1 /*
2 * Copyright (c) 1996, 2013, 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</code> is an abstract base class for formatting locale-sensitive
45 * information such as dates, messages, and numbers.
46 *
47 * <p>
48 * <code>Format</code> defines the programming interface for formatting
49 * locale-sensitive objects into <code>String</code>s (the
50 * <code>format</code> method) and for parsing <code>String</code>s back
51 * into objects (the <code>parseObject</code> method).
52 *
53 * <p>
54 * Generally, a format's <code>parseObject</code> method must be able to parse
55 * any string formatted by its <code>format</code> method. However, there may
56 * be exceptional cases where this is not possible. For example, a
57 * <code>format</code> method might create two adjacent integer numbers with
58 * no separator in between, and in this case the <code>parseObject</code> could
59 * not tell which digits belong to which number.
60 *
61 * <h3>Subclassing</h3>
62 *
63 * <p>
64 * The Java Platform provides three specialized subclasses of <code>Format</code>--
65 * <code>DateFormat</code>, <code>MessageFormat</code>, and
66 * <code>NumberFormat</code>--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)</code>
72 * <li> <code>formatToCharacterIterator(Object obj)</code>
73 * <li> <code>parseObject(String source, ParsePosition pos)</code>
74 * </ol>
75 * These general methods allow polymorphic parsing and formatting of objects
76 * and are used, for example, by <code>MessageFormat</code>.
77 * Subclasses often also provide additional <code>format</code> methods for
78 * specific input types as well as <code>parse</code> methods for specific
79 * result types. Any <code>parse</code> method that does not take a
80 * <code>ParsePosition</code> argument should throw <code>ParseException</code>
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</code> for getting a useful format object appropriate
88 * for the current locale
89 * <li>
90 * <code>getInstance(Locale)</code> 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</code> methods for more specialized control. For
95 * example, the <code>NumberFormat</code> class provides
96 * <code>getPercentInstance</code> and <code>getCurrencyInstance</code>
97 * methods for getting specialized number formatters.
98 *
99 * <p>
100 * Subclasses of <code>Format</code> that allow programmers to create objects
101 * for locales (with <code>getInstance(Locale)</code> 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</code> and its
116 * friends in {@link DateFormat}.
117 *
118 * <h4><a id="synchronization">Synchronization</a></h4>
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 private static final long serialVersionUID = -299282585814624189L;
137
138 /**
139 * Sole constructor. (For invocation by subclass constructors, typically
140 * implicit.)
141 */
142 protected Format() {
143 }
144
145 /**
146 * Formats an object to produce a string. This is equivalent to
147 * <blockquote>
148 * {@link #format(Object, StringBuffer, FieldPosition) format}<code>(obj,
149 * new StringBuffer(), new FieldPosition(0)).toString();</code>
150 * </blockquote>
151 *
152 * @param obj The object to format
153 * @return Formatted string.
154 * @exception IllegalArgumentException if the Format cannot format the given
155 * object
156 */
157 public final String format (Object obj) {
158 return format(obj, new StringBuffer(), new FieldPosition(0)).toString();
159 }
160
161 /**
162 * Formats an object and appends the resulting text to a given string
163 * buffer.
164 * If the <code>pos</code> argument identifies a field used by the format,
165 * then its indices are set to the beginning and end of the first such
166 * field encountered.
167 *
168 * @param obj The object to format
169 * @param toAppendTo where the text is to be appended
170 * @param pos A <code>FieldPosition</code> identifying a field
171 * in the formatted text
172 * @return the string buffer passed in as <code>toAppendTo</code>,
173 * with formatted text appended
174 * @exception NullPointerException if <code>toAppendTo</code> or
175 * <code>pos</code> is null
176 * @exception IllegalArgumentException if the Format cannot format the given
177 * object
178 */
179 public abstract StringBuffer format(Object obj,
180 StringBuffer toAppendTo,
181 FieldPosition pos);
182
183 /**
184 * Formats an Object producing an <code>AttributedCharacterIterator</code>.
185 * You can use the returned <code>AttributedCharacterIterator</code>
186 * to build the resulting String, as well as to determine information
187 * about the resulting String.
188 * <p>
189 * Each attribute key of the AttributedCharacterIterator will be of type
190 * <code>Field</code>. It is up to each <code>Format</code> implementation
191 * to define what the legal values are for each attribute in the
192 * <code>AttributedCharacterIterator</code>, but typically the attribute
193 * key is also used as the attribute value.
194 * <p>The default implementation creates an
195 * <code>AttributedCharacterIterator</code> with no attributes. Subclasses
196 * that support fields should override this and create an
197 * <code>AttributedCharacterIterator</code> with meaningful attributes.
198 *
199 * @exception NullPointerException if obj is null.
200 * @exception IllegalArgumentException when the Format cannot format the
201 * given object.
202 * @param obj The object to format
203 * @return AttributedCharacterIterator describing the formatted value.
204 * @since 1.4
205 */
206 public AttributedCharacterIterator formatToCharacterIterator(Object obj) {
207 return createAttributedCharacterIterator(format(obj));
208 }
209
210 /**
211 * Parses text from a string to produce an object.
212 * <p>
213 * The method attempts to parse text starting at the index given by
214 * <code>pos</code>.
215 * If parsing succeeds, then the index of <code>pos</code> is updated
216 * to the index after the last character used (parsing does not necessarily
217 * use all characters up to the end of the string), and the parsed
218 * object is returned. The updated <code>pos</code> can be used to
219 * indicate the starting point for the next call to this method.
220 * If an error occurs, then the index of <code>pos</code> is not
221 * changed, the error index of <code>pos</code> is set to the index of
222 * the character where the error occurred, and null is returned.
223 *
224 * @param source A <code>String</code>, part of which should be parsed.
225 * @param pos A <code>ParsePosition</code> object with index and error
226 * index information as described above.
227 * @return An <code>Object</code> parsed from the string. In case of
228 * error, returns null.
229 * @throws NullPointerException if {@code source} or {@code pos} is null.
230 */
231 public abstract Object parseObject (String source, ParsePosition pos);
232
233 /**
234 * Parses text from the beginning of the given string to produce an object.
235 * The method may not use the entire text of the given string.
236 *
237 * @param source A <code>String</code> whose beginning should be parsed.
238 * @return An <code>Object</code> parsed from the string.
239 * @exception ParseException if the beginning of the specified string
240 * cannot be parsed.
241 * @throws NullPointerException if {@code source} is null.
242 */
243 public Object parseObject(String source) throws ParseException {
244 ParsePosition pos = new ParsePosition(0);
245 Object result = parseObject(source, pos);
246 if (pos.index == 0) {
247 throw new ParseException("Format.parseObject(String) failed",
248 pos.errorIndex);
249 }
250 return result;
251 }
252
253 /**
254 * Creates and returns a copy of this object.
255 *
256 * @return a clone of this instance.
257 */
258 public Object clone() {
259 try {
260 return super.clone();
261 } catch (CloneNotSupportedException e) {
262 // will never happen
263 throw new InternalError(e);
264 }
265 }
266
267 //
268 // Convenience methods for creating AttributedCharacterIterators from
269 // different parameters.
270 //
271
272 /**
273 * Creates an <code>AttributedCharacterIterator</code> for the String
274 * <code>s</code>.
275 *
276 * @param s String to create AttributedCharacterIterator from
277 * @return AttributedCharacterIterator wrapping s
278 */
279 AttributedCharacterIterator createAttributedCharacterIterator(String s) {
280 AttributedString as = new AttributedString(s);
281
282 return as.getIterator();
283 }
284
285 /**
286 * Creates an <code>AttributedCharacterIterator</code> containing the
287 * concatenated contents of the passed in
288 * <code>AttributedCharacterIterator</code>s.
289 *
290 * @param iterators AttributedCharacterIterators used to create resulting
291 * AttributedCharacterIterators
292 * @return AttributedCharacterIterator wrapping passed in
293 * AttributedCharacterIterators
294 */
295 AttributedCharacterIterator createAttributedCharacterIterator(
296 AttributedCharacterIterator[] iterators) {
297 AttributedString as = new AttributedString(iterators);
298
299 return as.getIterator();
300 }
301
302 /**
303 * Returns an AttributedCharacterIterator with the String
304 * <code>string</code> and additional key/value pair <code>key</code>,
305 * <code>value</code>.
306 *
307 * @param string String to create AttributedCharacterIterator from
308 * @param key Key for AttributedCharacterIterator
309 * @param value Value associated with key in AttributedCharacterIterator
310 * @return AttributedCharacterIterator wrapping args
311 */
312 AttributedCharacterIterator createAttributedCharacterIterator(
313 String string, AttributedCharacterIterator.Attribute key,
314 Object value) {
315 AttributedString as = new AttributedString(string);
316
317 as.addAttribute(key, value);
318 return as.getIterator();
319 }
320
321 /**
322 * Creates an AttributedCharacterIterator with the contents of
323 * <code>iterator</code> and the additional attribute <code>key</code>
324 * <code>value</code>.
325 *
326 * @param iterator Initial AttributedCharacterIterator to add arg to
327 * @param key Key for AttributedCharacterIterator
328 * @param value Value associated with key in AttributedCharacterIterator
329 * @return AttributedCharacterIterator wrapping args
330 */
331 AttributedCharacterIterator createAttributedCharacterIterator(
332 AttributedCharacterIterator iterator,
333 AttributedCharacterIterator.Attribute key, Object value) {
334 AttributedString as = new AttributedString(iterator);
335
336 as.addAttribute(key, value);
337 return as.getIterator();
338 }
339
340
341 /**
342 * Defines constants that are used as attribute keys in the
343 * <code>AttributedCharacterIterator</code> returned
344 * from <code>Format.formatToCharacterIterator</code> and as
345 * field identifiers in <code>FieldPosition</code>.
346 *
347 * @since 1.4
348 */
349 public static class Field extends AttributedCharacterIterator.Attribute {
350
351 // Proclaim serial compatibility with 1.4 FCS
352 private static final long serialVersionUID = 276966692217360283L;
353
354 /**
355 * Creates a Field with the specified name.
356 *
357 * @param name Name of the attribute
358 */
359 protected Field(String name) {
360 super(name);
361 }
362 }
363
364
365 /**
366 * FieldDelegate is notified by the various <code>Format</code>
367 * implementations as they are formatting the Objects. This allows for
368 * storage of the individual sections of the formatted String for
369 * later use, such as in a <code>FieldPosition</code> or for an
370 * <code>AttributedCharacterIterator</code>.
371 * <p>
372 * Delegates should NOT assume that the <code>Format</code> will notify
373 * the delegate of fields in any particular order.
374 *
375 * @see FieldPosition#getFieldDelegate
376 * @see CharacterIteratorFieldDelegate
377 */
378 interface FieldDelegate {
379 /**
380 * Notified when a particular region of the String is formatted. This
381 * method will be invoked if there is no corresponding integer field id
382 * matching <code>attr</code>.
383 *
384 * @param attr Identifies the field matched
385 * @param value Value associated with the field
386 * @param start Beginning location of the field, will be >= 0
387 * @param end End of the field, will be >= start and <= buffer.length()
388 * @param buffer Contains current formatted value, receiver should
389 * NOT modify it.
390 */
391 public void formatted(Format.Field attr, Object value, int start,
392 int end, StringBuffer buffer);
393
394 /**
395 * Notified when a particular region of the String is formatted.
396 *
397 * @param fieldID Identifies the field by integer
398 * @param attr Identifies the field matched
399 * @param value Value associated with the field
400 * @param start Beginning location of the field, will be >= 0
401 * @param end End of the field, will be >= start and <= buffer.length()
402 * @param buffer Contains current formatted value, receiver should
403 * NOT modify it.
404 */
405 public void formatted(int fieldID, Format.Field attr, Object value,
406 int start, int end, StringBuffer buffer);
407 }
408 }