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 static
094 {
095 for (short i=MIN_CACHE; i <= MAX_CACHE; i++)
096 shortCache[i - MIN_CACHE] = new Short(i);
097 }
098
099 /**
100 * The immutable value of this Short.
101 *
102 * @serial the wrapped short
103 */
104 private final short value;
105
106 /**
107 * Create a <code>Short</code> object representing the value of the
108 * <code>short</code> argument.
109 *
110 * @param value the value to use
111 */
112 public Short(short value)
113 {
114 this.value = value;
115 }
116
117 /**
118 * Create a <code>Short</code> object representing the value of the
119 * argument after conversion to a <code>short</code>.
120 *
121 * @param s the string to convert
122 * @throws NumberFormatException if the String cannot be parsed
123 */
124 public Short(String s)
125 {
126 value = parseShort(s, 10);
127 }
128
129 /**
130 * Converts the <code>short</code> to a <code>String</code> and assumes
131 * a radix of 10.
132 *
133 * @param s the <code>short</code> to convert to <code>String</code>
134 * @return the <code>String</code> representation of the argument
135 */
136 public static String toString(short s)
137 {
138 return String.valueOf(s);
139 }
140
141 /**
142 * Converts the specified <code>String</code> into a <code>short</code>.
143 * This function assumes a radix of 10.
144 *
145 * @param s the <code>String</code> to convert
146 * @return the <code>short</code> value of <code>s</code>
147 * @throws NumberFormatException if <code>s</code> cannot be parsed as a
148 * <code>short</code>
149 */
150 public static short parseShort(String s)
151 {
152 return parseShort(s, 10);
153 }
154
155 /**
156 * Converts the specified <code>String</code> into a <code>short</code>
157 * using the specified radix (base). The string must not be <code>null</code>
158 * or empty. It may begin with an optional '-', which will negate the answer,
159 * provided that there are also valid digits. Each digit is parsed as if by
160 * <code>Character.digit(d, radix)</code>, and must be in the range
161 * <code>0</code> to <code>radix - 1</code>. Finally, the result must be
162 * within <code>MIN_VALUE</code> to <code>MAX_VALUE</code>, inclusive.
163 * Unlike Double.parseDouble, you may not have a leading '+'.
164 *
165 * @param s the <code>String</code> to convert
166 * @param radix the radix (base) to use in the conversion
167 * @return the <code>String</code> argument converted to <code>short</code>
168 * @throws NumberFormatException if <code>s</code> cannot be parsed as a
169 * <code>short</code>
170 */
171 public static short parseShort(String s, int radix)
172 {
173 int i = Integer.parseInt(s, radix, false);
174 if ((short) i != i)
175 throw new NumberFormatException();
176 return (short) i;
177 }
178
179 /**
180 * Creates a new <code>Short</code> object using the <code>String</code>
181 * and specified radix (base).
182 *
183 * @param s the <code>String</code> to convert
184 * @param radix the radix (base) to convert with
185 * @return the new <code>Short</code>
186 * @throws NumberFormatException if <code>s</code> cannot be parsed as a
187 * <code>short</code>
188 * @see #parseShort(String, int)
189 */
190 public static Short valueOf(String s, int radix)
191 {
192 return valueOf(parseShort(s, radix));
193 }
194
195 /**
196 * Creates a new <code>Short</code> object using the <code>String</code>,
197 * assuming a radix of 10.
198 *
199 * @param s the <code>String</code> to convert
200 * @return the new <code>Short</code>
201 * @throws NumberFormatException if <code>s</code> cannot be parsed as a
202 * <code>short</code>
203 * @see #Short(String)
204 * @see #parseShort(String)
205 */
206 public static Short valueOf(String s)
207 {
208 return valueOf(parseShort(s, 10));
209 }
210
211 /**
212 * Returns a <code>Short</code> object wrapping the value.
213 * In contrast to the <code>Short</code> constructor, this method
214 * will cache some values. It is used by boxing conversion.
215 *
216 * @param val the value to wrap
217 * @return the <code>Short</code>
218 * @since 1.5
219 */
220 public static Short valueOf(short val)
221 {
222 if (val < MIN_CACHE || val > MAX_CACHE)
223 return new Short(val);
224 else
225 return shortCache[val - MIN_CACHE];
226 }
227
228 /**
229 * Convert the specified <code>String</code> into a <code>Short</code>.
230 * The <code>String</code> may represent decimal, hexadecimal, or
231 * octal numbers.
232 *
233 * <p>The extended BNF grammar is as follows:<br>
234 * <pre>
235 * <em>DecodableString</em>:
236 * ( [ <code>-</code> ] <em>DecimalNumber</em> )
237 * | ( [ <code>-</code> ] ( <code>0x</code> | <code>0X</code>
238 * | <code>#</code> ) <em>HexDigit</em> { <em>HexDigit</em> } )
239 * | ( [ <code>-</code> ] <code>0</code> { <em>OctalDigit</em> } )
240 * <em>DecimalNumber</em>:
241 * <em>DecimalDigit except '0'</em> { <em>DecimalDigit</em> }
242 * <em>DecimalDigit</em>:
243 * <em>Character.digit(d, 10) has value 0 to 9</em>
244 * <em>OctalDigit</em>:
245 * <em>Character.digit(d, 8) has value 0 to 7</em>
246 * <em>DecimalDigit</em>:
247 * <em>Character.digit(d, 16) has value 0 to 15</em>
248 * </pre>
249 * Finally, the value must be in the range <code>MIN_VALUE</code> to
250 * <code>MAX_VALUE</code>, or an exception is thrown.
251 *
252 * @param s the <code>String</code> to interpret
253 * @return the value of the String as a <code>Short</code>
254 * @throws NumberFormatException if <code>s</code> cannot be parsed as a
255 * <code>short</code>
256 * @throws NullPointerException if <code>s</code> is null
257 * @see Integer#decode(String)
258 */
259 public static Short decode(String s)
260 {
261 int i = Integer.parseInt(s, 10, true);
262 if ((short) i != i)
263 throw new NumberFormatException();
264 return valueOf((short) i);
265 }
266
267 /**
268 * Return the value of this <code>Short</code> as a <code>byte</code>.
269 *
270 * @return the byte value
271 */
272 public byte byteValue()
273 {
274 return (byte) value;
275 }
276
277 /**
278 * Return the value of this <code>Short</code>.
279 *
280 * @return the short value
281 */
282 public short shortValue()
283 {
284 return value;
285 }
286
287 /**
288 * Return the value of this <code>Short</code> as an <code>int</code>.
289 *
290 * @return the int value
291 */
292 public int intValue()
293 {
294 return value;
295 }
296
297 /**
298 * Return the value of this <code>Short</code> as a <code>long</code>.
299 *
300 * @return the long value
301 */
302 public long longValue()
303 {
304 return value;
305 }
306
307 /**
308 * Return the value of this <code>Short</code> as a <code>float</code>.
309 *
310 * @return the float value
311 */
312 public float floatValue()
313 {
314 return value;
315 }
316
317 /**
318 * Return the value of this <code>Short</code> as a <code>double</code>.
319 *
320 * @return the double value
321 */
322 public double doubleValue()
323 {
324 return value;
325 }
326
327 /**
328 * Converts the <code>Short</code> value to a <code>String</code> and
329 * assumes a radix of 10.
330 *
331 * @return the <code>String</code> representation of this <code>Short</code>
332 */
333 public String toString()
334 {
335 return String.valueOf(value);
336 }
337
338 /**
339 * Return a hashcode representing this Object. <code>Short</code>'s hash
340 * code is simply its value.
341 *
342 * @return this Object's hash code
343 */
344 public int hashCode()
345 {
346 return value;
347 }
348
349 /**
350 * Returns <code>true</code> if <code>obj</code> is an instance of
351 * <code>Short</code> and represents the same short value.
352 *
353 * @param obj the object to compare
354 * @return whether these Objects are semantically equal
355 */
356 public boolean equals(Object obj)
357 {
358 return obj instanceof Short && value == ((Short) obj).value;
359 }
360
361 /**
362 * Compare two Shorts numerically by comparing their <code>short</code>
363 * values. The result is positive if the first is greater, negative if the
364 * second is greater, and 0 if the two are equal.
365 *
366 * @param s the Short to compare
367 * @return the comparison
368 * @since 1.2
369 */
370 public int compareTo(Short s)
371 {
372 return value - s.value;
373 }
374
375 /**
376 * Reverse the bytes in val.
377 * @since 1.5
378 */
379 public static short reverseBytes(short val)
380 {
381 return (short) (((val >> 8) & 0xff) | ((val << 8) & 0xff00));
382 }
383 }