1 /*
2 * Copyright (c) 1996, 2005, 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 * <h4>Subclassing</h4>
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 name="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 */
133 public abstract class Format implements Serializable, Cloneable {
134
135 private static final long serialVersionUID = -299282585814624189L;
136
137 /**
138 * Sole constructor. (For invocation by subclass constructors, typically
139 * implicit.)
140 */
141 protected Format() {
142 }
143
144 /**
145 * Formats an object to produce a string. This is equivalent to
146 * <blockquote>
147 * {@link #format(Object, StringBuffer, FieldPosition) format}<code>(obj,
148 * new StringBuffer(), new FieldPosition(0)).toString();</code>
149 * </blockquote>
150 *
151 * @param obj The object to format
152 * @return Formatted string.
153 * @exception IllegalArgumentException if the Format cannot format the given
154 * object
155 */
156 public final String format (Object obj) {
157 return format(obj, new StringBuffer(), new FieldPosition(0)).toString();
158 }
159
160 /**
161 * Formats an object and appends the resulting text to a given string
162 * buffer.
163 * If the <code>pos</code> argument identifies a field used by the format,
164 * then its indices are set to the beginning and end of the first such
165 * field encountered.
166 *
167 * @param obj The object to format
168 * @param toAppendTo where the text is to be appended
169 * @param pos A <code>FieldPosition</code> identifying a field
170 * in the formatted text
171 * @return the string buffer passed in as <code>toAppendTo</code>,
172 * with formatted text appended
173 * @exception NullPointerException if <code>toAppendTo</code> or
174 * <code>pos</code> is null
175 * @exception IllegalArgumentException if the Format cannot format the given
176 * object
177 */
178 public abstract StringBuffer format(Object obj,
179 StringBuffer toAppendTo,
180 FieldPosition pos);
181
182 /**
183 * Formats an Object producing an <code>AttributedCharacterIterator</code>.
184 * You can use the returned <code>AttributedCharacterIterator</code>
185 * to build the resulting String, as well as to determine information
186 * about the resulting String.
187 * <p>
188 * Each attribute key of the AttributedCharacterIterator will be of type
189 * <code>Field</code>. It is up to each <code>Format</code> implementation
190 * to define what the legal values are for each attribute in the
191 * <code>AttributedCharacterIterator</code>, but typically the attribute
192 * key is also used as the attribute value.
193 * <p>The default implementation creates an
194 * <code>AttributedCharacterIterator</code> with no attributes. Subclasses
195 * that support fields should override this and create an
196 * <code>AttributedCharacterIterator</code> with meaningful attributes.
197 *
198 * @exception NullPointerException if obj is null.
199 * @exception IllegalArgumentException when the Format cannot format the
200 * given object.
201 * @param obj The object to format
202 * @return AttributedCharacterIterator describing the formatted value.
203 * @since 1.4
204 */
205 public AttributedCharacterIterator formatToCharacterIterator(Object obj) {
206 return createAttributedCharacterIterator(format(obj));
207 }
208
209 /**
210 * Parses text from a string to produce an object.
211 * <p>
212 * The method attempts to parse text starting at the index given by
213 * <code>pos</code>.
214 * If parsing succeeds, then the index of <code>pos</code> is updated
215 * to the index after the last character used (parsing does not necessarily
216 * use all characters up to the end of the string), and the parsed
217 * object is returned. The updated <code>pos</code> can be used to
218 * indicate the starting point for the next call to this method.
219 * If an error occurs, then the index of <code>pos</code> is not
220 * changed, the error index of <code>pos</code> is set to the index of
221 * the character where the error occurred, and null is returned.
222 *
223 * @param source A <code>String</code>, part of which should be parsed.
224 * @param pos A <code>ParsePosition</code> object with index and error
225 * index information as described above.
226 * @return An <code>Object</code> parsed from the string. In case of
227 * error, returns null.
228 * @exception NullPointerException if <code>pos</code> is null.
229 */
230 public abstract Object parseObject (String source, ParsePosition pos);
231
232 /**
233 * Parses text from the beginning of the given string to produce an object.
234 * The method may not use the entire text of the given string.
235 *
236 * @param source A <code>String</code> whose beginning should be parsed.
237 * @return An <code>Object</code> parsed from the string.
238 * @exception ParseException if the beginning of the specified string
239 * cannot be parsed.
240 */
241 public Object parseObject(String source) throws ParseException {
242 ParsePosition pos = new ParsePosition(0);
243 Object result = parseObject(source, pos);
244 if (pos.index == 0) {
245 throw new ParseException("Format.parseObject(String) failed",
246 pos.errorIndex);
247 }
248 return result;
249 }
250
251 /**
252 * Creates and returns a copy of this object.
253 *
254 * @return a clone of this instance.
255 */
256 public Object clone() {
257 try {
258 return super.clone();
259 } catch (CloneNotSupportedException e) {
260 // will never happen
261 throw new InternalError(e);
262 }
263 }
264
265 //
266 // Convenience methods for creating AttributedCharacterIterators from
267 // different parameters.
268 //
269
270 /**
271 * Creates an <code>AttributedCharacterIterator</code> for the String
272 * <code>s</code>.
273 *
274 * @param s String to create AttributedCharacterIterator from
275 * @return AttributedCharacterIterator wrapping s
276 */
277 AttributedCharacterIterator createAttributedCharacterIterator(String s) {
278 AttributedString as = new AttributedString(s);
279
280 return as.getIterator();
281 }
282
283 /**
284 * Creates an <code>AttributedCharacterIterator</code> containg the
285 * concatenated contents of the passed in
286 * <code>AttributedCharacterIterator</code>s.
287 *
288 * @param iterators AttributedCharacterIterators used to create resulting
289 * AttributedCharacterIterators
290 * @return AttributedCharacterIterator wrapping passed in
291 * AttributedCharacterIterators
292 */
293 AttributedCharacterIterator createAttributedCharacterIterator(
294 AttributedCharacterIterator[] iterators) {
295 AttributedString as = new AttributedString(iterators);
296
297 return as.getIterator();
298 }
299
300 /**
301 * Returns an AttributedCharacterIterator with the String
302 * <code>string</code> and additional key/value pair <code>key</code>,
303 * <code>value</code>.
304 *
305 * @param string String to create AttributedCharacterIterator from
306 * @param key Key for AttributedCharacterIterator
307 * @param value Value associated with key in AttributedCharacterIterator
308 * @return AttributedCharacterIterator wrapping args
309 */
310 AttributedCharacterIterator createAttributedCharacterIterator(
311 String string, AttributedCharacterIterator.Attribute key,
312 Object value) {
313 AttributedString as = new AttributedString(string);
314
315 as.addAttribute(key, value);
316 return as.getIterator();
317 }
318
319 /**
320 * Creates an AttributedCharacterIterator with the contents of
321 * <code>iterator</code> and the additional attribute <code>key</code>
322 * <code>value</code>.
323 *
324 * @param iterator Initial AttributedCharacterIterator to add arg to
325 * @param key Key for AttributedCharacterIterator
326 * @param value Value associated with key in AttributedCharacterIterator
327 * @return AttributedCharacterIterator wrapping args
328 */
329 AttributedCharacterIterator createAttributedCharacterIterator(
330 AttributedCharacterIterator iterator,
331 AttributedCharacterIterator.Attribute key, Object value) {
332 AttributedString as = new AttributedString(iterator);
333
334 as.addAttribute(key, value);
335 return as.getIterator();
336 }
337
338
339 /**
340 * Defines constants that are used as attribute keys in the
341 * <code>AttributedCharacterIterator</code> returned
342 * from <code>Format.formatToCharacterIterator</code> and as
343 * field identifiers in <code>FieldPosition</code>.
344 *
345 * @since 1.4
346 */
347 public static class Field extends AttributedCharacterIterator.Attribute {
348
349 // Proclaim serial compatibility with 1.4 FCS
350 private static final long serialVersionUID = 276966692217360283L;
351
352 /**
353 * Creates a Field with the specified name.
354 *
355 * @param name Name of the attribute
356 */
357 protected Field(String name) {
358 super(name);
359 }
360 }
361
362
363 /**
364 * FieldDelegate is notified by the various <code>Format</code>
365 * implementations as they are formatting the Objects. This allows for
366 * storage of the individual sections of the formatted String for
367 * later use, such as in a <code>FieldPosition</code> or for an
368 * <code>AttributedCharacterIterator</code>.
369 * <p>
370 * Delegates should NOT assume that the <code>Format</code> will notify
371 * the delegate of fields in any particular order.
372 *
373 * @see FieldPosition#getFieldDelegate
374 * @see CharacterIteratorFieldDelegate
375 */
376 interface FieldDelegate {
377 /**
378 * Notified when a particular region of the String is formatted. This
379 * method will be invoked if there is no corresponding integer field id
380 * matching <code>attr</code>.
381 *
382 * @param attr Identifies the field matched
383 * @param value Value associated with the field
384 * @param start Beginning location of the field, will be >= 0
385 * @param end End of the field, will be >= start and <= buffer.length()
386 * @param buffer Contains current formatted value, receiver should
387 * NOT modify it.
388 */
389 public void formatted(Format.Field attr, Object value, int start,
390 int end, StringBuffer buffer);
391
392 /**
393 * Notified when a particular region of the String is formatted.
394 *
395 * @param fieldID Identifies the field by integer
396 * @param attr Identifies the field matched
397 * @param value Value associated with the field
398 * @param start Beginning location of the field, will be >= 0
399 * @param end End of the field, will be >= start and <= buffer.length()
400 * @param buffer Contains current formatted value, receiver should
401 * NOT modify it.
402 */
403 public void formatted(int fieldID, Format.Field attr, Object value,
404 int start, int end, StringBuffer buffer);
405 }
406 }