/libjava/classpath/java/lang/Short.java

  1/* Short.java -- object wrapper for short
  2   Copyright (C) 1998, 2001, 2002, 2004, 2005 Free Software Foundation, Inc.
  3
  4This file is part of GNU Classpath.
  5
  6GNU Classpath is free software; you can redistribute it and/or modify
  7it under the terms of the GNU General Public License as published by
  8the Free Software Foundation; either version 2, or (at your option)
  9any later version.
 10
 11GNU Classpath is distributed in the hope that it will be useful, but
 12WITHOUT ANY WARRANTY; without even the implied warranty of
 13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 14General Public License for more details.
 15
 16You should have received a copy of the GNU General Public License
 17along with GNU Classpath; see the file COPYING.  If not, write to the
 18Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 1902110-1301 USA.
 20
 21Linking this library statically or dynamically with other modules is
 22making a combined work based on this library.  Thus, the terms and
 23conditions of the GNU General Public License cover the whole
 24combination.
 25
 26As a special exception, the copyright holders of this library give you
 27permission to link this library with independent modules to produce an
 28executable, regardless of the license terms of these independent
 29modules, and to copy and distribute the resulting executable under
 30terms of your choice, provided that you also meet, for each linked
 31independent module, the terms and conditions of the license of that
 32module.  An independent module is a module which is not derived from
 33or based on this library.  If you modify this library, you may extend
 34this exception to your version of the library, but you are not
 35obligated to do so.  If you do not wish to do so, delete this
 36exception statement from your version. */
 37
 38
 39package java.lang;
 40
 41/**
 42 * Instances of class <code>Short</code> represent primitive
 43 * <code>short</code> values.
 44 *
 45 * Additionally, this class provides various helper functions and variables
 46 * related to shorts.
 47 *
 48 * @author Paul Fisher
 49 * @author John Keiser
 50 * @author Eric Blake (ebb9@email.byu.edu)
 51 * @author Tom Tromey (tromey@redhat.com)
 52 * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
 53 * @since 1.1
 54 * @status updated to 1.5
 55 */
 56public final class Short extends Number implements Comparable<Short>
 57{
 58  /**
 59   * Compatible with JDK 1.1+.
 60   */
 61  private static final long serialVersionUID = 7515723908773894738L;
 62
 63  /**
 64   * The minimum value a <code>short</code> can represent is -32768 (or
 65   * -2<sup>15</sup>).
 66   */
 67  public static final short MIN_VALUE = -32768;
 68
 69  /**
 70   * The minimum value a <code>short</code> can represent is 32767 (or
 71   * 2<sup>15</sup>).
 72   */
 73  public static final short MAX_VALUE = 32767;
 74
 75  /**
 76   * The primitive type <code>short</code> is represented by this
 77   * <code>Class</code> object.
 78   */
 79  public static final Class<Short> TYPE = (Class<Short>) VMClassLoader.getPrimitiveClass('S');
 80
 81  /**
 82   * The number of bits needed to represent a <code>short</code>.
 83   * @since 1.5
 84   */
 85  public static final int SIZE = 16;
 86
 87  // This caches some Short values, and is used by boxing conversions
 88  // via valueOf().  We must cache at least -128..127; these constants
 89  // control how much we actually cache.
 90  private static final int MIN_CACHE = -128;
 91  private static final int MAX_CACHE = 127;
 92  private static Short[] shortCache = new Short[MAX_CACHE - MIN_CACHE + 1];
 93  static
 94  {
 95    for (short i=MIN_CACHE; i <= MAX_CACHE; i++)
 96      shortCache[i - MIN_CACHE] = new Short(i);
 97  }
 98
 99  /**
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   * Compares two unboxed short values.
377   * The result is positive if the first is greater, negative if the second
378   * is greater, and 0 if the two are equal.
379   *
380   * @param x First value to compare.
381   * @param y Second value to compare.
382   *
383   * @return positive int if the first value is greater, negative if the second
384   * is greater, and 0 if the two are equal.
385   * @since 1.7
386   */
387  public static int compare(short x, short y)
388  {
389    return Short.valueOf(x).compareTo(Short.valueOf(y));
390  }
391
392  /**
393   * Reverse the bytes in val.
394   * @since 1.5
395   */
396  public static short reverseBytes(short val)
397  {
398    return (short) (((val >> 8) & 0xff) | ((val << 8) & 0xff00));
399  }
400}