1 /*
2 * Copyright (c) 1994, 2013, 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 sun.misc.FloatingDecimal;
29 import sun.misc.FloatConsts;
30 import sun.misc.DoubleConsts;
31 import jdk.internal.HotSpotIntrinsicCandidate;
32
33 /**
34 * The {@code Float} class wraps a value of primitive type
35 * {@code float} in an object. An object of type
36 * {@code Float} contains a single field whose type is
37 * {@code float}.
38 *
39 * <p>In addition, this class provides several methods for converting a
40 * {@code float} to a {@code String} and a
41 * {@code String} to a {@code float}, as well as other
42 * constants and methods useful when dealing with a
43 * {@code float}.
44 *
45 * @author Lee Boynton
46 * @author Arthur van Hoff
47 * @author Joseph D. Darcy
48 * @since 1.0
49 */
50 public final class Float extends Number implements Comparable<Float> {
51 /**
52 * A constant holding the positive infinity of type
53 * {@code float}. It is equal to the value returned by
54 * {@code Float.intBitsToFloat(0x7f800000)}.
55 */
56 public static final float POSITIVE_INFINITY = 1.0f / 0.0f;
57
58 /**
59 * A constant holding the negative infinity of type
60 * {@code float}. It is equal to the value returned by
61 * {@code Float.intBitsToFloat(0xff800000)}.
62 */
63 public static final float NEGATIVE_INFINITY = -1.0f / 0.0f;
64
65 /**
66 * A constant holding a Not-a-Number (NaN) value of type
67 * {@code float}. It is equivalent to the value returned by
68 * {@code Float.intBitsToFloat(0x7fc00000)}.
69 */
70 public static final float NaN = 0.0f / 0.0f;
71
72 /**
73 * A constant holding the largest positive finite value of type
74 * {@code float}, (2-2<sup>-23</sup>)·2<sup>127</sup>.
75 * It is equal to the hexadecimal floating-point literal
76 * {@code 0x1.fffffeP+127f} and also equal to
77 * {@code Float.intBitsToFloat(0x7f7fffff)}.
78 */
79 public static final float MAX_VALUE = 0x1.fffffeP+127f; // 3.4028235e+38f
80
81 /**
82 * A constant holding the smallest positive normal value of type
83 * {@code float}, 2<sup>-126</sup>. It is equal to the
84 * hexadecimal floating-point literal {@code 0x1.0p-126f} and also
85 * equal to {@code Float.intBitsToFloat(0x00800000)}.
86 *
87 * @since 1.6
88 */
89 public static final float MIN_NORMAL = 0x1.0p-126f; // 1.17549435E-38f
90
91 /**
92 * A constant holding the smallest positive nonzero value of type
93 * {@code float}, 2<sup>-149</sup>. It is equal to the
94 * hexadecimal floating-point literal {@code 0x0.000002P-126f}
95 * and also equal to {@code Float.intBitsToFloat(0x1)}.
96 */
97 public static final float MIN_VALUE = 0x0.000002P-126f; // 1.4e-45f
98
99 /**
100 * Maximum exponent a finite {@code float} variable may have. It
101 * is equal to the value returned by {@code
102 * Math.getExponent(Float.MAX_VALUE)}.
103 *
104 * @since 1.6
105 */
106 public static final int MAX_EXPONENT = 127;
107
108 /**
109 * Minimum exponent a normalized {@code float} variable may have.
110 * It is equal to the value returned by {@code
111 * Math.getExponent(Float.MIN_NORMAL)}.
112 *
113 * @since 1.6
114 */
115 public static final int MIN_EXPONENT = -126;
116
117 /**
118 * The number of bits used to represent a {@code float} value.
119 *
120 * @since 1.5
121 */
122 public static final int SIZE = 32;
123
124 /**
125 * The number of bytes used to represent a {@code float} value.
126 *
127 * @since 1.8
128 */
129 public static final int BYTES = SIZE / Byte.SIZE;
130
131 /**
132 * The {@code Class} instance representing the primitive type
133 * {@code float}.
134 *
135 * @since 1.1
136 */
137 @SuppressWarnings("unchecked")
138 public static final Class<Float> TYPE = (Class<Float>) Class.getPrimitiveClass("float");
139
140 /**
141 * Returns a string representation of the {@code float}
142 * argument. All characters mentioned below are ASCII characters.
143 * <ul>
144 * <li>If the argument is NaN, the result is the string
145 * "{@code NaN}".
146 * <li>Otherwise, the result is a string that represents the sign and
147 * magnitude (absolute value) of the argument. If the sign is
148 * negative, the first character of the result is
149 * '{@code -}' ({@code '\u005Cu002D'}); if the sign is
150 * positive, no sign character appears in the result. As for
151 * the magnitude <i>m</i>:
152 * <ul>
153 * <li>If <i>m</i> is infinity, it is represented by the characters
154 * {@code "Infinity"}; thus, positive infinity produces
155 * the result {@code "Infinity"} and negative infinity
156 * produces the result {@code "-Infinity"}.
157 * <li>If <i>m</i> is zero, it is represented by the characters
158 * {@code "0.0"}; thus, negative zero produces the result
159 * {@code "-0.0"} and positive zero produces the result
160 * {@code "0.0"}.
161 * <li> If <i>m</i> is greater than or equal to 10<sup>-3</sup> but
162 * less than 10<sup>7</sup>, then it is represented as the
163 * integer part of <i>m</i>, in decimal form with no leading
164 * zeroes, followed by '{@code .}'
165 * ({@code '\u005Cu002E'}), followed by one or more
166 * decimal digits representing the fractional part of
167 * <i>m</i>.
168 * <li> If <i>m</i> is less than 10<sup>-3</sup> or greater than or
169 * equal to 10<sup>7</sup>, then it is represented in
170 * so-called "computerized scientific notation." Let <i>n</i>
171 * be the unique integer such that 10<sup><i>n</i> </sup>≤
172 * <i>m</i> {@literal <} 10<sup><i>n</i>+1</sup>; then let <i>a</i>
173 * be the mathematically exact quotient of <i>m</i> and
174 * 10<sup><i>n</i></sup> so that 1 ≤ <i>a</i> {@literal <} 10.
175 * The magnitude is then represented as the integer part of
176 * <i>a</i>, as a single decimal digit, followed by
177 * '{@code .}' ({@code '\u005Cu002E'}), followed by
178 * decimal digits representing the fractional part of
179 * <i>a</i>, followed by the letter '{@code E}'
180 * ({@code '\u005Cu0045'}), followed by a representation
181 * of <i>n</i> as a decimal integer, as produced by the
182 * method {@link java.lang.Integer#toString(int)}.
183 *
184 * </ul>
185 * </ul>
186 * How many digits must be printed for the fractional part of
187 * <i>m</i> or <i>a</i>? There must be at least one digit
188 * to represent the fractional part, and beyond that as many, but
189 * only as many, more digits as are needed to uniquely distinguish
190 * the argument value from adjacent values of type
191 * {@code float}. That is, suppose that <i>x</i> is the
192 * exact mathematical value represented by the decimal
193 * representation produced by this method for a finite nonzero
194 * argument <i>f</i>. Then <i>f</i> must be the {@code float}
195 * value nearest to <i>x</i>; or, if two {@code float} values are
196 * equally close to <i>x</i>, then <i>f</i> must be one of
197 * them and the least significant bit of the significand of
198 * <i>f</i> must be {@code 0}.
199 *
200 * <p>To create localized string representations of a floating-point
201 * value, use subclasses of {@link java.text.NumberFormat}.
202 *
203 * @param f the float to be converted.
204 * @return a string representation of the argument.
205 */
206 public static String toString(float f) {
207 return FloatingDecimal.toJavaFormatString(f);
208 }
209
210 /**
211 * Returns a hexadecimal string representation of the
212 * {@code float} argument. All characters mentioned below are
213 * ASCII characters.
214 *
215 * <ul>
216 * <li>If the argument is NaN, the result is the string
217 * "{@code NaN}".
218 * <li>Otherwise, the result is a string that represents the sign and
219 * magnitude (absolute value) of the argument. If the sign is negative,
220 * the first character of the result is '{@code -}'
221 * ({@code '\u005Cu002D'}); if the sign is positive, no sign character
222 * appears in the result. As for the magnitude <i>m</i>:
223 *
224 * <ul>
225 * <li>If <i>m</i> is infinity, it is represented by the string
226 * {@code "Infinity"}; thus, positive infinity produces the
227 * result {@code "Infinity"} and negative infinity produces
228 * the result {@code "-Infinity"}.
229 *
230 * <li>If <i>m</i> is zero, it is represented by the string
231 * {@code "0x0.0p0"}; thus, negative zero produces the result
232 * {@code "-0x0.0p0"} and positive zero produces the result
233 * {@code "0x0.0p0"}.
234 *
235 * <li>If <i>m</i> is a {@code float} value with a
236 * normalized representation, substrings are used to represent the
237 * significand and exponent fields. The significand is
238 * represented by the characters {@code "0x1."}
239 * followed by a lowercase hexadecimal representation of the rest
240 * of the significand as a fraction. Trailing zeros in the
241 * hexadecimal representation are removed unless all the digits
242 * are zero, in which case a single zero is used. Next, the
243 * exponent is represented by {@code "p"} followed
244 * by a decimal string of the unbiased exponent as if produced by
245 * a call to {@link Integer#toString(int) Integer.toString} on the
246 * exponent value.
247 *
248 * <li>If <i>m</i> is a {@code float} value with a subnormal
249 * representation, the significand is represented by the
250 * characters {@code "0x0."} followed by a
251 * hexadecimal representation of the rest of the significand as a
252 * fraction. Trailing zeros in the hexadecimal representation are
253 * removed. Next, the exponent is represented by
254 * {@code "p-126"}. Note that there must be at
255 * least one nonzero digit in a subnormal significand.
256 *
257 * </ul>
258 *
259 * </ul>
260 *
261 * <table border>
262 * <caption>Examples</caption>
263 * <tr><th>Floating-point Value</th><th>Hexadecimal String</th>
264 * <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td>
265 * <tr><td>{@code -1.0}</td> <td>{@code -0x1.0p0}</td>
266 * <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td>
267 * <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td>
268 * <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td>
269 * <tr><td>{@code 0.25}</td> <td>{@code 0x1.0p-2}</td>
270 * <tr><td>{@code Float.MAX_VALUE}</td>
271 * <td>{@code 0x1.fffffep127}</td>
272 * <tr><td>{@code Minimum Normal Value}</td>
273 * <td>{@code 0x1.0p-126}</td>
274 * <tr><td>{@code Maximum Subnormal Value}</td>
275 * <td>{@code 0x0.fffffep-126}</td>
276 * <tr><td>{@code Float.MIN_VALUE}</td>
277 * <td>{@code 0x0.000002p-126}</td>
278 * </table>
279 * @param f the {@code float} to be converted.
280 * @return a hex string representation of the argument.
281 * @since 1.5
282 * @author Joseph D. Darcy
283 */
284 public static String toHexString(float f) {
285 if (Math.abs(f) < FloatConsts.MIN_NORMAL
286 && f != 0.0f ) {// float subnormal
287 // Adjust exponent to create subnormal double, then
288 // replace subnormal double exponent with subnormal float
289 // exponent
290 String s = Double.toHexString(Math.scalb((double)f,
291 /* -1022+126 */
292 DoubleConsts.MIN_EXPONENT-
293 FloatConsts.MIN_EXPONENT));
294 return s.replaceFirst("p-1022$", "p-126");
295 }
296 else // double string will be the same as float string
297 return Double.toHexString(f);
298 }
299
300 /**
301 * Returns a {@code Float} object holding the
302 * {@code float} value represented by the argument string
303 * {@code s}.
304 *
305 * <p>If {@code s} is {@code null}, then a
306 * {@code NullPointerException} is thrown.
307 *
308 * <p>Leading and trailing whitespace characters in {@code s}
309 * are ignored. Whitespace is removed as if by the {@link
310 * String#trim} method; that is, both ASCII space and control
311 * characters are removed. The rest of {@code s} should
312 * constitute a <i>FloatValue</i> as described by the lexical
313 * syntax rules:
314 *
315 * <blockquote>
316 * <dl>
317 * <dt><i>FloatValue:</i>
318 * <dd><i>Sign<sub>opt</sub></i> {@code NaN}
319 * <dd><i>Sign<sub>opt</sub></i> {@code Infinity}
320 * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
321 * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
322 * <dd><i>SignedInteger</i>
323 * </dl>
324 *
325 * <dl>
326 * <dt><i>HexFloatingPointLiteral</i>:
327 * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
328 * </dl>
329 *
330 * <dl>
331 * <dt><i>HexSignificand:</i>
332 * <dd><i>HexNumeral</i>
333 * <dd><i>HexNumeral</i> {@code .}
334 * <dd>{@code 0x} <i>HexDigits<sub>opt</sub>
335 * </i>{@code .}<i> HexDigits</i>
336 * <dd>{@code 0X}<i> HexDigits<sub>opt</sub>
337 * </i>{@code .} <i>HexDigits</i>
338 * </dl>
339 *
340 * <dl>
341 * <dt><i>BinaryExponent:</i>
342 * <dd><i>BinaryExponentIndicator SignedInteger</i>
343 * </dl>
344 *
345 * <dl>
346 * <dt><i>BinaryExponentIndicator:</i>
347 * <dd>{@code p}
348 * <dd>{@code P}
349 * </dl>
350 *
351 * </blockquote>
352 *
353 * where <i>Sign</i>, <i>FloatingPointLiteral</i>,
354 * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
355 * <i>FloatTypeSuffix</i> are as defined in the lexical structure
356 * sections of
357 * <cite>The Java™ Language Specification</cite>,
358 * except that underscores are not accepted between digits.
359 * If {@code s} does not have the form of
360 * a <i>FloatValue</i>, then a {@code NumberFormatException}
361 * is thrown. Otherwise, {@code s} is regarded as
362 * representing an exact decimal value in the usual
363 * "computerized scientific notation" or as an exact
364 * hexadecimal value; this exact numerical value is then
365 * conceptually converted to an "infinitely precise"
366 * binary value that is then rounded to type {@code float}
367 * by the usual round-to-nearest rule of IEEE 754 floating-point
368 * arithmetic, which includes preserving the sign of a zero
369 * value.
370 *
371 * Note that the round-to-nearest rule also implies overflow and
372 * underflow behaviour; if the exact value of {@code s} is large
373 * enough in magnitude (greater than or equal to ({@link
374 * #MAX_VALUE} + {@link Math#ulp(float) ulp(MAX_VALUE)}/2),
375 * rounding to {@code float} will result in an infinity and if the
376 * exact value of {@code s} is small enough in magnitude (less
377 * than or equal to {@link #MIN_VALUE}/2), rounding to float will
378 * result in a zero.
379 *
380 * Finally, after rounding a {@code Float} object representing
381 * this {@code float} value is returned.
382 *
383 * <p>To interpret localized string representations of a
384 * floating-point value, use subclasses of {@link
385 * java.text.NumberFormat}.
386 *
387 * <p>Note that trailing format specifiers, specifiers that
388 * determine the type of a floating-point literal
389 * ({@code 1.0f} is a {@code float} value;
390 * {@code 1.0d} is a {@code double} value), do
391 * <em>not</em> influence the results of this method. In other
392 * words, the numerical value of the input string is converted
393 * directly to the target floating-point type. In general, the
394 * two-step sequence of conversions, string to {@code double}
395 * followed by {@code double} to {@code float}, is
396 * <em>not</em> equivalent to converting a string directly to
397 * {@code float}. For example, if first converted to an
398 * intermediate {@code double} and then to
399 * {@code float}, the string<br>
400 * {@code "1.00000017881393421514957253748434595763683319091796875001d"}<br>
401 * results in the {@code float} value
402 * {@code 1.0000002f}; if the string is converted directly to
403 * {@code float}, <code>1.000000<b>1</b>f</code> results.
404 *
405 * <p>To avoid calling this method on an invalid string and having
406 * a {@code NumberFormatException} be thrown, the documentation
407 * for {@link Double#valueOf Double.valueOf} lists a regular
408 * expression which can be used to screen the input.
409 *
410 * @param s the string to be parsed.
411 * @return a {@code Float} object holding the value
412 * represented by the {@code String} argument.
413 * @throws NumberFormatException if the string does not contain a
414 * parsable number.
415 */
416 public static Float valueOf(String s) throws NumberFormatException {
417 return new Float(parseFloat(s));
418 }
419
420 /**
421 * Returns a {@code Float} instance representing the specified
422 * {@code float} value.
423 * If a new {@code Float} instance is not required, this method
424 * should generally be used in preference to the constructor
425 * {@link #Float(float)}, as this method is likely to yield
426 * significantly better space and time performance by caching
427 * frequently requested values.
428 *
429 * @param f a float value.
430 * @return a {@code Float} instance representing {@code f}.
431 * @since 1.5
432 */
433 @HotSpotIntrinsicCandidate
434 public static Float valueOf(float f) {
435 return new Float(f);
436 }
437
438 /**
439 * Returns a new {@code float} initialized to the value
440 * represented by the specified {@code String}, as performed
441 * by the {@code valueOf} method of class {@code Float}.
442 *
443 * @param s the string to be parsed.
444 * @return the {@code float} value represented by the string
445 * argument.
446 * @throws NullPointerException if the string is null
447 * @throws NumberFormatException if the string does not contain a
448 * parsable {@code float}.
449 * @see java.lang.Float#valueOf(String)
450 * @since 1.2
451 */
452 public static float parseFloat(String s) throws NumberFormatException {
453 return FloatingDecimal.parseFloat(s);
454 }
455
456 /**
457 * Returns {@code true} if the specified number is a
458 * Not-a-Number (NaN) value, {@code false} otherwise.
459 *
460 * @param v the value to be tested.
461 * @return {@code true} if the argument is NaN;
462 * {@code false} otherwise.
463 */
464 public static boolean isNaN(float v) {
465 return (v != v);
466 }
467
468 /**
469 * Returns {@code true} if the specified number is infinitely
470 * large in magnitude, {@code false} otherwise.
471 *
472 * @param v the value to be tested.
473 * @return {@code true} if the argument is positive infinity or
474 * negative infinity; {@code false} otherwise.
475 */
476 public static boolean isInfinite(float v) {
477 return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
478 }
479
480
481 /**
482 * Returns {@code true} if the argument is a finite floating-point
483 * value; returns {@code false} otherwise (for NaN and infinity
484 * arguments).
485 *
486 * @param f the {@code float} value to be tested
487 * @return {@code true} if the argument is a finite
488 * floating-point value, {@code false} otherwise.
489 * @since 1.8
490 */
491 public static boolean isFinite(float f) {
492 return Math.abs(f) <= FloatConsts.MAX_VALUE;
493 }
494
495 /**
496 * The value of the Float.
497 *
498 * @serial
499 */
500 private final float value;
501
502 /**
503 * Constructs a newly allocated {@code Float} object that
504 * represents the primitive {@code float} argument.
505 *
506 * @param value the value to be represented by the {@code Float}.
507 */
508 public Float(float value) {
509 this.value = value;
510 }
511
512 /**
513 * Constructs a newly allocated {@code Float} object that
514 * represents the argument converted to type {@code float}.
515 *
516 * @param value the value to be represented by the {@code Float}.
517 */
518 public Float(double value) {
519 this.value = (float)value;
520 }
521
522 /**
523 * Constructs a newly allocated {@code Float} object that
524 * represents the floating-point value of type {@code float}
525 * represented by the string. The string is converted to a
526 * {@code float} value as if by the {@code valueOf} method.
527 *
528 * @param s a string to be converted to a {@code Float}.
529 * @throws NumberFormatException if the string does not contain a
530 * parsable number.
531 * @see java.lang.Float#valueOf(java.lang.String)
532 */
533 public Float(String s) throws NumberFormatException {
534 value = parseFloat(s);
535 }
536
537 /**
538 * Returns {@code true} if this {@code Float} value is a
539 * Not-a-Number (NaN), {@code false} otherwise.
540 *
541 * @return {@code true} if the value represented by this object is
542 * NaN; {@code false} otherwise.
543 */
544 public boolean isNaN() {
545 return isNaN(value);
546 }
547
548 /**
549 * Returns {@code true} if this {@code Float} value is
550 * infinitely large in magnitude, {@code false} otherwise.
551 *
552 * @return {@code true} if the value represented by this object is
553 * positive infinity or negative infinity;
554 * {@code false} otherwise.
555 */
556 public boolean isInfinite() {
557 return isInfinite(value);
558 }
559
560 /**
561 * Returns a string representation of this {@code Float} object.
562 * The primitive {@code float} value represented by this object
563 * is converted to a {@code String} exactly as if by the method
564 * {@code toString} of one argument.
565 *
566 * @return a {@code String} representation of this object.
567 * @see java.lang.Float#toString(float)
568 */
569 public String toString() {
570 return Float.toString(value);
571 }
572
573 /**
574 * Returns the value of this {@code Float} as a {@code byte} after
575 * a narrowing primitive conversion.
576 *
577 * @return the {@code float} value represented by this object
578 * converted to type {@code byte}
579 * @jls 5.1.3 Narrowing Primitive Conversions
580 */
581 public byte byteValue() {
582 return (byte)value;
583 }
584
585 /**
586 * Returns the value of this {@code Float} as a {@code short}
587 * after a narrowing primitive conversion.
588 *
589 * @return the {@code float} value represented by this object
590 * converted to type {@code short}
591 * @jls 5.1.3 Narrowing Primitive Conversions
592 * @since 1.1
593 */
594 public short shortValue() {
595 return (short)value;
596 }
597
598 /**
599 * Returns the value of this {@code Float} as an {@code int} after
600 * a narrowing primitive conversion.
601 *
602 * @return the {@code float} value represented by this object
603 * converted to type {@code int}
604 * @jls 5.1.3 Narrowing Primitive Conversions
605 */
606 public int intValue() {
607 return (int)value;
608 }
609
610 /**
611 * Returns value of this {@code Float} as a {@code long} after a
612 * narrowing primitive conversion.
613 *
614 * @return the {@code float} value represented by this object
615 * converted to type {@code long}
616 * @jls 5.1.3 Narrowing Primitive Conversions
617 */
618 public long longValue() {
619 return (long)value;
620 }
621
622 /**
623 * Returns the {@code float} value of this {@code Float} object.
624 *
625 * @return the {@code float} value represented by this object
626 */
627 @HotSpotIntrinsicCandidate
628 public float floatValue() {
629 return value;
630 }
631
632 /**
633 * Returns the value of this {@code Float} as a {@code double}
634 * after a widening primitive conversion.
635 *
636 * @return the {@code float} value represented by this
637 * object converted to type {@code double}
638 * @jls 5.1.2 Widening Primitive Conversions
639 */
640 public double doubleValue() {
641 return (double)value;
642 }
643
644 /**
645 * Returns a hash code for this {@code Float} object. The
646 * result is the integer bit representation, exactly as produced
647 * by the method {@link #floatToIntBits(float)}, of the primitive
648 * {@code float} value represented by this {@code Float}
649 * object.
650 *
651 * @return a hash code value for this object.
652 */
653 @Override
654 public int hashCode() {
655 return Float.hashCode(value);
656 }
657
658 /**
659 * Returns a hash code for a {@code float} value; compatible with
660 * {@code Float.hashCode()}.
661 *
662 * @param value the value to hash
663 * @return a hash code value for a {@code float} value.
664 * @since 1.8
665 */
666 public static int hashCode(float value) {
667 return floatToIntBits(value);
668 }
669
670 /**
671
672 * Compares this object against the specified object. The result
673 * is {@code true} if and only if the argument is not
674 * {@code null} and is a {@code Float} object that
675 * represents a {@code float} with the same value as the
676 * {@code float} represented by this object. For this
677 * purpose, two {@code float} values are considered to be the
678 * same if and only if the method {@link #floatToIntBits(float)}
679 * returns the identical {@code int} value when applied to
680 * each.
681 *
682 * <p>Note that in most cases, for two instances of class
683 * {@code Float}, {@code f1} and {@code f2}, the value
684 * of {@code f1.equals(f2)} is {@code true} if and only if
685 *
686 * <blockquote><pre>
687 * f1.floatValue() == f2.floatValue()
688 * </pre></blockquote>
689 *
690 * <p>also has the value {@code true}. However, there are two exceptions:
691 * <ul>
692 * <li>If {@code f1} and {@code f2} both represent
693 * {@code Float.NaN}, then the {@code equals} method returns
694 * {@code true}, even though {@code Float.NaN==Float.NaN}
695 * has the value {@code false}.
696 * <li>If {@code f1} represents {@code +0.0f} while
697 * {@code f2} represents {@code -0.0f}, or vice
698 * versa, the {@code equal} test has the value
699 * {@code false}, even though {@code 0.0f==-0.0f}
700 * has the value {@code true}.
701 * </ul>
702 *
703 * This definition allows hash tables to operate properly.
704 *
705 * @param obj the object to be compared
706 * @return {@code true} if the objects are the same;
707 * {@code false} otherwise.
708 * @see java.lang.Float#floatToIntBits(float)
709 */
710 public boolean equals(Object obj) {
711 return (obj instanceof Float)
712 && (floatToIntBits(((Float)obj).value) == floatToIntBits(value));
713 }
714
715 /**
716 * Returns a representation of the specified floating-point value
717 * according to the IEEE 754 floating-point "single format" bit
718 * layout.
719 *
720 * <p>Bit 31 (the bit that is selected by the mask
721 * {@code 0x80000000}) represents the sign of the floating-point
722 * number.
723 * Bits 30-23 (the bits that are selected by the mask
724 * {@code 0x7f800000}) represent the exponent.
725 * Bits 22-0 (the bits that are selected by the mask
726 * {@code 0x007fffff}) represent the significand (sometimes called
727 * the mantissa) of the floating-point number.
728 *
729 * <p>If the argument is positive infinity, the result is
730 * {@code 0x7f800000}.
731 *
732 * <p>If the argument is negative infinity, the result is
733 * {@code 0xff800000}.
734 *
735 * <p>If the argument is NaN, the result is {@code 0x7fc00000}.
736 *
737 * <p>In all cases, the result is an integer that, when given to the
738 * {@link #intBitsToFloat(int)} method, will produce a floating-point
739 * value the same as the argument to {@code floatToIntBits}
740 * (except all NaN values are collapsed to a single
741 * "canonical" NaN value).
742 *
743 * @param value a floating-point number.
744 * @return the bits that represent the floating-point number.
745 */
746 @HotSpotIntrinsicCandidate
747 public static int floatToIntBits(float value) {
748 if (!isNaN(value)) {
749 return floatToRawIntBits(value);
750 }
751 return 0x7fc00000;
752 }
753
754 /**
755 * Returns a representation of the specified floating-point value
756 * according to the IEEE 754 floating-point "single format" bit
757 * layout, preserving Not-a-Number (NaN) values.
758 *
759 * <p>Bit 31 (the bit that is selected by the mask
760 * {@code 0x80000000}) represents the sign of the floating-point
761 * number.
762 * Bits 30-23 (the bits that are selected by the mask
763 * {@code 0x7f800000}) represent the exponent.
764 * Bits 22-0 (the bits that are selected by the mask
765 * {@code 0x007fffff}) represent the significand (sometimes called
766 * the mantissa) of the floating-point number.
767 *
768 * <p>If the argument is positive infinity, the result is
769 * {@code 0x7f800000}.
770 *
771 * <p>If the argument is negative infinity, the result is
772 * {@code 0xff800000}.
773 *
774 * <p>If the argument is NaN, the result is the integer representing
775 * the actual NaN value. Unlike the {@code floatToIntBits}
776 * method, {@code floatToRawIntBits} does not collapse all the
777 * bit patterns encoding a NaN to a single "canonical"
778 * NaN value.
779 *
780 * <p>In all cases, the result is an integer that, when given to the
781 * {@link #intBitsToFloat(int)} method, will produce a
782 * floating-point value the same as the argument to
783 * {@code floatToRawIntBits}.
784 *
785 * @param value a floating-point number.
786 * @return the bits that represent the floating-point number.
787 * @since 1.3
788 */
789 @HotSpotIntrinsicCandidate
790 public static native int floatToRawIntBits(float value);
791
792 /**
793 * Returns the {@code float} value corresponding to a given
794 * bit representation.
795 * The argument is considered to be a representation of a
796 * floating-point value according to the IEEE 754 floating-point
797 * "single format" bit layout.
798 *
799 * <p>If the argument is {@code 0x7f800000}, the result is positive
800 * infinity.
801 *
802 * <p>If the argument is {@code 0xff800000}, the result is negative
803 * infinity.
804 *
805 * <p>If the argument is any value in the range
806 * {@code 0x7f800001} through {@code 0x7fffffff} or in
807 * the range {@code 0xff800001} through
808 * {@code 0xffffffff}, the result is a NaN. No IEEE 754
809 * floating-point operation provided by Java can distinguish
810 * between two NaN values of the same type with different bit
811 * patterns. Distinct values of NaN are only distinguishable by
812 * use of the {@code Float.floatToRawIntBits} method.
813 *
814 * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
815 * values that can be computed from the argument:
816 *
817 * <blockquote><pre>{@code
818 * int s = ((bits >> 31) == 0) ? 1 : -1;
819 * int e = ((bits >> 23) & 0xff);
820 * int m = (e == 0) ?
821 * (bits & 0x7fffff) << 1 :
822 * (bits & 0x7fffff) | 0x800000;
823 * }</pre></blockquote>
824 *
825 * Then the floating-point result equals the value of the mathematical
826 * expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-150</sup>.
827 *
828 * <p>Note that this method may not be able to return a
829 * {@code float} NaN with exactly same bit pattern as the
830 * {@code int} argument. IEEE 754 distinguishes between two
831 * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The
832 * differences between the two kinds of NaN are generally not
833 * visible in Java. Arithmetic operations on signaling NaNs turn
834 * them into quiet NaNs with a different, but often similar, bit
835 * pattern. However, on some processors merely copying a
836 * signaling NaN also performs that conversion. In particular,
837 * copying a signaling NaN to return it to the calling method may
838 * perform this conversion. So {@code intBitsToFloat} may
839 * not be able to return a {@code float} with a signaling NaN
840 * bit pattern. Consequently, for some {@code int} values,
841 * {@code floatToRawIntBits(intBitsToFloat(start))} may
842 * <i>not</i> equal {@code start}. Moreover, which
843 * particular bit patterns represent signaling NaNs is platform
844 * dependent; although all NaN bit patterns, quiet or signaling,
845 * must be in the NaN range identified above.
846 *
847 * @param bits an integer.
848 * @return the {@code float} floating-point value with the same bit
849 * pattern.
850 */
851 @HotSpotIntrinsicCandidate
852 public static native float intBitsToFloat(int bits);
853
854 /**
855 * Compares two {@code Float} objects numerically. There are
856 * two ways in which comparisons performed by this method differ
857 * from those performed by the Java language numerical comparison
858 * operators ({@code <, <=, ==, >=, >}) when
859 * applied to primitive {@code float} values:
860 *
861 * <ul><li>
862 * {@code Float.NaN} is considered by this method to
863 * be equal to itself and greater than all other
864 * {@code float} values
865 * (including {@code Float.POSITIVE_INFINITY}).
866 * <li>
867 * {@code 0.0f} is considered by this method to be greater
868 * than {@code -0.0f}.
869 * </ul>
870 *
871 * This ensures that the <i>natural ordering</i> of {@code Float}
872 * objects imposed by this method is <i>consistent with equals</i>.
873 *
874 * @param anotherFloat the {@code Float} to be compared.
875 * @return the value {@code 0} if {@code anotherFloat} is
876 * numerically equal to this {@code Float}; a value
877 * less than {@code 0} if this {@code Float}
878 * is numerically less than {@code anotherFloat};
879 * and a value greater than {@code 0} if this
880 * {@code Float} is numerically greater than
881 * {@code anotherFloat}.
882 *
883 * @since 1.2
884 * @see Comparable#compareTo(Object)
885 */
886 public int compareTo(Float anotherFloat) {
887 return Float.compare(value, anotherFloat.value);
888 }
889
890 /**
891 * Compares the two specified {@code float} values. The sign
892 * of the integer value returned is the same as that of the
893 * integer that would be returned by the call:
894 * <pre>
895 * new Float(f1).compareTo(new Float(f2))
896 * </pre>
897 *
898 * @param f1 the first {@code float} to compare.
899 * @param f2 the second {@code float} to compare.
900 * @return the value {@code 0} if {@code f1} is
901 * numerically equal to {@code f2}; a value less than
902 * {@code 0} if {@code f1} is numerically less than
903 * {@code f2}; and a value greater than {@code 0}
904 * if {@code f1} is numerically greater than
905 * {@code f2}.
906 * @since 1.4
907 */
908 public static int compare(float f1, float f2) {
909 if (f1 < f2)
910 return -1; // Neither val is NaN, thisVal is smaller
911 if (f1 > f2)
912 return 1; // Neither val is NaN, thisVal is larger
913
914 // Cannot use floatToRawIntBits because of possibility of NaNs.
915 int thisBits = Float.floatToIntBits(f1);
916 int anotherBits = Float.floatToIntBits(f2);
917
918 return (thisBits == anotherBits ? 0 : // Values are equal
919 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
920 1)); // (0.0, -0.0) or (NaN, !NaN)
921 }
922
923 /**
924 * Adds two {@code float} values together as per the + operator.
925 *
926 * @param a the first operand
927 * @param b the second operand
928 * @return the sum of {@code a} and {@code b}
929 * @jls 4.2.4 Floating-Point Operations
930 * @see java.util.function.BinaryOperator
931 * @since 1.8
932 */
933 public static float sum(float a, float b) {
934 return a + b;
935 }
936
937 /**
938 * Returns the greater of two {@code float} values
939 * as if by calling {@link Math#max(float, float) Math.max}.
940 *
941 * @param a the first operand
942 * @param b the second operand
943 * @return the greater of {@code a} and {@code b}
944 * @see java.util.function.BinaryOperator
945 * @since 1.8
946 */
947 public static float max(float a, float b) {
948 return Math.max(a, b);
949 }
950
951 /**
952 * Returns the smaller of two {@code float} values
953 * as if by calling {@link Math#min(float, float) Math.min}.
954 *
955 * @param a the first operand
956 * @param b the second operand
957 * @return the smaller of {@code a} and {@code b}
958 * @see java.util.function.BinaryOperator
959 * @since 1.8
960 */
961 public static float min(float a, float b) {
962 return Math.min(a, b);
963 }
964
965 /** use serialVersionUID from JDK 1.0.2 for interoperability */
966 private static final long serialVersionUID = -2671257302660747028L;
967 }