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1 14 jlechner
/* Double.java -- object wrapper for double
2
   Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2005, 2006
3
   Free Software Foundation, Inc.
4
 
5
This file is part of GNU Classpath.
6
 
7
GNU Classpath is free software; you can redistribute it and/or modify
8
it under the terms of the GNU General Public License as published by
9
the Free Software Foundation; either version 2, or (at your option)
10
any later version.
11
 
12
GNU Classpath is distributed in the hope that it will be useful, but
13
WITHOUT ANY WARRANTY; without even the implied warranty of
14
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15
General Public License for more details.
16
 
17
You should have received a copy of the GNU General Public License
18
along with GNU Classpath; see the file COPYING.  If not, write to the
19
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
20
02110-1301 USA.
21
 
22
Linking this library statically or dynamically with other modules is
23
making a combined work based on this library.  Thus, the terms and
24
conditions of the GNU General Public License cover the whole
25
combination.
26
 
27
As a special exception, the copyright holders of this library give you
28
permission to link this library with independent modules to produce an
29
executable, regardless of the license terms of these independent
30
modules, and to copy and distribute the resulting executable under
31
terms of your choice, provided that you also meet, for each linked
32
independent module, the terms and conditions of the license of that
33
module.  An independent module is a module which is not derived from
34
or based on this library.  If you modify this library, you may extend
35
this exception to your version of the library, but you are not
36
obligated to do so.  If you do not wish to do so, delete this
37
exception statement from your version. */
38
 
39
package java.lang;
40
 
41
 
42
/**
43
 * Instances of class <code>Double</code> represent primitive
44
 * <code>double</code> values.
45
 *
46
 * Additionally, this class provides various helper functions and variables
47
 * related to doubles.
48
 *
49
 * @author Paul Fisher
50
 * @author Andrew Haley (aph@cygnus.com)
51
 * @author Eric Blake (ebb9@email.byu.edu)
52
 * @since 1.0
53
 * @status updated to 1.4
54
 */
55
public final class Double extends Number implements Comparable
56
{
57
  /**
58
   * Compatible with JDK 1.0+.
59
   */
60
  private static final long serialVersionUID = -9172774392245257468L;
61
 
62
  /**
63
   * The maximum positive value a <code>double</code> may represent
64
   * is 1.7976931348623157e+308.
65
   */
66
  public static final double MAX_VALUE = 1.7976931348623157e+308;
67
 
68
  /**
69
   * The minimum positive value a <code>double</code> may represent
70
   * is 5e-324.
71
   */
72
  public static final double MIN_VALUE = 5e-324;
73
 
74
  /**
75
   * The value of a double representation -1.0/0.0, negative
76
   * infinity.
77
   */
78
  public static final double NEGATIVE_INFINITY = -1.0 / 0.0;
79
 
80
  /**
81
   * The value of a double representing 1.0/0.0, positive infinity.
82
   */
83
  public static final double POSITIVE_INFINITY = 1.0 / 0.0;
84
 
85
  /**
86
   * All IEEE 754 values of NaN have the same value in Java.
87
   */
88
  public static final double NaN = 0.0 / 0.0;
89
 
90
  /**
91
   * The number of bits needed to represent a <code>double</code>.
92
   * @since 1.5
93
   */
94
  public static final int SIZE = 64;
95
 
96
  /**
97
   * The primitive type <code>double</code> is represented by this
98
   * <code>Class</code> object.
99
   * @since 1.1
100
   */
101
  public static final Class TYPE = VMClassLoader.getPrimitiveClass('D');
102
 
103
  /**
104
   * The immutable value of this Double.
105
   *
106
   * @serial the wrapped double
107
   */
108
  private final double value;
109
 
110
  /**
111
   * Create a <code>Double</code> from the primitive <code>double</code>
112
   * specified.
113
   *
114
   * @param value the <code>double</code> argument
115
   */
116
  public Double(double value)
117
  {
118
    this.value = value;
119
  }
120
 
121
  /**
122
   * Create a <code>Double</code> from the specified <code>String</code>.
123
   * This method calls <code>Double.parseDouble()</code>.
124
   *
125
   * @param s the <code>String</code> to convert
126
   * @throws NumberFormatException if <code>s</code> cannot be parsed as a
127
   *         <code>double</code>
128
   * @throws NullPointerException if <code>s</code> is null
129
   * @see #parseDouble(String)
130
   */
131
  public Double(String s)
132
  {
133
    value = parseDouble(s);
134
  }
135
 
136
  /**
137
   * Convert the <code>double</code> to a <code>String</code>.
138
   * Floating-point string representation is fairly complex: here is a
139
   * rundown of the possible values.  "<code>[-]</code>" indicates that a
140
   * negative sign will be printed if the value (or exponent) is negative.
141
   * "<code>&lt;number&gt;</code>" means a string of digits ('0' to '9').
142
   * "<code>&lt;digit&gt;</code>" means a single digit ('0' to '9').<br>
143
   *
144
   * <table border=1>
145
   * <tr><th>Value of Double</th><th>String Representation</th></tr>
146
   * <tr><td>[+-] 0</td> <td><code>[-]0.0</code></td></tr>
147
   * <tr><td>Between [+-] 10<sup>-3</sup> and 10<sup>7</sup>, exclusive</td>
148
   *     <td><code>[-]number.number</code></td></tr>
149
   * <tr><td>Other numeric value</td>
150
   *     <td><code>[-]&lt;digit&gt;.&lt;number&gt;
151
   *          E[-]&lt;number&gt;</code></td></tr>
152
   * <tr><td>[+-] infinity</td> <td><code>[-]Infinity</code></td></tr>
153
   * <tr><td>NaN</td> <td><code>NaN</code></td></tr>
154
   * </table>
155
   *
156
   * Yes, negative zero <em>is</em> a possible value.  Note that there is
157
   * <em>always</em> a <code>.</code> and at least one digit printed after
158
   * it: even if the number is 3, it will be printed as <code>3.0</code>.
159
   * After the ".", all digits will be printed except trailing zeros. The
160
   * result is rounded to the shortest decimal number which will parse back
161
   * to the same double.
162
   *
163
   * <p>To create other output formats, use {@link java.text.NumberFormat}.
164
   *
165
   * @XXX specify where we are not in accord with the spec.
166
   *
167
   * @param d the <code>double</code> to convert
168
   * @return the <code>String</code> representing the <code>double</code>
169
   */
170
  public static String toString(double d)
171
  {
172
    return toString(d, false);
173
  }
174
 
175
  /**
176
   * Returns a <code>Double</code> object wrapping the value.
177
   * In contrast to the <code>Double</code> constructor, this method
178
   * may cache some values.  It is used by boxing conversion.
179
   *
180
   * @param val the value to wrap
181
   * @return the <code>Double</code>
182
   *
183
   * @since 1.5
184
   */
185
  public static Double valueOf(double val)
186
  {
187
    // We don't actually cache, but we could.
188
    return new Double(val);
189
  }
190
 
191
  /**
192
   * Create a new <code>Double</code> object using the <code>String</code>.
193
   *
194
   * @param s the <code>String</code> to convert
195
   * @return the new <code>Double</code>
196
   * @throws NumberFormatException if <code>s</code> cannot be parsed as a
197
   *         <code>double</code>
198
   * @throws NullPointerException if <code>s</code> is null.
199
   * @see #parseDouble(String)
200
   */
201
  public static Double valueOf(String s)
202
  {
203
    return new Double(parseDouble(s));
204
  }
205
 
206
  /**
207
   * Parse the specified <code>String</code> as a <code>double</code>. The
208
   * extended BNF grammar is as follows:<br>
209
   * <pre>
210
   * <em>DecodableString</em>:
211
   *      ( [ <code>-</code> | <code>+</code> ] <code>NaN</code> )
212
   *    | ( [ <code>-</code> | <code>+</code> ] <code>Infinity</code> )
213
   *    | ( [ <code>-</code> | <code>+</code> ] <em>FloatingPoint</em>
214
   *              [ <code>f</code> | <code>F</code> | <code>d</code>
215
   *                | <code>D</code>] )
216
   * <em>FloatingPoint</em>:
217
   *      ( { <em>Digit</em> }+ [ <code>.</code> { <em>Digit</em> } ]
218
   *              [ <em>Exponent</em> ] )
219
   *    | ( <code>.</code> { <em>Digit</em> }+ [ <em>Exponent</em> ] )
220
   * <em>Exponent</em>:
221
   *      ( ( <code>e</code> | <code>E</code> )
222
   *              [ <code>-</code> | <code>+</code> ] { <em>Digit</em> }+ )
223
   * <em>Digit</em>: <em><code>'0'</code> through <code>'9'</code></em>
224
   * </pre>
225
   *
226
   * <p>NaN and infinity are special cases, to allow parsing of the output
227
   * of toString.  Otherwise, the result is determined by calculating
228
   * <em>n * 10<sup>exponent</sup></em> to infinite precision, then rounding
229
   * to the nearest double. Remember that many numbers cannot be precisely
230
   * represented in floating point. In case of overflow, infinity is used,
231
   * and in case of underflow, signed zero is used. Unlike Integer.parseInt,
232
   * this does not accept Unicode digits outside the ASCII range.
233
   *
234
   * <p>If an unexpected character is found in the <code>String</code>, a
235
   * <code>NumberFormatException</code> will be thrown.  Leading and trailing
236
   * 'whitespace' is ignored via <code>String.trim()</code>, but spaces
237
   * internal to the actual number are not allowed.
238
   *
239
   * <p>To parse numbers according to another format, consider using
240
   * {@link java.text.NumberFormat}.
241
   *
242
   * @XXX specify where/how we are not in accord with the spec.
243
   *
244
   * @param str the <code>String</code> to convert
245
   * @return the <code>double</code> value of <code>s</code>
246
   * @throws NumberFormatException if <code>s</code> cannot be parsed as a
247
   *         <code>double</code>
248
   * @throws NullPointerException if <code>s</code> is null
249
   * @see #MIN_VALUE
250
   * @see #MAX_VALUE
251
   * @see #POSITIVE_INFINITY
252
   * @see #NEGATIVE_INFINITY
253
   * @since 1.2
254
   */
255
  public static native double parseDouble(String str);
256
 
257
  /**
258
   * Return <code>true</code> if the <code>double</code> has the same
259
   * value as <code>NaN</code>, otherwise return <code>false</code>.
260
   *
261
   * @param v the <code>double</code> to compare
262
   * @return whether the argument is <code>NaN</code>.
263
   */
264
  public static boolean isNaN(double v)
265
  {
266
    // This works since NaN != NaN is the only reflexive inequality
267
    // comparison which returns true.
268
    return v != v;
269
  }
270
 
271
  /**
272
   * Return <code>true</code> if the <code>double</code> has a value
273
   * equal to either <code>NEGATIVE_INFINITY</code> or
274
   * <code>POSITIVE_INFINITY</code>, otherwise return <code>false</code>.
275
   *
276
   * @param v the <code>double</code> to compare
277
   * @return whether the argument is (-/+) infinity.
278
   */
279
  public static boolean isInfinite(double v)
280
  {
281
    return v == POSITIVE_INFINITY || v == NEGATIVE_INFINITY;
282
  }
283
 
284
  /**
285
   * Return <code>true</code> if the value of this <code>Double</code>
286
   * is the same as <code>NaN</code>, otherwise return <code>false</code>.
287
   *
288
   * @return whether this <code>Double</code> is <code>NaN</code>
289
   */
290
  public boolean isNaN()
291
  {
292
    return isNaN(value);
293
  }
294
 
295
  /**
296
   * Return <code>true</code> if the value of this <code>Double</code>
297
   * is the same as <code>NEGATIVE_INFINITY</code> or
298
   * <code>POSITIVE_INFINITY</code>, otherwise return <code>false</code>.
299
   *
300
   * @return whether this <code>Double</code> is (-/+) infinity
301
   */
302
  public boolean isInfinite()
303
  {
304
    return isInfinite(value);
305
  }
306
 
307
  /**
308
   * Convert the <code>double</code> value of this <code>Double</code>
309
   * to a <code>String</code>.  This method calls
310
   * <code>Double.toString(double)</code> to do its dirty work.
311
   *
312
   * @return the <code>String</code> representation
313
   * @see #toString(double)
314
   */
315
  public String toString()
316
  {
317
    return toString(value);
318
  }
319
 
320
  /**
321
   * Return the value of this <code>Double</code> as a <code>byte</code>.
322
   *
323
   * @return the byte value
324
   * @since 1.1
325
   */
326
  public byte byteValue()
327
  {
328
    return (byte) value;
329
  }
330
 
331
  /**
332
   * Return the value of this <code>Double</code> as a <code>short</code>.
333
   *
334
   * @return the short value
335
   * @since 1.1
336
   */
337
  public short shortValue()
338
  {
339
    return (short) value;
340
  }
341
 
342
  /**
343
   * Return the value of this <code>Double</code> as an <code>int</code>.
344
   *
345
   * @return the int value
346
   */
347
  public int intValue()
348
  {
349
    return (int) value;
350
  }
351
 
352
  /**
353
   * Return the value of this <code>Double</code> as a <code>long</code>.
354
   *
355
   * @return the long value
356
   */
357
  public long longValue()
358
  {
359
    return (long) value;
360
  }
361
 
362
  /**
363
   * Return the value of this <code>Double</code> as a <code>float</code>.
364
   *
365
   * @return the float value
366
   */
367
  public float floatValue()
368
  {
369
    return (float) value;
370
  }
371
 
372
  /**
373
   * Return the value of this <code>Double</code>.
374
   *
375
   * @return the double value
376
   */
377
  public double doubleValue()
378
  {
379
    return value;
380
  }
381
 
382
  /**
383
   * Return a hashcode representing this Object. <code>Double</code>'s hash
384
   * code is calculated by:<br>
385
   * <code>long v = Double.doubleToLongBits(doubleValue());<br>
386
   *    int hash = (int)(v^(v&gt;&gt;32))</code>.
387
   *
388
   * @return this Object's hash code
389
   * @see #doubleToLongBits(double)
390
   */
391
  public int hashCode()
392
  {
393
    long v = doubleToLongBits(value);
394
    return (int) (v ^ (v >>> 32));
395
  }
396
 
397
  /**
398
   * Returns <code>true</code> if <code>obj</code> is an instance of
399
   * <code>Double</code> and represents the same double value. Unlike comparing
400
   * two doubles with <code>==</code>, this treats two instances of
401
   * <code>Double.NaN</code> as equal, but treats <code>0.0</code> and
402
   * <code>-0.0</code> as unequal.
403
   *
404
   * <p>Note that <code>d1.equals(d2)</code> is identical to
405
   * <code>doubleToLongBits(d1.doubleValue()) ==
406
   *    doubleToLongBits(d2.doubleValue())</code>.
407
   *
408
   * @param obj the object to compare
409
   * @return whether the objects are semantically equal
410
   */
411
  public boolean equals(Object obj)
412
  {
413
    if (! (obj instanceof Double))
414
      return false;
415
 
416
    double d = ((Double) obj).value;
417
 
418
    // Avoid call to native method. However, some implementations, like gcj,
419
    // are better off using floatToIntBits(value) == floatToIntBits(f).
420
    // Check common case first, then check NaN and 0.
421
    if (value == d)
422
      return (value != 0) || (1 / value == 1 / d);
423
    return isNaN(value) && isNaN(d);
424
  }
425
 
426
  /**
427
   * Convert the double to the IEEE 754 floating-point "double format" bit
428
   * layout. Bit 63 (the most significant) is the sign bit, bits 62-52
429
   * (masked by 0x7ff0000000000000L) represent the exponent, and bits 51-0
430
   * (masked by 0x000fffffffffffffL) are the mantissa. This function
431
   * collapses all versions of NaN to 0x7ff8000000000000L. The result of this
432
   * function can be used as the argument to
433
   * <code>Double.longBitsToDouble(long)</code> to obtain the original
434
   * <code>double</code> value.
435
   *
436
   * @param value the <code>double</code> to convert
437
   * @return the bits of the <code>double</code>
438
   * @see #longBitsToDouble(long)
439
   */
440
  // GCJ LOCAL: We diverge from Classpath for efficiency.
441
  public static native long doubleToLongBits(double value);
442
  // END GCJ LOCAL
443
 
444
  /**
445
   * Convert the double to the IEEE 754 floating-point "double format" bit
446
   * layout. Bit 63 (the most significant) is the sign bit, bits 62-52
447
   * (masked by 0x7ff0000000000000L) represent the exponent, and bits 51-0
448
   * (masked by 0x000fffffffffffffL) are the mantissa. This function
449
   * leaves NaN alone, rather than collapsing to a canonical value. The
450
   * result of this function can be used as the argument to
451
   * <code>Double.longBitsToDouble(long)</code> to obtain the original
452
   * <code>double</code> value.
453
   *
454
   * @param value the <code>double</code> to convert
455
   * @return the bits of the <code>double</code>
456
   * @see #longBitsToDouble(long)
457
   */
458
  // GCJ LOCAL: We diverge from Classpath for efficiency.
459
  public static native long doubleToRawLongBits(double value);
460
  // END GCJ LOCAL
461
 
462
  /**
463
   * Convert the argument in IEEE 754 floating-point "double format" bit
464
   * layout to the corresponding float. Bit 63 (the most significant) is the
465
   * sign bit, bits 62-52 (masked by 0x7ff0000000000000L) represent the
466
   * exponent, and bits 51-0 (masked by 0x000fffffffffffffL) are the mantissa.
467
   * This function leaves NaN alone, so that you can recover the bit pattern
468
   * with <code>Double.doubleToRawLongBits(double)</code>.
469
   *
470
   * @param bits the bits to convert
471
   * @return the <code>double</code> represented by the bits
472
   * @see #doubleToLongBits(double)
473
   * @see #doubleToRawLongBits(double)
474
   */
475
  // GCJ LOCAL: We diverge from Classpath for efficiency.
476
  public static native double longBitsToDouble(long bits);
477
  // END GCJ LOCAL
478
 
479
  /**
480
   * Compare two Doubles numerically by comparing their <code>double</code>
481
   * values. The result is positive if the first is greater, negative if the
482
   * second is greater, and 0 if the two are equal. However, this special
483
   * cases NaN and signed zero as follows: NaN is considered greater than
484
   * all other doubles, including <code>POSITIVE_INFINITY</code>, and positive
485
   * zero is considered greater than negative zero.
486
   *
487
   * @param d the Double to compare
488
   * @return the comparison
489
   * @since 1.2
490
   */
491
  public int compareTo(Double d)
492
  {
493
    return compare(value, d.value);
494
  }
495
 
496
  /**
497
   * Behaves like <code>compareTo(Double)</code> unless the Object
498
   * is not an <code>Double</code>.
499
   *
500
   * @param o the object to compare
501
   * @return the comparison
502
   * @throws ClassCastException if the argument is not a <code>Double</code>
503
   * @see #compareTo(Double)
504
   * @see Comparable
505
   * @since 1.2
506
   */
507
  public int compareTo(Object o)
508
  {
509
    return compare(value, ((Double) o).value);
510
  }
511
 
512
  /**
513
   * Behaves like <code>new Double(x).compareTo(new Double(y))</code>; in
514
   * other words this compares two doubles, special casing NaN and zero,
515
   * without the overhead of objects.
516
   *
517
   * @param x the first double to compare
518
   * @param y the second double to compare
519
   * @return the comparison
520
   * @since 1.4
521
   */
522
  public static int compare(double x, double y)
523
  {
524
    if (isNaN(x))
525
      return isNaN(y) ? 0 : 1;
526
    if (isNaN(y))
527
      return -1;
528
    // recall that 0.0 == -0.0, so we convert to infinites and try again
529
    if (x == 0 && y == 0)
530
      return (int) (1 / x - 1 / y);
531
    if (x == y)
532
      return 0;
533
 
534
    return x > y ? 1 : -1;
535
  }
536
 
537
  /**
538
   * Helper method to convert to string.
539
   *
540
   * @param d the double to convert
541
   * @param isFloat true if the conversion is requested by Float (results in
542
   *        fewer digits)
543
   */
544
  // Package visible for use by Float.
545
  static native String toString(double d, boolean isFloat);
546
}

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