1 /* 2 * Copyright (c) 1996, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 /* 27 * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved 28 * (C) Copyright IBM Corp. 1996 - 1998 - All Rights Reserved 29 * 30 * The original version of this source code and documentation is copyrighted 31 * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These 32 * materials are provided under terms of a License Agreement between Taligent 33 * and Sun. This technology is protected by multiple US and International 34 * patents. This notice and attribution to Taligent may not be removed. 35 * Taligent is a registered trademark of Taligent, Inc. 36 * 37 */ 38 39 package java.text; 40 41 import java.io.Serializable; 42 43 /** 44 * {@code Format} is an abstract base class for formatting locale-sensitive 45 * information such as dates, messages, and numbers. 46 * 47 * <p> 48 * {@code Format} defines the programming interface for formatting 49 * locale-sensitive objects into {@code String}s (the 50 * {@code format} method) and for parsing {@code String}s back 51 * into objects (the {@code parseObject} method). 52 * 53 * <p> 54 * Generally, a format's {@code parseObject} method must be able to parse 55 * any string formatted by its {@code format} method. However, there may 56 * be exceptional cases where this is not possible. For example, a 57 * {@code format} method might create two adjacent integer numbers with 58 * no separator in between, and in this case the {@code parseObject} could 59 * not tell which digits belong to which number. 60 * 61 * <h2>Subclassing</h2> 62 * 63 * <p> 64 * The Java Platform provides three specialized subclasses of {@code Format}-- 65 * {@code DateFormat}, {@code MessageFormat}, and 66 * {@code NumberFormat}--for formatting dates, messages, and numbers, 67 * respectively. 68 * <p> 69 * Concrete subclasses must implement three methods: 70 * <ol> 71 * <li> {@code format(Object obj, StringBuffer toAppendTo, FieldPosition pos)} 72 * <li> {@code formatToCharacterIterator(Object obj)} 73 * <li> {@code parseObject(String source, ParsePosition pos)} 74 * </ol> 75 * These general methods allow polymorphic parsing and formatting of objects 76 * and are used, for example, by {@code MessageFormat}. 77 * Subclasses often also provide additional {@code format} methods for 78 * specific input types as well as {@code parse} methods for specific 79 * result types. Any {@code parse} method that does not take a 80 * {@code ParsePosition} argument should throw {@code ParseException} 81 * when no text in the required format is at the beginning of the input text. 82 * 83 * <p> 84 * Most subclasses will also implement the following factory methods: 85 * <ol> 86 * <li> 87 * {@code getInstance} for getting a useful format object appropriate 88 * for the current locale 89 * <li> 90 * {@code getInstance(Locale)} for getting a useful format 91 * object appropriate for the specified locale 92 * </ol> 93 * In addition, some subclasses may also implement other 94 * {@code getXxxxInstance} methods for more specialized control. For 95 * example, the {@code NumberFormat} class provides 96 * {@code getPercentInstance} and {@code getCurrencyInstance} 97 * methods for getting specialized number formatters. 98 * 99 * <p> 100 * Subclasses of {@code Format} that allow programmers to create objects 101 * for locales (with {@code getInstance(Locale)} for example) 102 * must also implement the following class method: 103 * <blockquote> 104 * <pre> 105 * public static Locale[] getAvailableLocales() 106 * </pre> 107 * </blockquote> 108 * 109 * <p> 110 * And finally subclasses may define a set of constants to identify the various 111 * fields in the formatted output. These constants are used to create a FieldPosition 112 * object which identifies what information is contained in the field and its 113 * position in the formatted result. These constants should be named 114 * <code><em>item</em>_FIELD</code> where <code><em>item</em></code> identifies 115 * the field. For examples of these constants, see {@code ERA_FIELD} and its 116 * friends in {@link DateFormat}. 117 * 118 * <h3><a id="synchronization">Synchronization</a></h3> 119 * 120 * <p> 121 * Formats are generally not synchronized. 122 * It is recommended to create separate format instances for each thread. 123 * If multiple threads access a format concurrently, it must be synchronized 124 * externally. 125 * 126 * @see java.text.ParsePosition 127 * @see java.text.FieldPosition 128 * @see java.text.NumberFormat 129 * @see java.text.DateFormat 130 * @see java.text.MessageFormat 131 * @author Mark Davis 132 * @since 1.1 133 */ 134 public abstract class Format implements Serializable, Cloneable { 135 136 @java.io.Serial 137 private static final long serialVersionUID = -299282585814624189L; 138 139 /** 140 * Sole constructor. (For invocation by subclass constructors, typically 141 * implicit.) 142 */ Format()143 protected Format() { 144 } 145 146 /** 147 * Formats an object to produce a string. This is equivalent to 148 * <blockquote> 149 * {@link #format(Object, StringBuffer, FieldPosition) format}<code>(obj, 150 * new StringBuffer(), new FieldPosition(0)).toString();</code> 151 * </blockquote> 152 * 153 * @param obj The object to format 154 * @return Formatted string. 155 * @throws IllegalArgumentException if the Format cannot format the given 156 * object 157 */ format(Object obj)158 public final String format (Object obj) { 159 return format(obj, new StringBuffer(), new FieldPosition(0)).toString(); 160 } 161 162 /** 163 * Formats an object and appends the resulting text to a given string 164 * buffer. 165 * If the {@code pos} argument identifies a field used by the format, 166 * then its indices are set to the beginning and end of the first such 167 * field encountered. 168 * 169 * @param obj The object to format 170 * @param toAppendTo where the text is to be appended 171 * @param pos A {@code FieldPosition} identifying a field 172 * in the formatted text 173 * @return the string buffer passed in as {@code toAppendTo}, 174 * with formatted text appended 175 * @throws NullPointerException if {@code toAppendTo} or 176 * {@code pos} is null 177 * @throws IllegalArgumentException if the Format cannot format the given 178 * object 179 */ format(Object obj, StringBuffer toAppendTo, FieldPosition pos)180 public abstract StringBuffer format(Object obj, 181 StringBuffer toAppendTo, 182 FieldPosition pos); 183 184 /** 185 * Formats an Object producing an {@code AttributedCharacterIterator}. 186 * You can use the returned {@code AttributedCharacterIterator} 187 * to build the resulting String, as well as to determine information 188 * about the resulting String. 189 * <p> 190 * Each attribute key of the AttributedCharacterIterator will be of type 191 * {@code Field}. It is up to each {@code Format} implementation 192 * to define what the legal values are for each attribute in the 193 * {@code AttributedCharacterIterator}, but typically the attribute 194 * key is also used as the attribute value. 195 * <p>The default implementation creates an 196 * {@code AttributedCharacterIterator} with no attributes. Subclasses 197 * that support fields should override this and create an 198 * {@code AttributedCharacterIterator} with meaningful attributes. 199 * 200 * @throws NullPointerException if obj is null. 201 * @throws IllegalArgumentException when the Format cannot format the 202 * given object. 203 * @param obj The object to format 204 * @return AttributedCharacterIterator describing the formatted value. 205 * @since 1.4 206 */ formatToCharacterIterator(Object obj)207 public AttributedCharacterIterator formatToCharacterIterator(Object obj) { 208 return createAttributedCharacterIterator(format(obj)); 209 } 210 211 /** 212 * Parses text from a string to produce an object. 213 * <p> 214 * The method attempts to parse text starting at the index given by 215 * {@code pos}. 216 * If parsing succeeds, then the index of {@code pos} is updated 217 * to the index after the last character used (parsing does not necessarily 218 * use all characters up to the end of the string), and the parsed 219 * object is returned. The updated {@code pos} can be used to 220 * indicate the starting point for the next call to this method. 221 * If an error occurs, then the index of {@code pos} is not 222 * changed, the error index of {@code pos} is set to the index of 223 * the character where the error occurred, and null is returned. 224 * 225 * @param source A {@code String}, part of which should be parsed. 226 * @param pos A {@code ParsePosition} object with index and error 227 * index information as described above. 228 * @return An {@code Object} parsed from the string. In case of 229 * error, returns null. 230 * @throws NullPointerException if {@code source} or {@code pos} is null. 231 */ parseObject(String source, ParsePosition pos)232 public abstract Object parseObject (String source, ParsePosition pos); 233 234 /** 235 * Parses text from the beginning of the given string to produce an object. 236 * The method may not use the entire text of the given string. 237 * 238 * @param source A {@code String} whose beginning should be parsed. 239 * @return An {@code Object} parsed from the string. 240 * @throws ParseException if the beginning of the specified string 241 * cannot be parsed. 242 * @throws NullPointerException if {@code source} is null. 243 */ parseObject(String source)244 public Object parseObject(String source) throws ParseException { 245 ParsePosition pos = new ParsePosition(0); 246 Object result = parseObject(source, pos); 247 if (pos.index == 0) { 248 throw new ParseException("Format.parseObject(String) failed", 249 pos.errorIndex); 250 } 251 return result; 252 } 253 254 /** 255 * Creates and returns a copy of this object. 256 * 257 * @return a clone of this instance. 258 */ clone()259 public Object clone() { 260 try { 261 return super.clone(); 262 } catch (CloneNotSupportedException e) { 263 // will never happen 264 throw new InternalError(e); 265 } 266 } 267 268 // 269 // Convenience methods for creating AttributedCharacterIterators from 270 // different parameters. 271 // 272 273 /** 274 * Creates an {@code AttributedCharacterIterator} for the String 275 * {@code s}. 276 * 277 * @param s String to create AttributedCharacterIterator from 278 * @return AttributedCharacterIterator wrapping s 279 */ createAttributedCharacterIterator(String s)280 AttributedCharacterIterator createAttributedCharacterIterator(String s) { 281 AttributedString as = new AttributedString(s); 282 283 return as.getIterator(); 284 } 285 286 /** 287 * Creates an {@code AttributedCharacterIterator} containing the 288 * concatenated contents of the passed in 289 * {@code AttributedCharacterIterator}s. 290 * 291 * @param iterators AttributedCharacterIterators used to create resulting 292 * AttributedCharacterIterators 293 * @return AttributedCharacterIterator wrapping passed in 294 * AttributedCharacterIterators 295 */ createAttributedCharacterIterator( AttributedCharacterIterator[] iterators)296 AttributedCharacterIterator createAttributedCharacterIterator( 297 AttributedCharacterIterator[] iterators) { 298 AttributedString as = new AttributedString(iterators); 299 300 return as.getIterator(); 301 } 302 303 /** 304 * Returns an AttributedCharacterIterator with the String 305 * {@code string} and additional key/value pair {@code key}, 306 * {@code value}. 307 * 308 * @param string String to create AttributedCharacterIterator from 309 * @param key Key for AttributedCharacterIterator 310 * @param value Value associated with key in AttributedCharacterIterator 311 * @return AttributedCharacterIterator wrapping args 312 */ createAttributedCharacterIterator( String string, AttributedCharacterIterator.Attribute key, Object value)313 AttributedCharacterIterator createAttributedCharacterIterator( 314 String string, AttributedCharacterIterator.Attribute key, 315 Object value) { 316 AttributedString as = new AttributedString(string); 317 318 as.addAttribute(key, value); 319 return as.getIterator(); 320 } 321 322 /** 323 * Creates an AttributedCharacterIterator with the contents of 324 * {@code iterator} and the additional attribute {@code key} 325 * {@code value}. 326 * 327 * @param iterator Initial AttributedCharacterIterator to add arg to 328 * @param key Key for AttributedCharacterIterator 329 * @param value Value associated with key in AttributedCharacterIterator 330 * @return AttributedCharacterIterator wrapping args 331 */ createAttributedCharacterIterator( AttributedCharacterIterator iterator, AttributedCharacterIterator.Attribute key, Object value)332 AttributedCharacterIterator createAttributedCharacterIterator( 333 AttributedCharacterIterator iterator, 334 AttributedCharacterIterator.Attribute key, Object value) { 335 AttributedString as = new AttributedString(iterator); 336 337 as.addAttribute(key, value); 338 return as.getIterator(); 339 } 340 341 342 /** 343 * Defines constants that are used as attribute keys in the 344 * {@code AttributedCharacterIterator} returned 345 * from {@code Format.formatToCharacterIterator} and as 346 * field identifiers in {@code FieldPosition}. 347 * 348 * @since 1.4 349 */ 350 public static class Field extends AttributedCharacterIterator.Attribute { 351 352 // Proclaim serial compatibility with 1.4 FCS 353 @java.io.Serial 354 private static final long serialVersionUID = 276966692217360283L; 355 356 /** 357 * Creates a Field with the specified name. 358 * 359 * @param name Name of the attribute 360 */ Field(String name)361 protected Field(String name) { 362 super(name); 363 } 364 } 365 366 367 /** 368 * FieldDelegate is notified by the various {@code Format} 369 * implementations as they are formatting the Objects. This allows for 370 * storage of the individual sections of the formatted String for 371 * later use, such as in a {@code FieldPosition} or for an 372 * {@code AttributedCharacterIterator}. 373 * <p> 374 * Delegates should NOT assume that the {@code Format} will notify 375 * the delegate of fields in any particular order. 376 * 377 * @see FieldPosition#getFieldDelegate 378 * @see CharacterIteratorFieldDelegate 379 */ 380 interface FieldDelegate { 381 /** 382 * Notified when a particular region of the String is formatted. This 383 * method will be invoked if there is no corresponding integer field id 384 * matching {@code attr}. 385 * 386 * @param attr Identifies the field matched 387 * @param value Value associated with the field 388 * @param start Beginning location of the field, will be >= 0 389 * @param end End of the field, will be >= start and <= buffer.length() 390 * @param buffer Contains current formatted value, receiver should 391 * NOT modify it. 392 */ formatted(Format.Field attr, Object value, int start, int end, StringBuffer buffer)393 public void formatted(Format.Field attr, Object value, int start, 394 int end, StringBuffer buffer); 395 396 /** 397 * Notified when a particular region of the String is formatted. 398 * 399 * @param fieldID Identifies the field by integer 400 * @param attr Identifies the field matched 401 * @param value Value associated with the field 402 * @param start Beginning location of the field, will be >= 0 403 * @param end End of the field, will be >= start and <= buffer.length() 404 * @param buffer Contains current formatted value, receiver should 405 * NOT modify it. 406 */ formatted(int fieldID, Format.Field attr, Object value, int start, int end, StringBuffer buffer)407 public void formatted(int fieldID, Format.Field attr, Object value, 408 int start, int end, StringBuffer buffer); 409 } 410 } 411