1 /*
2 * Copyright (c) 1994, 2016, 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 package java.lang;
27
28 import jdk.internal.math.FloatingDecimal;
29 import jdk.internal.HotSpotIntrinsicCandidate;
30
31 /**
32 * The {@code Float} class wraps a value of primitive type
33 * {@code float} in an object. An object of type
34 * {@code Float} contains a single field whose type is
35 * {@code float}.
36 *
37 * <p>In addition, this class provides several methods for converting a
38 * {@code float} to a {@code String} and a
39 * {@code String} to a {@code float}, as well as other
40 * constants and methods useful when dealing with a
41 * {@code float}.
42 *
43 * @author Lee Boynton
44 * @author Arthur van Hoff
45 * @author Joseph D. Darcy
46 * @since 1.0
47 */
48 public final class Float extends Number implements Comparable<Float> {
49 /**
50 * A constant holding the positive infinity of type
51 * {@code float}. It is equal to the value returned by
52 * {@code Float.intBitsToFloat(0x7f800000)}.
53 */
54 public static final float POSITIVE_INFINITY = 1.0f / 0.0f;
55
56 /**
57 * A constant holding the negative infinity of type
58 * {@code float}. It is equal to the value returned by
59 * {@code Float.intBitsToFloat(0xff800000)}.
60 */
61 public static final float NEGATIVE_INFINITY = -1.0f / 0.0f;
62
63 /**
64 * A constant holding a Not-a-Number (NaN) value of type
65 * {@code float}. It is equivalent to the value returned by
66 * {@code Float.intBitsToFloat(0x7fc00000)}.
67 */
68 public static final float NaN = 0.0f / 0.0f;
69
70 /**
71 * A constant holding the largest positive finite value of type
72 * {@code float}, (2-2<sup>-23</sup>)·2<sup>127</sup>.
73 * It is equal to the hexadecimal floating-point literal
74 * {@code 0x1.fffffeP+127f} and also equal to
75 * {@code Float.intBitsToFloat(0x7f7fffff)}.
76 */
77 public static final float MAX_VALUE = 0x1.fffffeP+127f; // 3.4028235e+38f
78
79 /**
80 * A constant holding the smallest positive normal value of type
81 * {@code float}, 2<sup>-126</sup>. It is equal to the
82 * hexadecimal floating-point literal {@code 0x1.0p-126f} and also
83 * equal to {@code Float.intBitsToFloat(0x00800000)}.
84 *
85 * @since 1.6
86 */
87 public static final float MIN_NORMAL = 0x1.0p-126f; // 1.17549435E-38f
88
89 /**
90 * A constant holding the smallest positive nonzero value of type
91 * {@code float}, 2<sup>-149</sup>. It is equal to the
92 * hexadecimal floating-point literal {@code 0x0.000002P-126f}
93 * and also equal to {@code Float.intBitsToFloat(0x1)}.
94 */
95 public static final float MIN_VALUE = 0x0.000002P-126f; // 1.4e-45f
96
97 /**
98 * Maximum exponent a finite {@code float} variable may have. It
99 * is equal to the value returned by {@code
100 * Math.getExponent(Float.MAX_VALUE)}.
101 *
102 * @since 1.6
103 */
104 public static final int MAX_EXPONENT = 127;
105
106 /**
107 * Minimum exponent a normalized {@code float} variable may have.
108 * It is equal to the value returned by {@code
109 * Math.getExponent(Float.MIN_NORMAL)}.
110 *
111 * @since 1.6
112 */
113 public static final int MIN_EXPONENT = -126;
114
115 /**
116 * The number of bits used to represent a {@code float} value.
117 *
118 * @since 1.5
119 */
120 public static final int SIZE = 32;
121
122 /**
123 * The number of bytes used to represent a {@code float} value.
124 *
125 * @since 1.8
126 */
127 public static final int BYTES = SIZE / Byte.SIZE;
128
129 /**
130 * The {@code Class} instance representing the primitive type
131 * {@code float}.
132 *
133 * @since 1.1
134 */
135 @SuppressWarnings("unchecked")
136 public static final Class<Float> TYPE = (Class<Float>) Class.getPrimitiveClass("float");
137
138 /**
139 * Returns a string representation of the {@code float}
140 * argument. All characters mentioned below are ASCII characters.
141 * <ul>
142 * <li>If the argument is NaN, the result is the string
143 * "{@code NaN}".
144 * <li>Otherwise, the result is a string that represents the sign and
145 * magnitude (absolute value) of the argument. If the sign is
146 * negative, the first character of the result is
147 * '{@code -}' ({@code '\u005Cu002D'}); if the sign is
148 * positive, no sign character appears in the result. As for
149 * the magnitude <i>m</i>:
150 * <ul>
151 * <li>If <i>m</i> is infinity, it is represented by the characters
152 * {@code "Infinity"}; thus, positive infinity produces
153 * the result {@code "Infinity"} and negative infinity
154 * produces the result {@code "-Infinity"}.
155 * <li>If <i>m</i> is zero, it is represented by the characters
156 * {@code "0.0"}; thus, negative zero produces the result
157 * {@code "-0.0"} and positive zero produces the result
158 * {@code "0.0"}.
159 * <li> If <i>m</i> is greater than or equal to 10<sup>-3</sup> but
160 * less than 10<sup>7</sup>, then it is represented as the
161 * integer part of <i>m</i>, in decimal form with no leading
162 * zeroes, followed by '{@code .}'
163 * ({@code '\u005Cu002E'}), followed by one or more
164 * decimal digits representing the fractional part of
165 * <i>m</i>.
166 * <li> If <i>m</i> is less than 10<sup>-3</sup> or greater than or
167 * equal to 10<sup>7</sup>, then it is represented in
168 * so-called "computerized scientific notation." Let <i>n</i>
169 * be the unique integer such that 10<sup><i>n</i> </sup>≤
170 * <i>m</i> {@literal <} 10<sup><i>n</i>+1</sup>; then let <i>a</i>
171 * be the mathematically exact quotient of <i>m</i> and
172 * 10<sup><i>n</i></sup> so that 1 ≤ <i>a</i> {@literal <} 10.
173 * The magnitude is then represented as the integer part of
174 * <i>a</i>, as a single decimal digit, followed by
175 * '{@code .}' ({@code '\u005Cu002E'}), followed by
176 * decimal digits representing the fractional part of
177 * <i>a</i>, followed by the letter '{@code E}'
178 * ({@code '\u005Cu0045'}), followed by a representation
179 * of <i>n</i> as a decimal integer, as produced by the
180 * method {@link java.lang.Integer#toString(int)}.
181 *
182 * </ul>
183 * </ul>
184 * How many digits must be printed for the fractional part of
185 * <i>m</i> or <i>a</i>? There must be at least one digit
186 * to represent the fractional part, and beyond that as many, but
187 * only as many, more digits as are needed to uniquely distinguish
188 * the argument value from adjacent values of type
189 * {@code float}. That is, suppose that <i>x</i> is the
190 * exact mathematical value represented by the decimal
191 * representation produced by this method for a finite nonzero
192 * argument <i>f</i>. Then <i>f</i> must be the {@code float}
193 * value nearest to <i>x</i>; or, if two {@code float} values are
194 * equally close to <i>x</i>, then <i>f</i> must be one of
195 * them and the least significant bit of the significand of
196 * <i>f</i> must be {@code 0}.
197 *
198 * <p>To create localized string representations of a floating-point
199 * value, use subclasses of {@link java.text.NumberFormat}.
200 *
201 * @param f the float to be converted.
202 * @return a string representation of the argument.
203 */
204 public static String toString(float f) {
205 return FloatingDecimal.toJavaFormatString(f);
206 }
207
208 /**
209 * Returns a hexadecimal string representation of the
210 * {@code float} argument. All characters mentioned below are
211 * ASCII characters.
212 *
213 * <ul>
214 * <li>If the argument is NaN, the result is the string
215 * "{@code NaN}".
216 * <li>Otherwise, the result is a string that represents the sign and
217 * magnitude (absolute value) of the argument. If the sign is negative,
218 * the first character of the result is '{@code -}'
219 * ({@code '\u005Cu002D'}); if the sign is positive, no sign character
220 * appears in the result. As for the magnitude <i>m</i>:
221 *
222 * <ul>
223 * <li>If <i>m</i> is infinity, it is represented by the string
224 * {@code "Infinity"}; thus, positive infinity produces the
225 * result {@code "Infinity"} and negative infinity produces
226 * the result {@code "-Infinity"}.
227 *
228 * <li>If <i>m</i> is zero, it is represented by the string
229 * {@code "0x0.0p0"}; thus, negative zero produces the result
230 * {@code "-0x0.0p0"} and positive zero produces the result
231 * {@code "0x0.0p0"}.
232 *
233 * <li>If <i>m</i> is a {@code float} value with a
234 * normalized representation, substrings are used to represent the
235 * significand and exponent fields. The significand is
236 * represented by the characters {@code "0x1."}
237 * followed by a lowercase hexadecimal representation of the rest
238 * of the significand as a fraction. Trailing zeros in the
239 * hexadecimal representation are removed unless all the digits
240 * are zero, in which case a single zero is used. Next, the
241 * exponent is represented by {@code "p"} followed
242 * by a decimal string of the unbiased exponent as if produced by
243 * a call to {@link Integer#toString(int) Integer.toString} on the
244 * exponent value.
245 *
246 * <li>If <i>m</i> is a {@code float} value with a subnormal
247 * representation, the significand is represented by the
248 * characters {@code "0x0."} followed by a
249 * hexadecimal representation of the rest of the significand as a
250 * fraction. Trailing zeros in the hexadecimal representation are
251 * removed. Next, the exponent is represented by
252 * {@code "p-126"}. Note that there must be at
253 * least one nonzero digit in a subnormal significand.
254 *
255 * </ul>
256 *
257 * </ul>
258 *
259 * <table border>
260 * <caption>Examples</caption>
261 * <tr><th>Floating-point Value</th><th>Hexadecimal String</th>
262 * <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td>
263 * <tr><td>{@code -1.0}</td> <td>{@code -0x1.0p0}</td>
264 * <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td>
265 * <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td>
266 * <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td>
267 * <tr><td>{@code 0.25}</td> <td>{@code 0x1.0p-2}</td>
268 * <tr><td>{@code Float.MAX_VALUE}</td>
269 * <td>{@code 0x1.fffffep127}</td>
270 * <tr><td>{@code Minimum Normal Value}</td>
271 * <td>{@code 0x1.0p-126}</td>
272 * <tr><td>{@code Maximum Subnormal Value}</td>
273 * <td>{@code 0x0.fffffep-126}</td>
274 * <tr><td>{@code Float.MIN_VALUE}</td>
275 * <td>{@code 0x0.000002p-126}</td>
276 * </table>
277 * @param f the {@code float} to be converted.
278 * @return a hex string representation of the argument.
279 * @since 1.5
280 * @author Joseph D. Darcy
281 */
282 public static String toHexString(float f) {
283 if (Math.abs(f) < Float.MIN_NORMAL
284 && f != 0.0f ) {// float subnormal
285 // Adjust exponent to create subnormal double, then
286 // replace subnormal double exponent with subnormal float
287 // exponent
288 String s = Double.toHexString(Math.scalb((double)f,
289 /* -1022+126 */
290 Double.MIN_EXPONENT-
291 Float.MIN_EXPONENT));
292 return s.replaceFirst("p-1022$", "p-126");
293 }
294 else // double string will be the same as float string
295 return Double.toHexString(f);
296 }
297
298 /**
299 * Returns a {@code Float} object holding the
300 * {@code float} value represented by the argument string
301 * {@code s}.
302 *
303 * <p>If {@code s} is {@code null}, then a
304 * {@code NullPointerException} is thrown.
305 *
306 * <p>Leading and trailing whitespace characters in {@code s}
307 * are ignored. Whitespace is removed as if by the {@link
308 * String#trim} method; that is, both ASCII space and control
309 * characters are removed. The rest of {@code s} should
310 * constitute a <i>FloatValue</i> as described by the lexical
311 * syntax rules:
312 *
313 * <blockquote>
314 * <dl>
315 * <dt><i>FloatValue:</i>
316 * <dd><i>Sign<sub>opt</sub></i> {@code NaN}
317 * <dd><i>Sign<sub>opt</sub></i> {@code Infinity}
318 * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
319 * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
320 * <dd><i>SignedInteger</i>
321 * </dl>
322 *
323 * <dl>
324 * <dt><i>HexFloatingPointLiteral</i>:
325 * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
326 * </dl>
327 *
328 * <dl>
329 * <dt><i>HexSignificand:</i>
330 * <dd><i>HexNumeral</i>
331 * <dd><i>HexNumeral</i> {@code .}
332 * <dd>{@code 0x} <i>HexDigits<sub>opt</sub>
333 * </i>{@code .}<i> HexDigits</i>
334 * <dd>{@code 0X}<i> HexDigits<sub>opt</sub>
335 * </i>{@code .} <i>HexDigits</i>
336 * </dl>
337 *
338 * <dl>
339 * <dt><i>BinaryExponent:</i>
340 * <dd><i>BinaryExponentIndicator SignedInteger</i>
341 * </dl>
342 *
343 * <dl>
344 * <dt><i>BinaryExponentIndicator:</i>
345 * <dd>{@code p}
346 * <dd>{@code P}
347 * </dl>
348 *
349 * </blockquote>
350 *
351 * where <i>Sign</i>, <i>FloatingPointLiteral</i>,
352 * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
353 * <i>FloatTypeSuffix</i> are as defined in the lexical structure
354 * sections of
355 * <cite>The Java™ Language Specification</cite>,
356 * except that underscores are not accepted between digits.
357 * If {@code s} does not have the form of
358 * a <i>FloatValue</i>, then a {@code NumberFormatException}
359 * is thrown. Otherwise, {@code s} is regarded as
360 * representing an exact decimal value in the usual
361 * "computerized scientific notation" or as an exact
362 * hexadecimal value; this exact numerical value is then
363 * conceptually converted to an "infinitely precise"
364 * binary value that is then rounded to type {@code float}
365 * by the usual round-to-nearest rule of IEEE 754 floating-point
366 * arithmetic, which includes preserving the sign of a zero
367 * value.
368 *
369 * Note that the round-to-nearest rule also implies overflow and
370 * underflow behaviour; if the exact value of {@code s} is large
371 * enough in magnitude (greater than or equal to ({@link
372 * #MAX_VALUE} + {@link Math#ulp(float) ulp(MAX_VALUE)}/2),
373 * rounding to {@code float} will result in an infinity and if the
374 * exact value of {@code s} is small enough in magnitude (less
375 * than or equal to {@link #MIN_VALUE}/2), rounding to float will
376 * result in a zero.
377 *
378 * Finally, after rounding a {@code Float} object representing
379 * this {@code float} value is returned.
380 *
381 * <p>To interpret localized string representations of a
382 * floating-point value, use subclasses of {@link
383 * java.text.NumberFormat}.
384 *
385 * <p>Note that trailing format specifiers, specifiers that
386 * determine the type of a floating-point literal
387 * ({@code 1.0f} is a {@code float} value;
388 * {@code 1.0d} is a {@code double} value), do
389 * <em>not</em> influence the results of this method. In other
390 * words, the numerical value of the input string is converted
391 * directly to the target floating-point type. In general, the
392 * two-step sequence of conversions, string to {@code double}
393 * followed by {@code double} to {@code float}, is
394 * <em>not</em> equivalent to converting a string directly to
395 * {@code float}. For example, if first converted to an
396 * intermediate {@code double} and then to
397 * {@code float}, the string<br>
398 * {@code "1.00000017881393421514957253748434595763683319091796875001d"}<br>
399 * results in the {@code float} value
400 * {@code 1.0000002f}; if the string is converted directly to
401 * {@code float}, <code>1.000000<b>1</b>f</code> results.
402 *
403 * <p>To avoid calling this method on an invalid string and having
404 * a {@code NumberFormatException} be thrown, the documentation
405 * for {@link Double#valueOf Double.valueOf} lists a regular
406 * expression which can be used to screen the input.
407 *
408 * @param s the string to be parsed.
409 * @return a {@code Float} object holding the value
410 * represented by the {@code String} argument.
411 * @throws NumberFormatException if the string does not contain a
412 * parsable number.
413 */
414 public static Float valueOf(String s) throws NumberFormatException {
415 return new Float(parseFloat(s));
416 }
417
418 /**
419 * Returns a {@code Float} instance representing the specified
420 * {@code float} value.
421 * If a new {@code Float} instance is not required, this method
422 * should generally be used in preference to the constructor
423 * {@link #Float(float)}, as this method is likely to yield
424 * significantly better space and time performance by caching
425 * frequently requested values.
426 *
427 * @param f a float value.
428 * @return a {@code Float} instance representing {@code f}.
429 * @since 1.5
430 */
431 @HotSpotIntrinsicCandidate
432 public static Float valueOf(float f) {
433 return new Float(f);
434 }
435
436 /**
437 * Returns a new {@code float} initialized to the value
438 * represented by the specified {@code String}, as performed
439 * by the {@code valueOf} method of class {@code Float}.
440 *
441 * @param s the string to be parsed.
442 * @return the {@code float} value represented by the string
443 * argument.
444 * @throws NullPointerException if the string is null
445 * @throws NumberFormatException if the string does not contain a
446 * parsable {@code float}.
447 * @see java.lang.Float#valueOf(String)
448 * @since 1.2
449 */
450 public static float parseFloat(String s) throws NumberFormatException {
451 return FloatingDecimal.parseFloat(s);
452 }
453
454 /**
455 * Returns {@code true} if the specified number is a
456 * Not-a-Number (NaN) value, {@code false} otherwise.
457 *
458 * @param v the value to be tested.
459 * @return {@code true} if the argument is NaN;
460 * {@code false} otherwise.
461 */
462 public static boolean isNaN(float v) {
463 return (v != v);
464 }
465
466 /**
467 * Returns {@code true} if the specified number is infinitely
468 * large in magnitude, {@code false} otherwise.
469 *
470 * @param v the value to be tested.
471 * @return {@code true} if the argument is positive infinity or
472 * negative infinity; {@code false} otherwise.
473 */
474 public static boolean isInfinite(float v) {
475 return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
476 }
477
478
479 /**
480 * Returns {@code true} if the argument is a finite floating-point
481 * value; returns {@code false} otherwise (for NaN and infinity
482 * arguments).
483 *
484 * @param f the {@code float} value to be tested
485 * @return {@code true} if the argument is a finite
486 * floating-point value, {@code false} otherwise.
487 * @since 1.8
488 */
489 public static boolean isFinite(float f) {
490 return Math.abs(f) <= Float.MAX_VALUE;
491 }
492
493 /**
494 * The value of the Float.
495 *
496 * @serial
497 */
498 private final float value;
499
500 /**
501 * Constructs a newly allocated {@code Float} object that
502 * represents the primitive {@code float} argument.
503 *
504 * @param value the value to be represented by the {@code Float}.
505 */
506 public Float(float value) {
507 this.value = value;
508 }
509
510 /**
511 * Constructs a newly allocated {@code Float} object that
512 * represents the argument converted to type {@code float}.
513 *
514 * @param value the value to be represented by the {@code Float}.
515 */
516 public Float(double value) {
517 this.value = (float)value;
518 }
519
520 /**
521 * Constructs a newly allocated {@code Float} object that
522 * represents the floating-point value of type {@code float}
523 * represented by the string. The string is converted to a
524 * {@code float} value as if by the {@code valueOf} method.
525 *
526 * @param s a string to be converted to a {@code Float}.
527 * @throws NumberFormatException if the string does not contain a
528 * parsable number.
529 * @see java.lang.Float#valueOf(java.lang.String)
530 */
531 public Float(String s) throws NumberFormatException {
532 value = parseFloat(s);
533 }
534
535 /**
536 * Returns {@code true} if this {@code Float} value is a
537 * Not-a-Number (NaN), {@code false} otherwise.
538 *
539 * @return {@code true} if the value represented by this object is
540 * NaN; {@code false} otherwise.
541 */
542 public boolean isNaN() {
543 return isNaN(value);
544 }
545
546 /**
547 * Returns {@code true} if this {@code Float} value is
548 * infinitely large in magnitude, {@code false} otherwise.
549 *
550 * @return {@code true} if the value represented by this object is
551 * positive infinity or negative infinity;
552 * {@code false} otherwise.
553 */
554 public boolean isInfinite() {
555 return isInfinite(value);
556 }
557
558 /**
559 * Returns a string representation of this {@code Float} object.
560 * The primitive {@code float} value represented by this object
561 * is converted to a {@code String} exactly as if by the method
562 * {@code toString} of one argument.
563 *
564 * @return a {@code String} representation of this object.
565 * @see java.lang.Float#toString(float)
566 */
567 public String toString() {
568 return Float.toString(value);
569 }
570
571 /**
572 * Returns the value of this {@code Float} as a {@code byte} after
573 * a narrowing primitive conversion.
574 *
575 * @return the {@code float} value represented by this object
576 * converted to type {@code byte}
577 * @jls 5.1.3 Narrowing Primitive Conversions
578 */
579 public byte byteValue() {
580 return (byte)value;
581 }
582
583 /**
584 * Returns the value of this {@code Float} as a {@code short}
585 * after a narrowing primitive conversion.
586 *
587 * @return the {@code float} value represented by this object
588 * converted to type {@code short}
589 * @jls 5.1.3 Narrowing Primitive Conversions
590 * @since 1.1
591 */
592 public short shortValue() {
593 return (short)value;
594 }
595
596 /**
597 * Returns the value of this {@code Float} as an {@code int} after
598 * a narrowing primitive conversion.
599 *
600 * @return the {@code float} value represented by this object
601 * converted to type {@code int}
602 * @jls 5.1.3 Narrowing Primitive Conversions
603 */
604 public int intValue() {
605 return (int)value;
606 }
607
608 /**
609 * Returns value of this {@code Float} as a {@code long} after a
610 * narrowing primitive conversion.
611 *
612 * @return the {@code float} value represented by this object
613 * converted to type {@code long}
614 * @jls 5.1.3 Narrowing Primitive Conversions
615 */
616 public long longValue() {
617 return (long)value;
618 }
619
620 /**
621 * Returns the {@code float} value of this {@code Float} object.
622 *
623 * @return the {@code float} value represented by this object
624 */
625 @HotSpotIntrinsicCandidate
626 public float floatValue() {
627 return value;
628 }
629
630 /**
631 * Returns the value of this {@code Float} as a {@code double}
632 * after a widening primitive conversion.
633 *
634 * @return the {@code float} value represented by this
635 * object converted to type {@code double}
636 * @jls 5.1.2 Widening Primitive Conversions
637 */
638 public double doubleValue() {
639 return (double)value;
640 }
641
642 /**
643 * Returns a hash code for this {@code Float} object. The
644 * result is the integer bit representation, exactly as produced
645 * by the method {@link #floatToIntBits(float)}, of the primitive
646 * {@code float} value represented by this {@code Float}
647 * object.
648 *
649 * @return a hash code value for this object.
650 */
651 @Override
652 public int hashCode() {
653 return Float.hashCode(value);
654 }
655
656 /**
657 * Returns a hash code for a {@code float} value; compatible with
658 * {@code Float.hashCode()}.
659 *
660 * @param value the value to hash
661 * @return a hash code value for a {@code float} value.
662 * @since 1.8
663 */
664 public static int hashCode(float value) {
665 return floatToIntBits(value);
666 }
667
668 /**
669
670 * Compares this object against the specified object. The result
671 * is {@code true} if and only if the argument is not
672 * {@code null} and is a {@code Float} object that
673 * represents a {@code float} with the same value as the
674 * {@code float} represented by this object. For this
675 * purpose, two {@code float} values are considered to be the
676 * same if and only if the method {@link #floatToIntBits(float)}
677 * returns the identical {@code int} value when applied to
678 * each.
679 *
680 * <p>Note that in most cases, for two instances of class
681 * {@code Float}, {@code f1} and {@code f2}, the value
682 * of {@code f1.equals(f2)} is {@code true} if and only if
683 *
684 * <blockquote><pre>
685 * f1.floatValue() == f2.floatValue()
686 * </pre></blockquote>
687 *
688 * <p>also has the value {@code true}. However, there are two exceptions:
689 * <ul>
690 * <li>If {@code f1} and {@code f2} both represent
691 * {@code Float.NaN}, then the {@code equals} method returns
692 * {@code true}, even though {@code Float.NaN==Float.NaN}
693 * has the value {@code false}.
694 * <li>If {@code f1} represents {@code +0.0f} while
695 * {@code f2} represents {@code -0.0f}, or vice
696 * versa, the {@code equal} test has the value
697 * {@code false}, even though {@code 0.0f==-0.0f}
698 * has the value {@code true}.
699 * </ul>
700 *
701 * This definition allows hash tables to operate properly.
702 *
703 * @param obj the object to be compared
704 * @return {@code true} if the objects are the same;
705 * {@code false} otherwise.
706 * @see java.lang.Float#floatToIntBits(float)
707 */
708 public boolean equals(Object obj) {
709 return (obj instanceof Float)
710 && (floatToIntBits(((Float)obj).value) == floatToIntBits(value));
711 }
712
713 /**
714 * Returns a representation of the specified floating-point value
715 * according to the IEEE 754 floating-point "single format" bit
716 * layout.
717 *
718 * <p>Bit 31 (the bit that is selected by the mask
719 * {@code 0x80000000}) represents the sign of the floating-point
720 * number.
721 * Bits 30-23 (the bits that are selected by the mask
722 * {@code 0x7f800000}) represent the exponent.
723 * Bits 22-0 (the bits that are selected by the mask
724 * {@code 0x007fffff}) represent the significand (sometimes called
725 * the mantissa) of the floating-point number.
726 *
727 * <p>If the argument is positive infinity, the result is
728 * {@code 0x7f800000}.
729 *
730 * <p>If the argument is negative infinity, the result is
731 * {@code 0xff800000}.
732 *
733 * <p>If the argument is NaN, the result is {@code 0x7fc00000}.
734 *
735 * <p>In all cases, the result is an integer that, when given to the
736 * {@link #intBitsToFloat(int)} method, will produce a floating-point
737 * value the same as the argument to {@code floatToIntBits}
738 * (except all NaN values are collapsed to a single
739 * "canonical" NaN value).
740 *
741 * @param value a floating-point number.
742 * @return the bits that represent the floating-point number.
743 */
744 @HotSpotIntrinsicCandidate
745 public static int floatToIntBits(float value) {
746 if (!isNaN(value)) {
747 return floatToRawIntBits(value);
748 }
749 return 0x7fc00000;
750 }
751
752 /**
753 * Returns a representation of the specified floating-point value
754 * according to the IEEE 754 floating-point "single format" bit
755 * layout, preserving Not-a-Number (NaN) values.
756 *
757 * <p>Bit 31 (the bit that is selected by the mask
758 * {@code 0x80000000}) represents the sign of the floating-point
759 * number.
760 * Bits 30-23 (the bits that are selected by the mask
761 * {@code 0x7f800000}) represent the exponent.
762 * Bits 22-0 (the bits that are selected by the mask
763 * {@code 0x007fffff}) represent the significand (sometimes called
764 * the mantissa) of the floating-point number.
765 *
766 * <p>If the argument is positive infinity, the result is
767 * {@code 0x7f800000}.
768 *
769 * <p>If the argument is negative infinity, the result is
770 * {@code 0xff800000}.
771 *
772 * <p>If the argument is NaN, the result is the integer representing
773 * the actual NaN value. Unlike the {@code floatToIntBits}
774 * method, {@code floatToRawIntBits} does not collapse all the
775 * bit patterns encoding a NaN to a single "canonical"
776 * NaN value.
777 *
778 * <p>In all cases, the result is an integer that, when given to the
779 * {@link #intBitsToFloat(int)} method, will produce a
780 * floating-point value the same as the argument to
781 * {@code floatToRawIntBits}.
782 *
783 * @param value a floating-point number.
784 * @return the bits that represent the floating-point number.
785 * @since 1.3
786 */
787 @HotSpotIntrinsicCandidate
788 public static native int floatToRawIntBits(float value);
789
790 /**
791 * Returns the {@code float} value corresponding to a given
792 * bit representation.
793 * The argument is considered to be a representation of a
794 * floating-point value according to the IEEE 754 floating-point
795 * "single format" bit layout.
796 *
797 * <p>If the argument is {@code 0x7f800000}, the result is positive
798 * infinity.
799 *
800 * <p>If the argument is {@code 0xff800000}, the result is negative
801 * infinity.
802 *
803 * <p>If the argument is any value in the range
804 * {@code 0x7f800001} through {@code 0x7fffffff} or in
805 * the range {@code 0xff800001} through
806 * {@code 0xffffffff}, the result is a NaN. No IEEE 754
807 * floating-point operation provided by Java can distinguish
808 * between two NaN values of the same type with different bit
809 * patterns. Distinct values of NaN are only distinguishable by
810 * use of the {@code Float.floatToRawIntBits} method.
811 *
812 * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
813 * values that can be computed from the argument:
814 *
815 * <blockquote><pre>{@code
816 * int s = ((bits >> 31) == 0) ? 1 : -1;
817 * int e = ((bits >> 23) & 0xff);
818 * int m = (e == 0) ?
819 * (bits & 0x7fffff) << 1 :
820 * (bits & 0x7fffff) | 0x800000;
821 * }</pre></blockquote>
822 *
823 * Then the floating-point result equals the value of the mathematical
824 * expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-150</sup>.
825 *
826 * <p>Note that this method may not be able to return a
827 * {@code float} NaN with exactly same bit pattern as the
828 * {@code int} argument. IEEE 754 distinguishes between two
829 * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The
830 * differences between the two kinds of NaN are generally not
831 * visible in Java. Arithmetic operations on signaling NaNs turn
832 * them into quiet NaNs with a different, but often similar, bit
833 * pattern. However, on some processors merely copying a
834 * signaling NaN also performs that conversion. In particular,
835 * copying a signaling NaN to return it to the calling method may
836 * perform this conversion. So {@code intBitsToFloat} may
837 * not be able to return a {@code float} with a signaling NaN
838 * bit pattern. Consequently, for some {@code int} values,
839 * {@code floatToRawIntBits(intBitsToFloat(start))} may
840 * <i>not</i> equal {@code start}. Moreover, which
841 * particular bit patterns represent signaling NaNs is platform
842 * dependent; although all NaN bit patterns, quiet or signaling,
843 * must be in the NaN range identified above.
844 *
845 * @param bits an integer.
846 * @return the {@code float} floating-point value with the same bit
847 * pattern.
848 */
849 @HotSpotIntrinsicCandidate
850 public static native float intBitsToFloat(int bits);
851
852 /**
853 * Compares two {@code Float} objects numerically. There are
854 * two ways in which comparisons performed by this method differ
855 * from those performed by the Java language numerical comparison
856 * operators ({@code <, <=, ==, >=, >}) when
857 * applied to primitive {@code float} values:
858 *
859 * <ul><li>
860 * {@code Float.NaN} is considered by this method to
861 * be equal to itself and greater than all other
862 * {@code float} values
863 * (including {@code Float.POSITIVE_INFINITY}).
864 * <li>
865 * {@code 0.0f} is considered by this method to be greater
866 * than {@code -0.0f}.
867 * </ul>
868 *
869 * This ensures that the <i>natural ordering</i> of {@code Float}
870 * objects imposed by this method is <i>consistent with equals</i>.
871 *
872 * @param anotherFloat the {@code Float} to be compared.
873 * @return the value {@code 0} if {@code anotherFloat} is
874 * numerically equal to this {@code Float}; a value
875 * less than {@code 0} if this {@code Float}
876 * is numerically less than {@code anotherFloat};
877 * and a value greater than {@code 0} if this
878 * {@code Float} is numerically greater than
879 * {@code anotherFloat}.
880 *
881 * @since 1.2
882 * @see Comparable#compareTo(Object)
883 */
884 public int compareTo(Float anotherFloat) {
885 return Float.compare(value, anotherFloat.value);
886 }
887
888 /**
889 * Compares the two specified {@code float} values. The sign
890 * of the integer value returned is the same as that of the
891 * integer that would be returned by the call:
892 * <pre>
893 * new Float(f1).compareTo(new Float(f2))
894 * </pre>
895 *
896 * @param f1 the first {@code float} to compare.
897 * @param f2 the second {@code float} to compare.
898 * @return the value {@code 0} if {@code f1} is
899 * numerically equal to {@code f2}; a value less than
900 * {@code 0} if {@code f1} is numerically less than
901 * {@code f2}; and a value greater than {@code 0}
902 * if {@code f1} is numerically greater than
903 * {@code f2}.
904 * @since 1.4
905 */
906 public static int compare(float f1, float f2) {
907 if (f1 < f2)
908 return -1; // Neither val is NaN, thisVal is smaller
909 if (f1 > f2)
910 return 1; // Neither val is NaN, thisVal is larger
911
912 // Cannot use floatToRawIntBits because of possibility of NaNs.
913 int thisBits = Float.floatToIntBits(f1);
914 int anotherBits = Float.floatToIntBits(f2);
915
916 return (thisBits == anotherBits ? 0 : // Values are equal
917 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
918 1)); // (0.0, -0.0) or (NaN, !NaN)
919 }
920
921 /**
922 * Adds two {@code float} values together as per the + operator.
923 *
924 * @param a the first operand
925 * @param b the second operand
926 * @return the sum of {@code a} and {@code b}
927 * @jls 4.2.4 Floating-Point Operations
928 * @see java.util.function.BinaryOperator
929 * @since 1.8
930 */
931 public static float sum(float a, float b) {
932 return a + b;
933 }
934
935 /**
936 * Returns the greater of two {@code float} values
937 * as if by calling {@link Math#max(float, float) Math.max}.
938 *
939 * @param a the first operand
940 * @param b the second operand
941 * @return the greater of {@code a} and {@code b}
942 * @see java.util.function.BinaryOperator
943 * @since 1.8
944 */
945 public static float max(float a, float b) {
946 return Math.max(a, b);
947 }
948
949 /**
950 * Returns the smaller of two {@code float} values
951 * as if by calling {@link Math#min(float, float) Math.min}.
952 *
953 * @param a the first operand
954 * @param b the second operand
955 * @return the smaller of {@code a} and {@code b}
956 * @see java.util.function.BinaryOperator
957 * @since 1.8
958 */
959 public static float min(float a, float b) {
960 return Math.min(a, b);
961 }
962
963 /** use serialVersionUID from JDK 1.0.2 for interoperability */
964 private static final long serialVersionUID = -2671257302660747028L;
965 }