRIPT> 641<NOSCRIPT> 642 <A HREF="../../../../allclasses-noframe.html"><B>All Classes</B></A> 643</NOSCRIPT> 644 645 646</FONT></TD> 647</TR> 648<TR> 649<TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> 650 SUMMARY: NESTED | FIELD | CONSTR | <A HREF="#method_summary">METHOD</A></FONT></TD> 651<TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> 652DETAIL: FIELD | CONSTR | <A HREF="#method_detail">METHOD</A></FONT></TD> 653</TR> 654</TABLE> 655<A NAME="skip-navbar_bottom"></A> 656<!-- ======== END OF BOTTOM NAVBAR ======= --> 657 658<HR> 659<font size=1>Copyright (c) 1996,2008 Oracle. 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