001 /* Short.java -- object wrapper for short
002 Copyright (C) 1998, 2001, 2002, 2004, 2005 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.lang;
040
041 /**
042 * Instances of class <code>Short</code> represent primitive
043 * <code>short</code> values.
044 *
045 * Additionally, this class provides various helper functions and variables
046 * related to shorts.
047 *
048 * @author Paul Fisher
049 * @author John Keiser
050 * @author Eric Blake (ebb9@email.byu.edu)
051 * @author Tom Tromey (tromey@redhat.com)
052 * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
053 * @since 1.1
054 * @status updated to 1.5
055 */
056 public final class Short extends Number implements Comparable<Short>
057 {
058 /**
059 * Compatible with JDK 1.1+.
060 */
061 private static final long serialVersionUID = 7515723908773894738L;
062
063 /**
064 * The minimum value a <code>short</code> can represent is -32768 (or
065 * -2<sup>15</sup>).
066 */
067 public static final short MIN_VALUE = -32768;
068
069 /**
070 * The minimum value a <code>short</code> can represent is 32767 (or
071 * 2<sup>15</sup>).
072 */
073 public static final short MAX_VALUE = 32767;
074
075 /**
076 * The primitive type <code>short</code> is represented by this
077 * <code>Class</code> object.
078 */
079 public static final Class<Short> TYPE = (Class<Short>) VMClassLoader.getPrimitiveClass('S');
080
081 /**
082 * The number of bits needed to represent a <code>short</code>.
083 * @since 1.5
084 */
085 public static final int SIZE = 16;
086
087 // This caches some Short values, and is used by boxing conversions
088 // via valueOf(). We must cache at least -128..127; these constants
089 // control how much we actually cache.
090 private static final int MIN_CACHE = -128;
091 private static final int MAX_CACHE = 127;
092 private static Short[] shortCache = new Short[MAX_CACHE - MIN_CACHE + 1];
093
094 /**
095 * The immutable value of this Short.
096 *
097 * @serial the wrapped short
098 */
099 private final short value;
100
101 /**
102 * Create a <code>Short</code> object representing the value of the
103 * <code>short</code> argument.
104 *
105 * @param value the value to use
106 */
107 public Short(short value)
108 {
109 this.value = value;
110 }
111
112 /**
113 * Create a <code>Short</code> object representing the value of the
114 * argument after conversion to a <code>short</code>.
115 *
116 * @param s the string to convert
117 * @throws NumberFormatException if the String cannot be parsed
118 */
119 public Short(String s)
120 {
121 value = parseShort(s, 10);
122 }
123
124 /**
125 * Converts the <code>short</code> to a <code>String</code> and assumes
126 * a radix of 10.
127 *
128 * @param s the <code>short</code> to convert to <code>String</code>
129 * @return the <code>String</code> representation of the argument
130 */
131 public static String toString(short s)
132 {
133 return String.valueOf(s);
134 }
135
136 /**
137 * Converts the specified <code>String</code> into a <code>short</code>.
138 * This function assumes a radix of 10.
139 *
140 * @param s the <code>String</code> to convert
141 * @return the <code>short</code> value of <code>s</code>
142 * @throws NumberFormatException if <code>s</code> cannot be parsed as a
143 * <code>short</code>
144 */
145 public static short parseShort(String s)
146 {
147 return parseShort(s, 10);
148 }
149
150 /**
151 * Converts the specified <code>String</code> into a <code>short</code>
152 * using the specified radix (base). The string must not be <code>null</code>
153 * or empty. It may begin with an optional '-', which will negate the answer,
154 * provided that there are also valid digits. Each digit is parsed as if by
155 * <code>Character.digit(d, radix)</code>, and must be in the range
156 * <code>0</code> to <code>radix - 1</code>. Finally, the result must be
157 * within <code>MIN_VALUE</code> to <code>MAX_VALUE</code>, inclusive.
158 * Unlike Double.parseDouble, you may not have a leading '+'.
159 *
160 * @param s the <code>String</code> to convert
161 * @param radix the radix (base) to use in the conversion
162 * @return the <code>String</code> argument converted to <code>short</code>
163 * @throws NumberFormatException if <code>s</code> cannot be parsed as a
164 * <code>short</code>
165 */
166 public static short parseShort(String s, int radix)
167 {
168 int i = Integer.parseInt(s, radix, false);
169 if ((short) i != i)
170 throw new NumberFormatException();
171 return (short) i;
172 }
173
174 /**
175 * Creates a new <code>Short</code> object using the <code>String</code>
176 * and specified radix (base).
177 *
178 * @param s the <code>String</code> to convert
179 * @param radix the radix (base) to convert with
180 * @return the new <code>Short</code>
181 * @throws NumberFormatException if <code>s</code> cannot be parsed as a
182 * <code>short</code>
183 * @see #parseShort(String, int)
184 */
185 public static Short valueOf(String s, int radix)
186 {
187 return new Short(parseShort(s, radix));
188 }
189
190 /**
191 * Creates a new <code>Short</code> object using the <code>String</code>,
192 * assuming a radix of 10.
193 *
194 * @param s the <code>String</code> to convert
195 * @return the new <code>Short</code>
196 * @throws NumberFormatException if <code>s</code> cannot be parsed as a
197 * <code>short</code>
198 * @see #Short(String)
199 * @see #parseShort(String)
200 */
201 public static Short valueOf(String s)
202 {
203 return new Short(parseShort(s, 10));
204 }
205
206 /**
207 * Returns a <code>Short</code> object wrapping the value.
208 * In contrast to the <code>Short</code> constructor, this method
209 * will cache some values. It is used by boxing conversion.
210 *
211 * @param val the value to wrap
212 * @return the <code>Short</code>
213 * @since 1.5
214 */
215 public static Short valueOf(short val)
216 {
217 if (val < MIN_CACHE || val > MAX_CACHE)
218 return new Short(val);
219 synchronized (shortCache)
220 {
221 if (shortCache[val - MIN_CACHE] == null)
222 shortCache[val - MIN_CACHE] = new Short(val);
223 return shortCache[val - MIN_CACHE];
224 }
225 }
226
227 /**
228 * Convert the specified <code>String</code> into a <code>Short</code>.
229 * The <code>String</code> may represent decimal, hexadecimal, or
230 * octal numbers.
231 *
232 * <p>The extended BNF grammar is as follows:<br>
233 * <pre>
234 * <em>DecodableString</em>:
235 * ( [ <code>-</code> ] <em>DecimalNumber</em> )
236 * | ( [ <code>-</code> ] ( <code>0x</code> | <code>0X</code>
237 * | <code>#</code> ) <em>HexDigit</em> { <em>HexDigit</em> } )
238 * | ( [ <code>-</code> ] <code>0</code> { <em>OctalDigit</em> } )
239 * <em>DecimalNumber</em>:
240 * <em>DecimalDigit except '0'</em> { <em>DecimalDigit</em> }
241 * <em>DecimalDigit</em>:
242 * <em>Character.digit(d, 10) has value 0 to 9</em>
243 * <em>OctalDigit</em>:
244 * <em>Character.digit(d, 8) has value 0 to 7</em>
245 * <em>DecimalDigit</em>:
246 * <em>Character.digit(d, 16) has value 0 to 15</em>
247 * </pre>
248 * Finally, the value must be in the range <code>MIN_VALUE</code> to
249 * <code>MAX_VALUE</code>, or an exception is thrown.
250 *
251 * @param s the <code>String</code> to interpret
252 * @return the value of the String as a <code>Short</code>
253 * @throws NumberFormatException if <code>s</code> cannot be parsed as a
254 * <code>short</code>
255 * @throws NullPointerException if <code>s</code> is null
256 * @see Integer#decode(String)
257 */
258 public static Short decode(String s)
259 {
260 int i = Integer.parseInt(s, 10, true);
261 if ((short) i != i)
262 throw new NumberFormatException();
263 return new Short((short) i);
264 }
265
266 /**
267 * Return the value of this <code>Short</code> as a <code>byte</code>.
268 *
269 * @return the byte value
270 */
271 public byte byteValue()
272 {
273 return (byte) value;
274 }
275
276 /**
277 * Return the value of this <code>Short</code>.
278 *
279 * @return the short value
280 */
281 public short shortValue()
282 {
283 return value;
284 }
285
286 /**
287 * Return the value of this <code>Short</code> as an <code>int</code>.
288 *
289 * @return the int value
290 */
291 public int intValue()
292 {
293 return value;
294 }
295
296 /**
297 * Return the value of this <code>Short</code> as a <code>long</code>.
298 *
299 * @return the long value
300 */
301 public long longValue()
302 {
303 return value;
304 }
305
306 /**
307 * Return the value of this <code>Short</code> as a <code>float</code>.
308 *
309 * @return the float value
310 */
311 public float floatValue()
312 {
313 return value;
314 }
315
316 /**
317 * Return the value of this <code>Short</code> as a <code>double</code>.
318 *
319 * @return the double value
320 */
321 public double doubleValue()
322 {
323 return value;
324 }
325
326 /**
327 * Converts the <code>Short</code> value to a <code>String</code> and
328 * assumes a radix of 10.
329 *
330 * @return the <code>String</code> representation of this <code>Short</code>
331 */
332 public String toString()
333 {
334 return String.valueOf(value);
335 }
336
337 /**
338 * Return a hashcode representing this Object. <code>Short</code>'s hash
339 * code is simply its value.
340 *
341 * @return this Object's hash code
342 */
343 public int hashCode()
344 {
345 return value;
346 }
347
348 /**
349 * Returns <code>true</code> if <code>obj</code> is an instance of
350 * <code>Short</code> and represents the same short value.
351 *
352 * @param obj the object to compare
353 * @return whether these Objects are semantically equal
354 */
355 public boolean equals(Object obj)
356 {
357 return obj instanceof Short && value == ((Short) obj).value;
358 }
359
360 /**
361 * Compare two Shorts numerically by comparing their <code>short</code>
362 * values. The result is positive if the first is greater, negative if the
363 * second is greater, and 0 if the two are equal.
364 *
365 * @param s the Short to compare
366 * @return the comparison
367 * @since 1.2
368 */
369 public int compareTo(Short s)
370 {
371 return value - s.value;
372 }
373
374 /**
375 * Reverse the bytes in val.
376 * @since 1.5
377 */
378 public static short reverseBytes(short val)
379 {
380 return (short) (((val >> 8) & 0xff) | ((val << 8) & 0xff00));
381 }
382 }