1 /*
2 * Copyright (c) 1994, 2019, 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 java.lang.invoke.MethodHandles;
29 import java.lang.constant.Constable;
30 import java.lang.constant.ConstantDesc;
31 import java.util.Optional;
32
33 import jdk.internal.math.FloatingDecimal;
34 import jdk.internal.HotSpotIntrinsicCandidate;
35
36 /**
37 * The {@code Float} class wraps a value of primitive type
38 * {@code float} in an object. An object of type
39 * {@code Float} contains a single field whose type is
40 * {@code float}.
41 *
42 * <p>In addition, this class provides several methods for converting a
43 * {@code float} to a {@code String} and a
44 * {@code String} to a {@code float}, as well as other
45 * constants and methods useful when dealing with a
46 * {@code float}.
47 *
48 * @author Lee Boynton
49 * @author Arthur van Hoff
50 * @author Joseph D. Darcy
51 * @since 1.0
52 */
53 public final class Float extends Number
54 implements Comparable<Float>, Constable, ConstantDesc {
55 /**
56 * A constant holding the positive infinity of type
57 * {@code float}. It is equal to the value returned by
58 * {@code Float.intBitsToFloat(0x7f800000)}.
59 */
60 public static final float POSITIVE_INFINITY = 1.0f / 0.0f;
61
62 /**
63 * A constant holding the negative infinity of type
64 * {@code float}. It is equal to the value returned by
65 * {@code Float.intBitsToFloat(0xff800000)}.
66 */
67 public static final float NEGATIVE_INFINITY = -1.0f / 0.0f;
68
69 /**
70 * A constant holding a Not-a-Number (NaN) value of type
71 * {@code float}. It is equivalent to the value returned by
72 * {@code Float.intBitsToFloat(0x7fc00000)}.
73 */
74 public static final float NaN = 0.0f / 0.0f;
75
76 /**
77 * A constant holding the largest positive finite value of type
78 * {@code float}, (2-2<sup>-23</sup>)·2<sup>127</sup>.
79 * It is equal to the hexadecimal floating-point literal
80 * {@code 0x1.fffffeP+127f} and also equal to
81 * {@code Float.intBitsToFloat(0x7f7fffff)}.
82 */
83 public static final float MAX_VALUE = 0x1.fffffeP+127f; // 3.4028235e+38f
84
85 /**
86 * A constant holding the smallest positive normal value of type
87 * {@code float}, 2<sup>-126</sup>. It is equal to the
88 * hexadecimal floating-point literal {@code 0x1.0p-126f} and also
89 * equal to {@code Float.intBitsToFloat(0x00800000)}.
90 *
91 * @since 1.6
92 */
93 public static final float MIN_NORMAL = 0x1.0p-126f; // 1.17549435E-38f
94
95 /**
96 * A constant holding the smallest positive nonzero value of type
97 * {@code float}, 2<sup>-149</sup>. It is equal to the
98 * hexadecimal floating-point literal {@code 0x0.000002P-126f}
99 * and also equal to {@code Float.intBitsToFloat(0x1)}.
100 */
101 public static final float MIN_VALUE = 0x0.000002P-126f; // 1.4e-45f
102
103 /**
104 * Maximum exponent a finite {@code float} variable may have. It
105 * is equal to the value returned by {@code
106 * Math.getExponent(Float.MAX_VALUE)}.
107 *
108 * @since 1.6
109 */
110 public static final int MAX_EXPONENT = 127;
111
112 /**
113 * Minimum exponent a normalized {@code float} variable may have.
114 * It is equal to the value returned by {@code
115 * Math.getExponent(Float.MIN_NORMAL)}.
116 *
117 * @since 1.6
118 */
119 public static final int MIN_EXPONENT = -126;
120
121 /**
122 * The number of bits used to represent a {@code float} value.
123 *
124 * @since 1.5
125 */
126 public static final int SIZE = 32;
127
128 /**
129 * The number of bytes used to represent a {@code float} value.
130 *
131 * @since 1.8
132 */
133 public static final int BYTES = SIZE / Byte.SIZE;
134
135 /**
136 * The {@code Class} instance representing the primitive type
137 * {@code float}.
138 *
139 * @since 1.1
140 */
141 @SuppressWarnings("unchecked")
142 public static final Class<Float> TYPE = (Class<Float>) Class.getPrimitiveClass("float");
143
144 /**
145 * Returns a string representation of the {@code float}
146 * argument. All characters mentioned below are ASCII characters.
147 * <ul>
148 * <li>If the argument is NaN, the result is the string
149 * "{@code NaN}".
150 * <li>Otherwise, the result is a string that represents the sign and
151 * magnitude (absolute value) of the argument. If the sign is
152 * negative, the first character of the result is
153 * '{@code -}' ({@code '\u005Cu002D'}); if the sign is
154 * positive, no sign character appears in the result. As for
155 * the magnitude <i>m</i>:
156 * <ul>
157 * <li>If <i>m</i> is infinity, it is represented by the characters
158 * {@code "Infinity"}; thus, positive infinity produces
159 * the result {@code "Infinity"} and negative infinity
160 * produces the result {@code "-Infinity"}.
161 * <li>If <i>m</i> is zero, it is represented by the characters
162 * {@code "0.0"}; thus, negative zero produces the result
163 * {@code "-0.0"} and positive zero produces the result
164 * {@code "0.0"}.
165 * <li> If <i>m</i> is greater than or equal to 10<sup>-3</sup> but
166 * less than 10<sup>7</sup>, then it is represented as the
167 * integer part of <i>m</i>, in decimal form with no leading
168 * zeroes, followed by '{@code .}'
169 * ({@code '\u005Cu002E'}), followed by one or more
170 * decimal digits representing the fractional part of
171 * <i>m</i>.
172 * <li> If <i>m</i> is less than 10<sup>-3</sup> or greater than or
173 * equal to 10<sup>7</sup>, then it is represented in
174 * so-called "computerized scientific notation." Let <i>n</i>
175 * be the unique integer such that 10<sup><i>n</i> </sup>≤
176 * <i>m</i> {@literal <} 10<sup><i>n</i>+1</sup>; then let <i>a</i>
177 * be the mathematically exact quotient of <i>m</i> and
178 * 10<sup><i>n</i></sup> so that 1 ≤ <i>a</i> {@literal <} 10.
179 * The magnitude is then represented as the integer part of
180 * <i>a</i>, as a single decimal digit, followed by
181 * '{@code .}' ({@code '\u005Cu002E'}), followed by
182 * decimal digits representing the fractional part of
183 * <i>a</i>, followed by the letter '{@code E}'
184 * ({@code '\u005Cu0045'}), followed by a representation
185 * of <i>n</i> as a decimal integer, as produced by the
186 * method {@link java.lang.Integer#toString(int)}.
187 *
188 * </ul>
189 * </ul>
190 * How many digits must be printed for the fractional part of
191 * <i>m</i> or <i>a</i>? There must be at least one digit
192 * to represent the fractional part, and beyond that as many, but
193 * only as many, more digits as are needed to uniquely distinguish
194 * the argument value from adjacent values of type
195 * {@code float}. That is, suppose that <i>x</i> is the
196 * exact mathematical value represented by the decimal
197 * representation produced by this method for a finite nonzero
198 * argument <i>f</i>. Then <i>f</i> must be the {@code float}
199 * value nearest to <i>x</i>; or, if two {@code float} values are
200 * equally close to <i>x</i>, then <i>f</i> must be one of
201 * them and the least significant bit of the significand of
202 * <i>f</i> must be {@code 0}.
203 *
204 * <p>To create localized string representations of a floating-point
205 * value, use subclasses of {@link java.text.NumberFormat}.
206 *
207 * @param f the float to be converted.
208 * @return a string representation of the argument.
209 */
210 public static String toString(float f) {
211 return FloatingDecimal.toJavaFormatString(f);
212 }
213
214 /**
215 * Returns a hexadecimal string representation of the
216 * {@code float} argument. All characters mentioned below are
217 * ASCII characters.
218 *
219 * <ul>
220 * <li>If the argument is NaN, the result is the string
221 * "{@code NaN}".
222 * <li>Otherwise, the result is a string that represents the sign and
223 * magnitude (absolute value) of the argument. If the sign is negative,
224 * the first character of the result is '{@code -}'
225 * ({@code '\u005Cu002D'}); if the sign is positive, no sign character
226 * appears in the result. As for the magnitude <i>m</i>:
227 *
228 * <ul>
229 * <li>If <i>m</i> is infinity, it is represented by the string
230 * {@code "Infinity"}; thus, positive infinity produces the
231 * result {@code "Infinity"} and negative infinity produces
232 * the result {@code "-Infinity"}.
233 *
234 * <li>If <i>m</i> is zero, it is represented by the string
235 * {@code "0x0.0p0"}; thus, negative zero produces the result
236 * {@code "-0x0.0p0"} and positive zero produces the result
237 * {@code "0x0.0p0"}.
238 *
239 * <li>If <i>m</i> is a {@code float} value with a
240 * normalized representation, substrings are used to represent the
241 * significand and exponent fields. The significand is
242 * represented by the characters {@code "0x1."}
243 * followed by a lowercase hexadecimal representation of the rest
244 * of the significand as a fraction. Trailing zeros in the
245 * hexadecimal representation are removed unless all the digits
246 * are zero, in which case a single zero is used. Next, the
247 * exponent is represented by {@code "p"} followed
248 * by a decimal string of the unbiased exponent as if produced by
249 * a call to {@link Integer#toString(int) Integer.toString} on the
250 * exponent value.
251 *
252 * <li>If <i>m</i> is a {@code float} value with a subnormal
253 * representation, the significand is represented by the
254 * characters {@code "0x0."} followed by a
255 * hexadecimal representation of the rest of the significand as a
256 * fraction. Trailing zeros in the hexadecimal representation are
257 * removed. Next, the exponent is represented by
258 * {@code "p-126"}. Note that there must be at
259 * least one nonzero digit in a subnormal significand.
260 *
261 * </ul>
262 *
263 * </ul>
264 *
265 * <table class="striped">
266 * <caption>Examples</caption>
267 * <thead>
268 * <tr><th scope="col">Floating-point Value</th><th scope="col">Hexadecimal String</th>
269 * </thead>
270 * <tbody>
271 * <tr><th scope="row">{@code 1.0}</th> <td>{@code 0x1.0p0}</td>
272 * <tr><th scope="row">{@code -1.0}</th> <td>{@code -0x1.0p0}</td>
273 * <tr><th scope="row">{@code 2.0}</th> <td>{@code 0x1.0p1}</td>
274 * <tr><th scope="row">{@code 3.0}</th> <td>{@code 0x1.8p1}</td>
275 * <tr><th scope="row">{@code 0.5}</th> <td>{@code 0x1.0p-1}</td>
276 * <tr><th scope="row">{@code 0.25}</th> <td>{@code 0x1.0p-2}</td>
277 * <tr><th scope="row">{@code Float.MAX_VALUE}</th>
278 * <td>{@code 0x1.fffffep127}</td>
279 * <tr><th scope="row">{@code Minimum Normal Value}</th>
280 * <td>{@code 0x1.0p-126}</td>
281 * <tr><th scope="row">{@code Maximum Subnormal Value}</th>
282 * <td>{@code 0x0.fffffep-126}</td>
283 * <tr><th scope="row">{@code Float.MIN_VALUE}</th>
284 * <td>{@code 0x0.000002p-126}</td>
285 * </tbody>
286 * </table>
287 * @param f the {@code float} to be converted.
288 * @return a hex string representation of the argument.
289 * @since 1.5
290 * @author Joseph D. Darcy
291 */
292 public static String toHexString(float f) {
293 if (Math.abs(f) < Float.MIN_NORMAL
294 && f != 0.0f ) {// float subnormal
295 // Adjust exponent to create subnormal double, then
296 // replace subnormal double exponent with subnormal float
297 // exponent
298 String s = Double.toHexString(Math.scalb((double)f,
299 /* -1022+126 */
300 Double.MIN_EXPONENT-
301 Float.MIN_EXPONENT));
302 return s.replaceFirst("p-1022$", "p-126");
303 }
304 else // double string will be the same as float string
305 return Double.toHexString(f);
306 }
307
308 /**
309 * Returns a {@code Float} object holding the
310 * {@code float} value represented by the argument string
311 * {@code s}.
312 *
313 * <p>If {@code s} is {@code null}, then a
314 * {@code NullPointerException} is thrown.
315 *
316 * <p>Leading and trailing whitespace characters in {@code s}
317 * are ignored. Whitespace is removed as if by the {@link
318 * String#trim} method; that is, both ASCII space and control
319 * characters are removed. The rest of {@code s} should
320 * constitute a <i>FloatValue</i> as described by the lexical
321 * syntax rules:
322 *
323 * <blockquote>
324 * <dl>
325 * <dt><i>FloatValue:</i>
326 * <dd><i>Sign<sub>opt</sub></i> {@code NaN}
327 * <dd><i>Sign<sub>opt</sub></i> {@code Infinity}
328 * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
329 * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
330 * <dd><i>SignedInteger</i>
331 * </dl>
332 *
333 * <dl>
334 * <dt><i>HexFloatingPointLiteral</i>:
335 * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
336 * </dl>
337 *
338 * <dl>
339 * <dt><i>HexSignificand:</i>
340 * <dd><i>HexNumeral</i>
341 * <dd><i>HexNumeral</i> {@code .}
342 * <dd>{@code 0x} <i>HexDigits<sub>opt</sub>
343 * </i>{@code .}<i> HexDigits</i>
344 * <dd>{@code 0X}<i> HexDigits<sub>opt</sub>
345 * </i>{@code .} <i>HexDigits</i>
346 * </dl>
347 *
348 * <dl>
349 * <dt><i>BinaryExponent:</i>
350 * <dd><i>BinaryExponentIndicator SignedInteger</i>
351 * </dl>
352 *
353 * <dl>
354 * <dt><i>BinaryExponentIndicator:</i>
355 * <dd>{@code p}
356 * <dd>{@code P}
357 * </dl>
358 *
359 * </blockquote>
360 *
361 * where <i>Sign</i>, <i>FloatingPointLiteral</i>,
362 * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
363 * <i>FloatTypeSuffix</i> are as defined in the lexical structure
364 * sections of
365 * <cite>The Java™ Language Specification</cite>,
366 * except that underscores are not accepted between digits.
367 * If {@code s} does not have the form of
368 * a <i>FloatValue</i>, then a {@code NumberFormatException}
369 * is thrown. Otherwise, {@code s} is regarded as
370 * representing an exact decimal value in the usual
371 * "computerized scientific notation" or as an exact
372 * hexadecimal value; this exact numerical value is then
373 * conceptually converted to an "infinitely precise"
374 * binary value that is then rounded to type {@code float}
375 * by the usual round-to-nearest rule of IEEE 754 floating-point
376 * arithmetic, which includes preserving the sign of a zero
377 * value.
378 *
379 * Note that the round-to-nearest rule also implies overflow and
380 * underflow behaviour; if the exact value of {@code s} is large
381 * enough in magnitude (greater than or equal to ({@link
382 * #MAX_VALUE} + {@link Math#ulp(float) ulp(MAX_VALUE)}/2),
383 * rounding to {@code float} will result in an infinity and if the
384 * exact value of {@code s} is small enough in magnitude (less
385 * than or equal to {@link #MIN_VALUE}/2), rounding to float will
386 * result in a zero.
387 *
388 * Finally, after rounding a {@code Float} object representing
389 * this {@code float} value is returned.
390 *
391 * <p>To interpret localized string representations of a
392 * floating-point value, use subclasses of {@link
393 * java.text.NumberFormat}.
394 *
395 * <p>Note that trailing format specifiers, specifiers that
396 * determine the type of a floating-point literal
397 * ({@code 1.0f} is a {@code float} value;
398 * {@code 1.0d} is a {@code double} value), do
399 * <em>not</em> influence the results of this method. In other
400 * words, the numerical value of the input string is converted
401 * directly to the target floating-point type. In general, the
402 * two-step sequence of conversions, string to {@code double}
403 * followed by {@code double} to {@code float}, is
404 * <em>not</em> equivalent to converting a string directly to
405 * {@code float}. For example, if first converted to an
406 * intermediate {@code double} and then to
407 * {@code float}, the string<br>
408 * {@code "1.00000017881393421514957253748434595763683319091796875001d"}<br>
409 * results in the {@code float} value
410 * {@code 1.0000002f}; if the string is converted directly to
411 * {@code float}, <code>1.000000<b>1</b>f</code> results.
412 *
413 * <p>To avoid calling this method on an invalid string and having
414 * a {@code NumberFormatException} be thrown, the documentation
415 * for {@link Double#valueOf Double.valueOf} lists a regular
416 * expression which can be used to screen the input.
417 *
418 * @param s the string to be parsed.
419 * @return a {@code Float} object holding the value
420 * represented by the {@code String} argument.
421 * @throws NumberFormatException if the string does not contain a
422 * parsable number.
423 */
424 public static Float valueOf(String s) throws NumberFormatException {
425 return new Float(parseFloat(s));
426 }
427
428 /**
429 * Returns a {@code Float} instance representing the specified
430 * {@code float} value.
431 * If a new {@code Float} instance is not required, this method
432 * should generally be used in preference to the constructor
433 * {@link #Float(float)}, as this method is likely to yield
434 * significantly better space and time performance by caching
435 * frequently requested values.
436 *
437 * @param f a float value.
438 * @return a {@code Float} instance representing {@code f}.
439 * @since 1.5
440 */
441 @HotSpotIntrinsicCandidate
442 public static Float valueOf(float f) {
443 return new Float(f);
444 }
445
446 /**
447 * Returns a new {@code float} initialized to the value
448 * represented by the specified {@code String}, as performed
449 * by the {@code valueOf} method of class {@code Float}.
450 *
451 * @param s the string to be parsed.
452 * @return the {@code float} value represented by the string
453 * argument.
454 * @throws NullPointerException if the string is null
455 * @throws NumberFormatException if the string does not contain a
456 * parsable {@code float}.
457 * @see java.lang.Float#valueOf(String)
458 * @since 1.2
459 */
460 public static float parseFloat(String s) throws NumberFormatException {
461 return FloatingDecimal.parseFloat(s);
462 }
463
464 /**
465 * Returns {@code true} if the specified number is a
466 * Not-a-Number (NaN) value, {@code false} otherwise.
467 *
468 * @param v the value to be tested.
469 * @return {@code true} if the argument is NaN;
470 * {@code false} otherwise.
471 */
472 public static boolean isNaN(float v) {
473 return (v != v);
474 }
475
476 /**
477 * Returns {@code true} if the specified number is infinitely
478 * large in magnitude, {@code false} otherwise.
479 *
480 * @param v the value to be tested.
481 * @return {@code true} if the argument is positive infinity or
482 * negative infinity; {@code false} otherwise.
483 */
484 public static boolean isInfinite(float v) {
485 return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
486 }
487
488
489 /**
490 * Returns {@code true} if the argument is a finite floating-point
491 * value; returns {@code false} otherwise (for NaN and infinity
492 * arguments).
493 *
494 * @param f the {@code float} value to be tested
495 * @return {@code true} if the argument is a finite
496 * floating-point value, {@code false} otherwise.
497 * @since 1.8
498 */
499 public static boolean isFinite(float f) {
500 return Math.abs(f) <= Float.MAX_VALUE;
501 }
502
503 /**
504 * The value of the Float.
505 *
506 * @serial
507 */
508 private final float value;
509
510 /**
511 * Constructs a newly allocated {@code Float} object that
512 * represents the primitive {@code float} argument.
513 *
514 * @param value the value to be represented by the {@code Float}.
515 *
516 * @deprecated
517 * It is rarely appropriate to use this constructor. The static factory
518 * {@link #valueOf(float)} is generally a better choice, as it is
519 * likely to yield significantly better space and time performance.
520 */
521 @Deprecated(since="9")
522 public Float(float value) {
523 this.value = value;
524 }
525
526 /**
527 * Constructs a newly allocated {@code Float} object that
528 * represents the argument converted to type {@code float}.
529 *
530 * @param value the value to be represented by the {@code Float}.
531 *
532 * @deprecated
533 * It is rarely appropriate to use this constructor. Instead, use the
534 * static factory method {@link #valueOf(float)} method as follows:
535 * {@code Float.valueOf((float)value)}.
536 */
537 @Deprecated(since="9")
538 public Float(double value) {
539 this.value = (float)value;
540 }
541
542 /**
543 * Constructs a newly allocated {@code Float} object that
544 * represents the floating-point value of type {@code float}
545 * represented by the string. The string is converted to a
546 * {@code float} value as if by the {@code valueOf} method.
547 *
548 * @param s a string to be converted to a {@code Float}.
549 * @throws NumberFormatException if the string does not contain a
550 * parsable number.
551 *
552 * @deprecated
553 * It is rarely appropriate to use this constructor.
554 * Use {@link #parseFloat(String)} to convert a string to a
555 * {@code float} primitive, or use {@link #valueOf(String)}
556 * to convert a string to a {@code Float} object.
557 */
558 @Deprecated(since="9")
559 public Float(String s) throws NumberFormatException {
560 value = parseFloat(s);
561 }
562
563 /**
564 * Returns {@code true} if this {@code Float} value is a
565 * Not-a-Number (NaN), {@code false} otherwise.
566 *
567 * @return {@code true} if the value represented by this object is
568 * NaN; {@code false} otherwise.
569 */
570 public boolean isNaN() {
571 return isNaN(value);
572 }
573
574 /**
575 * Returns {@code true} if this {@code Float} value is
576 * infinitely large in magnitude, {@code false} otherwise.
577 *
578 * @return {@code true} if the value represented by this object is
579 * positive infinity or negative infinity;
580 * {@code false} otherwise.
581 */
582 public boolean isInfinite() {
583 return isInfinite(value);
584 }
585
586 /**
587 * Returns a string representation of this {@code Float} object.
588 * The primitive {@code float} value represented by this object
589 * is converted to a {@code String} exactly as if by the method
590 * {@code toString} of one argument.
591 *
592 * @return a {@code String} representation of this object.
593 * @see java.lang.Float#toString(float)
594 */
595 public String toString() {
596 return Float.toString(value);
597 }
598
599 /**
600 * Returns the value of this {@code Float} as a {@code byte} after
601 * a narrowing primitive conversion.
602 *
603 * @return the {@code float} value represented by this object
604 * converted to type {@code byte}
605 * @jls 5.1.3 Narrowing Primitive Conversion
606 */
607 public byte byteValue() {
608 return (byte)value;
609 }
610
611 /**
612 * Returns the value of this {@code Float} as a {@code short}
613 * after a narrowing primitive conversion.
614 *
615 * @return the {@code float} value represented by this object
616 * converted to type {@code short}
617 * @jls 5.1.3 Narrowing Primitive Conversion
618 * @since 1.1
619 */
620 public short shortValue() {
621 return (short)value;
622 }
623
624 /**
625 * Returns the value of this {@code Float} as an {@code int} after
626 * a narrowing primitive conversion.
627 *
628 * @return the {@code float} value represented by this object
629 * converted to type {@code int}
630 * @jls 5.1.3 Narrowing Primitive Conversion
631 */
632 public int intValue() {
633 return (int)value;
634 }
635
636 /**
637 * Returns value of this {@code Float} as a {@code long} after a
638 * narrowing primitive conversion.
639 *
640 * @return the {@code float} value represented by this object
641 * converted to type {@code long}
642 * @jls 5.1.3 Narrowing Primitive Conversion
643 */
644 public long longValue() {
645 return (long)value;
646 }
647
648 /**
649 * Returns the {@code float} value of this {@code Float} object.
650 *
651 * @return the {@code float} value represented by this object
652 */
653 @HotSpotIntrinsicCandidate
654 public float floatValue() {
655 return value;
656 }
657
658 /**
659 * Returns the value of this {@code Float} as a {@code double}
660 * after a widening primitive conversion.
661 *
662 * @return the {@code float} value represented by this
663 * object converted to type {@code double}
664 * @jls 5.1.2 Widening Primitive Conversion
665 */
666 public double doubleValue() {
667 return (double)value;
668 }
669
670 /**
671 * Returns a hash code for this {@code Float} object. The
672 * result is the integer bit representation, exactly as produced
673 * by the method {@link #floatToIntBits(float)}, of the primitive
674 * {@code float} value represented by this {@code Float}
675 * object.
676 *
677 * @return a hash code value for this object.
678 */
679 @Override
680 public int hashCode() {
681 return Float.hashCode(value);
682 }
683
684 /**
685 * Returns a hash code for a {@code float} value; compatible with
686 * {@code Float.hashCode()}.
687 *
688 * @param value the value to hash
689 * @return a hash code value for a {@code float} value.
690 * @since 1.8
691 */
692 public static int hashCode(float value) {
693 return floatToIntBits(value);
694 }
695
696 /**
697
698 * Compares this object against the specified object. The result
699 * is {@code true} if and only if the argument is not
700 * {@code null} and is a {@code Float} object that
701 * represents a {@code float} with the same value as the
702 * {@code float} represented by this object. For this
703 * purpose, two {@code float} values are considered to be the
704 * same if and only if the method {@link #floatToIntBits(float)}
705 * returns the identical {@code int} value when applied to
706 * each.
707 *
708 * <p>Note that in most cases, for two instances of class
709 * {@code Float}, {@code f1} and {@code f2}, the value
710 * of {@code f1.equals(f2)} is {@code true} if and only if
711 *
712 * <blockquote><pre>
713 * f1.floatValue() == f2.floatValue()
714 * </pre></blockquote>
715 *
716 * <p>also has the value {@code true}. However, there are two exceptions:
717 * <ul>
718 * <li>If {@code f1} and {@code f2} both represent
719 * {@code Float.NaN}, then the {@code equals} method returns
720 * {@code true}, even though {@code Float.NaN==Float.NaN}
721 * has the value {@code false}.
722 * <li>If {@code f1} represents {@code +0.0f} while
723 * {@code f2} represents {@code -0.0f}, or vice
724 * versa, the {@code equal} test has the value
725 * {@code false}, even though {@code 0.0f==-0.0f}
726 * has the value {@code true}.
727 * </ul>
728 *
729 * This definition allows hash tables to operate properly.
730 *
731 * @param obj the object to be compared
732 * @return {@code true} if the objects are the same;
733 * {@code false} otherwise.
734 * @see java.lang.Float#floatToIntBits(float)
735 */
736 public boolean equals(Object obj) {
737 return (obj instanceof Float)
738 && (floatToIntBits(((Float)obj).value) == floatToIntBits(value));
739 }
740
741 /**
742 * Returns a representation of the specified floating-point value
743 * according to the IEEE 754 floating-point "single format" bit
744 * layout.
745 *
746 * <p>Bit 31 (the bit that is selected by the mask
747 * {@code 0x80000000}) represents the sign of the floating-point
748 * number.
749 * Bits 30-23 (the bits that are selected by the mask
750 * {@code 0x7f800000}) represent the exponent.
751 * Bits 22-0 (the bits that are selected by the mask
752 * {@code 0x007fffff}) represent the significand (sometimes called
753 * the mantissa) of the floating-point number.
754 *
755 * <p>If the argument is positive infinity, the result is
756 * {@code 0x7f800000}.
757 *
758 * <p>If the argument is negative infinity, the result is
759 * {@code 0xff800000}.
760 *
761 * <p>If the argument is NaN, the result is {@code 0x7fc00000}.
762 *
763 * <p>In all cases, the result is an integer that, when given to the
764 * {@link #intBitsToFloat(int)} method, will produce a floating-point
765 * value the same as the argument to {@code floatToIntBits}
766 * (except all NaN values are collapsed to a single
767 * "canonical" NaN value).
768 *
769 * @param value a floating-point number.
770 * @return the bits that represent the floating-point number.
771 */
772 @HotSpotIntrinsicCandidate
773 public static int floatToIntBits(float value) {
774 if (!isNaN(value)) {
775 return floatToRawIntBits(value);
776 }
777 return 0x7fc00000;
778 }
779
780 /**
781 * Returns a representation of the specified floating-point value
782 * according to the IEEE 754 floating-point "single format" bit
783 * layout, preserving Not-a-Number (NaN) values.
784 *
785 * <p>Bit 31 (the bit that is selected by the mask
786 * {@code 0x80000000}) represents the sign of the floating-point
787 * number.
788 * Bits 30-23 (the bits that are selected by the mask
789 * {@code 0x7f800000}) represent the exponent.
790 * Bits 22-0 (the bits that are selected by the mask
791 * {@code 0x007fffff}) represent the significand (sometimes called
792 * the mantissa) of the floating-point number.
793 *
794 * <p>If the argument is positive infinity, the result is
795 * {@code 0x7f800000}.
796 *
797 * <p>If the argument is negative infinity, the result is
798 * {@code 0xff800000}.
799 *
800 * <p>If the argument is NaN, the result is the integer representing
801 * the actual NaN value. Unlike the {@code floatToIntBits}
802 * method, {@code floatToRawIntBits} does not collapse all the
803 * bit patterns encoding a NaN to a single "canonical"
804 * NaN value.
805 *
806 * <p>In all cases, the result is an integer that, when given to the
807 * {@link #intBitsToFloat(int)} method, will produce a
808 * floating-point value the same as the argument to
809 * {@code floatToRawIntBits}.
810 *
811 * @param value a floating-point number.
812 * @return the bits that represent the floating-point number.
813 * @since 1.3
814 */
815 @HotSpotIntrinsicCandidate
816 public static native int floatToRawIntBits(float value);
817
818 /**
819 * Returns the {@code float} value corresponding to a given
820 * bit representation.
821 * The argument is considered to be a representation of a
822 * floating-point value according to the IEEE 754 floating-point
823 * "single format" bit layout.
824 *
825 * <p>If the argument is {@code 0x7f800000}, the result is positive
826 * infinity.
827 *
828 * <p>If the argument is {@code 0xff800000}, the result is negative
829 * infinity.
830 *
831 * <p>If the argument is any value in the range
832 * {@code 0x7f800001} through {@code 0x7fffffff} or in
833 * the range {@code 0xff800001} through
834 * {@code 0xffffffff}, the result is a NaN. No IEEE 754
835 * floating-point operation provided by Java can distinguish
836 * between two NaN values of the same type with different bit
837 * patterns. Distinct values of NaN are only distinguishable by
838 * use of the {@code Float.floatToRawIntBits} method.
839 *
840 * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
841 * values that can be computed from the argument:
842 *
843 * <blockquote><pre>{@code
844 * int s = ((bits >> 31) == 0) ? 1 : -1;
845 * int e = ((bits >> 23) & 0xff);
846 * int m = (e == 0) ?
847 * (bits & 0x7fffff) << 1 :
848 * (bits & 0x7fffff) | 0x800000;
849 * }</pre></blockquote>
850 *
851 * Then the floating-point result equals the value of the mathematical
852 * expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-150</sup>.
853 *
854 * <p>Note that this method may not be able to return a
855 * {@code float} NaN with exactly same bit pattern as the
856 * {@code int} argument. IEEE 754 distinguishes between two
857 * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The
858 * differences between the two kinds of NaN are generally not
859 * visible in Java. Arithmetic operations on signaling NaNs turn
860 * them into quiet NaNs with a different, but often similar, bit
861 * pattern. However, on some processors merely copying a
862 * signaling NaN also performs that conversion. In particular,
863 * copying a signaling NaN to return it to the calling method may
864 * perform this conversion. So {@code intBitsToFloat} may
865 * not be able to return a {@code float} with a signaling NaN
866 * bit pattern. Consequently, for some {@code int} values,
867 * {@code floatToRawIntBits(intBitsToFloat(start))} may
868 * <i>not</i> equal {@code start}. Moreover, which
869 * particular bit patterns represent signaling NaNs is platform
870 * dependent; although all NaN bit patterns, quiet or signaling,
871 * must be in the NaN range identified above.
872 *
873 * @param bits an integer.
874 * @return the {@code float} floating-point value with the same bit
875 * pattern.
876 */
877 @HotSpotIntrinsicCandidate
878 public static native float intBitsToFloat(int bits);
879
880 /**
881 * Compares two {@code Float} objects numerically. There are
882 * two ways in which comparisons performed by this method differ
883 * from those performed by the Java language numerical comparison
884 * operators ({@code <, <=, ==, >=, >}) when
885 * applied to primitive {@code float} values:
886 *
887 * <ul><li>
888 * {@code Float.NaN} is considered by this method to
889 * be equal to itself and greater than all other
890 * {@code float} values
891 * (including {@code Float.POSITIVE_INFINITY}).
892 * <li>
893 * {@code 0.0f} is considered by this method to be greater
894 * than {@code -0.0f}.
895 * </ul>
896 *
897 * This ensures that the <i>natural ordering</i> of {@code Float}
898 * objects imposed by this method is <i>consistent with equals</i>.
899 *
900 * @param anotherFloat the {@code Float} to be compared.
901 * @return the value {@code 0} if {@code anotherFloat} is
902 * numerically equal to this {@code Float}; a value
903 * less than {@code 0} if this {@code Float}
904 * is numerically less than {@code anotherFloat};
905 * and a value greater than {@code 0} if this
906 * {@code Float} is numerically greater than
907 * {@code anotherFloat}.
908 *
909 * @since 1.2
910 * @see Comparable#compareTo(Object)
911 */
912 public int compareTo(Float anotherFloat) {
913 return Float.compare(value, anotherFloat.value);
914 }
915
916 /**
917 * Compares the two specified {@code float} values. The sign
918 * of the integer value returned is the same as that of the
919 * integer that would be returned by the call:
920 * <pre>
921 * new Float(f1).compareTo(new Float(f2))
922 * </pre>
923 *
924 * @param f1 the first {@code float} to compare.
925 * @param f2 the second {@code float} to compare.
926 * @return the value {@code 0} if {@code f1} is
927 * numerically equal to {@code f2}; a value less than
928 * {@code 0} if {@code f1} is numerically less than
929 * {@code f2}; and a value greater than {@code 0}
930 * if {@code f1} is numerically greater than
931 * {@code f2}.
932 * @since 1.4
933 */
934 public static int compare(float f1, float f2) {
935 if (f1 < f2)
936 return -1; // Neither val is NaN, thisVal is smaller
937 if (f1 > f2)
938 return 1; // Neither val is NaN, thisVal is larger
939
940 // Cannot use floatToRawIntBits because of possibility of NaNs.
941 int thisBits = Float.floatToIntBits(f1);
942 int anotherBits = Float.floatToIntBits(f2);
943
944 return (thisBits == anotherBits ? 0 : // Values are equal
945 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
946 1)); // (0.0, -0.0) or (NaN, !NaN)
947 }
948
949 /**
950 * Adds two {@code float} values together as per the + operator.
951 *
952 * @param a the first operand
953 * @param b the second operand
954 * @return the sum of {@code a} and {@code b}
955 * @jls 4.2.4 Floating-Point Operations
956 * @see java.util.function.BinaryOperator
957 * @since 1.8
958 */
959 public static float sum(float a, float b) {
960 return a + b;
961 }
962
963 /**
964 * Returns the greater of two {@code float} values
965 * as if by calling {@link Math#max(float, float) Math.max}.
966 *
967 * @param a the first operand
968 * @param b the second operand
969 * @return the greater of {@code a} and {@code b}
970 * @see java.util.function.BinaryOperator
971 * @since 1.8
972 */
973 public static float max(float a, float b) {
974 return Math.max(a, b);
975 }
976
977 /**
978 * Returns the smaller of two {@code float} values
979 * as if by calling {@link Math#min(float, float) Math.min}.
980 *
981 * @param a the first operand
982 * @param b the second operand
983 * @return the smaller of {@code a} and {@code b}
984 * @see java.util.function.BinaryOperator
985 * @since 1.8
986 */
987 public static float min(float a, float b) {
988 return Math.min(a, b);
989 }
990
991 /**
992 * Returns an {@link Optional} containing the nominal descriptor for this
993 * instance, which is the instance itself.
994 *
995 * @return an {@link Optional} describing the {@linkplain Float} instance
996 * @since 12
997 */
998 @Override
999 public Optional<Float> describeConstable() {
1000 return Optional.of(this);
1001 }
1002
1003 /**
1004 * Resolves this instance as a {@link ConstantDesc}, the result of which is
1005 * the instance itself.
1006 *
1007 * @param lookup ignored
1008 * @return the {@linkplain Float} instance
1009 * @since 12
1010 */
1011 @Override
1012 public Float resolveConstantDesc(MethodHandles.Lookup lookup) {
1013 return this;
1014 }
1015
1016 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1017 @java.io.Serial
1018 private static final long serialVersionUID = -2671257302660747028L;
1019 }