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