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 - All Rights Reserved
28 * (C) Copyright IBM Corp. 1996 - 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 /**
42 * <code>FieldPosition</code> is a simple class used by <code>Format</code>
43 * and its subclasses to identify fields in formatted output. Fields can
44 * be identified in two ways:
45 * <ul>
46 * <li>By an integer constant, whose names typically end with
47 * <code>_FIELD</code>. The constants are defined in the various
48 * subclasses of <code>Format</code>.
49 * <li>By a <code>Format.Field</code> constant, see <code>ERA_FIELD</code>
50 * and its friends in <code>DateFormat</code> for an example.
51 * </ul>
52 * <p>
53 * <code>FieldPosition</code> keeps track of the position of the
54 * field within the formatted output with two indices: the index
55 * of the first character of the field and the index of the last
56 * character of the field.
57 *
58 * <p>
59 * One version of the <code>format</code> method in the various
60 * <code>Format</code> classes requires a <code>FieldPosition</code>
61 * object as an argument. You use this <code>format</code> method
62 * to perform partial formatting or to get information about the
63 * formatted output (such as the position of a field).
64 *
65 * <p>
66 * If you are interested in the positions of all attributes in the
67 * formatted string use the <code>Format</code> method
68 * <code>formatToCharacterIterator</code>.
69 *
70 * @author Mark Davis
71 * @since 1.1
72 * @see java.text.Format
73 */
74 public class FieldPosition {
75
76 /**
77 * Input: Desired field to determine start and end offsets for.
78 * The meaning depends on the subclass of Format.
79 */
80 int field = 0;
81
82 /**
83 * Output: End offset of field in text.
84 * If the field does not occur in the text, 0 is returned.
85 */
86 int endIndex = 0;
87
88 /**
89 * Output: Start offset of field in text.
90 * If the field does not occur in the text, 0 is returned.
91 */
92 int beginIndex = 0;
93
94 /**
95 * Desired field this FieldPosition is for.
96 */
97 private Format.Field attribute;
98
99 /**
100 * Creates a FieldPosition object for the given field. Fields are
101 * identified by constants, whose names typically end with _FIELD,
102 * in the various subclasses of Format.
103 *
104 * @param field the field identifier
105 * @see java.text.NumberFormat#INTEGER_FIELD
106 * @see java.text.NumberFormat#FRACTION_FIELD
107 * @see java.text.DateFormat#YEAR_FIELD
108 * @see java.text.DateFormat#MONTH_FIELD
109 */
110 public FieldPosition(int field) {
111 this.field = field;
112 }
113
114 /**
115 * Creates a FieldPosition object for the given field constant. Fields are
116 * identified by constants defined in the various <code>Format</code>
117 * subclasses. This is equivalent to calling
118 * <code>new FieldPosition(attribute, -1)</code>.
119 *
120 * @param attribute Format.Field constant identifying a field
121 * @since 1.4
122 */
123 public FieldPosition(Format.Field attribute) {
124 this(attribute, -1);
125 }
126
127 /**
128 * Creates a <code>FieldPosition</code> object for the given field.
129 * The field is identified by an attribute constant from one of the
130 * <code>Field</code> subclasses as well as an integer field ID
131 * defined by the <code>Format</code> subclasses. <code>Format</code>
132 * subclasses that are aware of <code>Field</code> should give precedence
133 * to <code>attribute</code> and ignore <code>fieldID</code> if
134 * <code>attribute</code> is not null. However, older <code>Format</code>
135 * subclasses may not be aware of <code>Field</code> and rely on
136 * <code>fieldID</code>. If the field has no corresponding integer
137 * constant, <code>fieldID</code> should be -1.
138 *
139 * @param attribute Format.Field constant identifying a field
140 * @param fieldID integer constant identifying a field
141 * @since 1.4
142 */
143 public FieldPosition(Format.Field attribute, int fieldID) {
144 this.attribute = attribute;
145 this.field = fieldID;
146 }
147
148 /**
149 * Returns the field identifier as an attribute constant
150 * from one of the <code>Field</code> subclasses. May return null if
151 * the field is specified only by an integer field ID.
152 *
153 * @return Identifier for the field
154 * @since 1.4
155 */
156 public Format.Field getFieldAttribute() {
157 return attribute;
158 }
159
160 /**
161 * Retrieves the field identifier.
162 *
163 * @return the field identifier
164 */
165 public int getField() {
166 return field;
167 }
168
169 /**
170 * Retrieves the index of the first character in the requested field.
171 *
172 * @return the begin index
173 */
174 public int getBeginIndex() {
175 return beginIndex;
176 }
177
178 /**
179 * Retrieves the index of the character following the last character in the
180 * requested field.
181 *
182 * @return the end index
183 */
184 public int getEndIndex() {
185 return endIndex;
186 }
187
188 /**
189 * Sets the begin index. For use by subclasses of Format.
190 *
191 * @param bi the begin index
192 * @since 1.2
193 */
194 public void setBeginIndex(int bi) {
195 beginIndex = bi;
196 }
197
198 /**
199 * Sets the end index. For use by subclasses of Format.
200 *
201 * @param ei the end index
202 * @since 1.2
203 */
204 public void setEndIndex(int ei) {
205 endIndex = ei;
206 }
207
208 /**
209 * Returns a <code>Format.FieldDelegate</code> instance that is associated
210 * with the FieldPosition. When the delegate is notified of the same
211 * field the FieldPosition is associated with, the begin/end will be
212 * adjusted.
213 */
214 Format.FieldDelegate getFieldDelegate() {
215 return new Delegate();
216 }
217
218 /**
219 * Overrides equals
220 */
221 public boolean equals(Object obj)
222 {
223 if (obj == null) return false;
224 if (!(obj instanceof FieldPosition))
225 return false;
226 FieldPosition other = (FieldPosition) obj;
227 if (attribute == null) {
228 if (other.attribute != null) {
229 return false;
230 }
231 }
232 else if (!attribute.equals(other.attribute)) {
233 return false;
234 }
235 return (beginIndex == other.beginIndex
236 && endIndex == other.endIndex
237 && field == other.field);
238 }
239
240 /**
241 * Returns a hash code for this FieldPosition.
242 * @return a hash code value for this object
243 */
244 public int hashCode() {
245 return (field << 24) | (beginIndex << 16) | endIndex;
246 }
247
248 /**
249 * Return a string representation of this FieldPosition.
250 * @return a string representation of this object
251 */
252 public String toString() {
253 return getClass().getName() +
254 "[field=" + field + ",attribute=" + attribute +
255 ",beginIndex=" + beginIndex +
256 ",endIndex=" + endIndex + ']';
257 }
258
259
260 /**
261 * Return true if the receiver wants a <code>Format.Field</code> value and
262 * <code>attribute</code> is equal to it.
263 */
264 private boolean matchesField(Format.Field attribute) {
265 if (this.attribute != null) {
266 return this.attribute.equals(attribute);
267 }
268 return false;
269 }
270
271 /**
272 * Return true if the receiver wants a <code>Format.Field</code> value and
273 * <code>attribute</code> is equal to it, or true if the receiver
274 * represents an inteter constant and <code>field</code> equals it.
275 */
276 private boolean matchesField(Format.Field attribute, int field) {
277 if (this.attribute != null) {
278 return this.attribute.equals(attribute);
279 }
280 return (field == this.field);
281 }
282
283
284 /**
285 * An implementation of FieldDelegate that will adjust the begin/end
286 * of the FieldPosition if the arguments match the field of
287 * the FieldPosition.
288 */
289 private class Delegate implements Format.FieldDelegate {
290 /**
291 * Indicates whether the field has been encountered before. If this
292 * is true, and <code>formatted</code> is invoked, the begin/end
293 * are not updated.
294 */
295 private boolean encounteredField;
296
297 public void formatted(Format.Field attr, Object value, int start,
298 int end, StringBuffer buffer) {
299 if (!encounteredField && matchesField(attr)) {
300 setBeginIndex(start);
301 setEndIndex(end);
302 encounteredField = (start != end);
303 }
304 }
305
306 public void formatted(int fieldID, Format.Field attr, Object value,
307 int start, int end, StringBuffer buffer) {
308 if (!encounteredField && matchesField(attr, fieldID)) {
309 setBeginIndex(start);
310 setEndIndex(end);
311 encounteredField = (start != end);
312 }
313 }
314 }
315 }
316