1 /*
2 * Copyright (c) 1994, 2024, 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.FloatConsts;
34 import jdk.internal.math.FloatingDecimal;
35 import jdk.internal.math.FloatToDecimal;
36 import jdk.internal.vm.annotation.IntrinsicCandidate;
37
38 /**
39 * The {@code Float} class wraps a value of primitive type
40 * {@code float} in an object. An object of type
41 * {@code Float} contains a single field whose type is
42 * {@code float}.
43 *
44 * <p>In addition, this class provides several methods for converting a
45 * {@code float} to a {@code String} and a
46 * {@code String} to a {@code float}, as well as other
47 * constants and methods useful when dealing with a
48 * {@code float}.
49 *
50 * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
51 * class; programmers should treat instances that are
52 * {@linkplain #equals(Object) equal} as interchangeable and should not
53 * use instances for synchronization, or unpredictable behavior may
54 * occur. For example, in a future release, synchronization may fail.
55 *
56 * <h2><a id=equivalenceRelation>Floating-point Equality, Equivalence,
57 * and Comparison</a></h2>
58 *
59 * The class {@code java.lang.Double} has a {@linkplain
60 * Double##equivalenceRelation discussion of equality,
61 * equivalence, and comparison of floating-point values} that is
62 * equally applicable to {@code float} values.
63 *
64 * <h2><a id=decimalToBinaryConversion>Decimal ↔ Binary Conversion Issues</a></h2>
65 *
66 * The {@linkplain Double##decimalToBinaryConversion discussion of binary to
67 * decimal conversion issues} in {@code java.lang.Double} is also
68 * applicable to {@code float} values.
69 *
70 * @see <a href="https://standards.ieee.org/ieee/754/6210/">
71 * <cite>IEEE Standard for Floating-Point Arithmetic</cite></a>
72 *
73 * @author Lee Boynton
74 * @author Arthur van Hoff
75 * @author Joseph D. Darcy
76 * @since 1.0
77 */
78 @jdk.internal.MigratedValueClass
79 @jdk.internal.ValueBased
80 public final class Float extends Number
81 implements Comparable<Float>, Constable, ConstantDesc {
82 /**
83 * A constant holding the positive infinity of type
84 * {@code float}. It is equal to the value returned by
85 * {@code Float.intBitsToFloat(0x7f800000)}.
86 */
87 public static final float POSITIVE_INFINITY = 1.0f / 0.0f;
88
89 /**
90 * A constant holding the negative infinity of type
91 * {@code float}. It is equal to the value returned by
92 * {@code Float.intBitsToFloat(0xff800000)}.
93 */
94 public static final float NEGATIVE_INFINITY = -1.0f / 0.0f;
95
96 /**
97 * A constant holding a Not-a-Number (NaN) value of type
98 * {@code float}. It is equivalent to the value returned by
99 * {@code Float.intBitsToFloat(0x7fc00000)}.
100 */
101 public static final float NaN = 0.0f / 0.0f;
102
103 /**
104 * A constant holding the largest positive finite value of type
105 * {@code float}, (2-2<sup>-23</sup>)·2<sup>127</sup>.
106 * It is equal to the hexadecimal floating-point literal
107 * {@code 0x1.fffffeP+127f} and also equal to
108 * {@code Float.intBitsToFloat(0x7f7fffff)}.
109 */
110 public static final float MAX_VALUE = 0x1.fffffeP+127f; // 3.4028235e+38f
111
112 /**
113 * A constant holding the smallest positive normal value of type
114 * {@code float}, 2<sup>-126</sup>. It is equal to the
115 * hexadecimal floating-point literal {@code 0x1.0p-126f} and also
116 * equal to {@code Float.intBitsToFloat(0x00800000)}.
117 *
118 * @since 1.6
119 */
120 public static final float MIN_NORMAL = 0x1.0p-126f; // 1.17549435E-38f
121
122 /**
123 * A constant holding the smallest positive nonzero value of type
124 * {@code float}, 2<sup>-149</sup>. It is equal to the
125 * hexadecimal floating-point literal {@code 0x0.000002P-126f}
126 * and also equal to {@code Float.intBitsToFloat(0x1)}.
127 */
128 public static final float MIN_VALUE = 0x0.000002P-126f; // 1.4e-45f
129
130 /**
131 * The number of bits used to represent a {@code float} value.
132 *
133 * @since 1.5
134 */
135 public static final int SIZE = 32;
136
137 /**
138 * The number of bits in the significand of a {@code float} value.
139 * This is the parameter N in section {@jls 4.2.3} of
140 * <cite>The Java Language Specification</cite>.
141 *
142 * @since 19
143 */
144 public static final int PRECISION = 24;
145
146 /**
147 * Maximum exponent a finite {@code float} variable may have. It
148 * is equal to the value returned by {@code
149 * Math.getExponent(Float.MAX_VALUE)}.
150 *
151 * @since 1.6
152 */
153 public static final int MAX_EXPONENT = (1 << (SIZE - PRECISION - 1)) - 1; // 127
154
155 /**
156 * Minimum exponent a normalized {@code float} variable may have.
157 * It is equal to the value returned by {@code
158 * Math.getExponent(Float.MIN_NORMAL)}.
159 *
160 * @since 1.6
161 */
162 public static final int MIN_EXPONENT = 1 - MAX_EXPONENT; // -126
163
164 /**
165 * The number of bytes used to represent a {@code float} value.
166 *
167 * @since 1.8
168 */
169 public static final int BYTES = SIZE / Byte.SIZE;
170
171 /**
172 * The {@code Class} instance representing the primitive type
173 * {@code float}.
174 *
175 * @since 1.1
176 */
177 @SuppressWarnings("unchecked")
178 public static final Class<Float> TYPE = (Class<Float>) Class.getPrimitiveClass("float");
179
180 /**
181 * Returns a string representation of the {@code float}
182 * argument. All characters mentioned below are ASCII characters.
183 * <ul>
184 * <li>If the argument is NaN, the result is the string
185 * "{@code NaN}".
186 * <li>Otherwise, the result is a string that represents the sign and
187 * magnitude (absolute value) of the argument. If the sign is
188 * negative, the first character of the result is
189 * '{@code -}' ({@code '\u005Cu002D'}); if the sign is
190 * positive, no sign character appears in the result. As for
191 * the magnitude <i>m</i>:
192 * <ul>
193 * <li>If <i>m</i> is infinity, it is represented by the characters
194 * {@code "Infinity"}; thus, positive infinity produces
195 * the result {@code "Infinity"} and negative infinity
196 * produces the result {@code "-Infinity"}.
197 * <li>If <i>m</i> is zero, it is represented by the characters
198 * {@code "0.0"}; thus, negative zero produces the result
199 * {@code "-0.0"} and positive zero produces the result
200 * {@code "0.0"}.
201 *
202 * <li> Otherwise <i>m</i> is positive and finite.
203 * It is converted to a string in two stages:
204 * <ul>
205 * <li> <em>Selection of a decimal</em>:
206 * A well-defined decimal <i>d</i><sub><i>m</i></sub>
207 * is selected to represent <i>m</i>.
208 * This decimal is (almost always) the <em>shortest</em> one that
209 * rounds to <i>m</i> according to the round to nearest
210 * rounding policy of IEEE 754 floating-point arithmetic.
211 * <li> <em>Formatting as a string</em>:
212 * The decimal <i>d</i><sub><i>m</i></sub> is formatted as a string,
213 * either in plain or in computerized scientific notation,
214 * depending on its value.
215 * </ul>
216 * </ul>
217 * </ul>
218 *
219 * <p>A <em>decimal</em> is a number of the form
220 * <i>s</i>×10<sup><i>i</i></sup>
221 * for some (unique) integers <i>s</i> > 0 and <i>i</i> such that
222 * <i>s</i> is not a multiple of 10.
223 * These integers are the <em>significand</em> and
224 * the <em>exponent</em>, respectively, of the decimal.
225 * The <em>length</em> of the decimal is the (unique)
226 * positive integer <i>n</i> meeting
227 * 10<sup><i>n</i>-1</sup> ≤ <i>s</i> < 10<sup><i>n</i></sup>.
228 *
229 * <p>The decimal <i>d</i><sub><i>m</i></sub> for a finite positive <i>m</i>
230 * is defined as follows:
231 * <ul>
232 * <li>Let <i>R</i> be the set of all decimals that round to <i>m</i>
233 * according to the usual <em>round to nearest</em> rounding policy of
234 * IEEE 754 floating-point arithmetic.
235 * <li>Let <i>p</i> be the minimal length over all decimals in <i>R</i>.
236 * <li>When <i>p</i> ≥ 2, let <i>T</i> be the set of all decimals
237 * in <i>R</i> with length <i>p</i>.
238 * Otherwise, let <i>T</i> be the set of all decimals
239 * in <i>R</i> with length 1 or 2.
240 * <li>Define <i>d</i><sub><i>m</i></sub> as the decimal in <i>T</i>
241 * that is closest to <i>m</i>.
242 * Or if there are two such decimals in <i>T</i>,
243 * select the one with the even significand.
244 * </ul>
245 *
246 * <p>The (uniquely) selected decimal <i>d</i><sub><i>m</i></sub>
247 * is then formatted.
248 * Let <i>s</i>, <i>i</i> and <i>n</i> be the significand, exponent and
249 * length of <i>d</i><sub><i>m</i></sub>, respectively.
250 * Further, let <i>e</i> = <i>n</i> + <i>i</i> - 1 and let
251 * <i>s</i><sub>1</sub>…<i>s</i><sub><i>n</i></sub>
252 * be the usual decimal expansion of <i>s</i>.
253 * Note that <i>s</i><sub>1</sub> ≠ 0
254 * and <i>s</i><sub><i>n</i></sub> ≠ 0.
255 * Below, the decimal point {@code '.'} is {@code '\u005Cu002E'}
256 * and the exponent indicator {@code 'E'} is {@code '\u005Cu0045'}.
257 * <ul>
258 * <li>Case -3 ≤ <i>e</i> < 0:
259 * <i>d</i><sub><i>m</i></sub> is formatted as
260 * <code>0.0</code>…<code>0</code><!--
261 * --><i>s</i><sub>1</sub>…<i>s</i><sub><i>n</i></sub>,
262 * where there are exactly -(<i>n</i> + <i>i</i>) zeroes between
263 * the decimal point and <i>s</i><sub>1</sub>.
264 * For example, 123 × 10<sup>-4</sup> is formatted as
265 * {@code 0.0123}.
266 * <li>Case 0 ≤ <i>e</i> < 7:
267 * <ul>
268 * <li>Subcase <i>i</i> ≥ 0:
269 * <i>d</i><sub><i>m</i></sub> is formatted as
270 * <i>s</i><sub>1</sub>…<i>s</i><sub><i>n</i></sub><!--
271 * --><code>0</code>…<code>0.0</code>,
272 * where there are exactly <i>i</i> zeroes
273 * between <i>s</i><sub><i>n</i></sub> and the decimal point.
274 * For example, 123 × 10<sup>2</sup> is formatted as
275 * {@code 12300.0}.
276 * <li>Subcase <i>i</i> < 0:
277 * <i>d</i><sub><i>m</i></sub> is formatted as
278 * <i>s</i><sub>1</sub>…<!--
279 * --><i>s</i><sub><i>n</i>+<i>i</i></sub><code>.</code><!--
280 * --><i>s</i><sub><i>n</i>+<i>i</i>+1</sub>…<!--
281 * --><i>s</i><sub><i>n</i></sub>,
282 * where there are exactly -<i>i</i> digits to the right of
283 * the decimal point.
284 * For example, 123 × 10<sup>-1</sup> is formatted as
285 * {@code 12.3}.
286 * </ul>
287 * <li>Case <i>e</i> < -3 or <i>e</i> ≥ 7:
288 * computerized scientific notation is used to format
289 * <i>d</i><sub><i>m</i></sub>.
290 * Here <i>e</i> is formatted as by {@link Integer#toString(int)}.
291 * <ul>
292 * <li>Subcase <i>n</i> = 1:
293 * <i>d</i><sub><i>m</i></sub> is formatted as
294 * <i>s</i><sub>1</sub><code>.0E</code><i>e</i>.
295 * For example, 1 × 10<sup>23</sup> is formatted as
296 * {@code 1.0E23}.
297 * <li>Subcase <i>n</i> > 1:
298 * <i>d</i><sub><i>m</i></sub> is formatted as
299 * <i>s</i><sub>1</sub><code>.</code><i>s</i><sub>2</sub><!--
300 * -->…<i>s</i><sub><i>n</i></sub><code>E</code><i>e</i>.
301 * For example, 123 × 10<sup>-21</sup> is formatted as
302 * {@code 1.23E-19}.
303 * </ul>
304 * </ul>
305 *
306 * <p>To create localized string representations of a floating-point
307 * value, use subclasses of {@link java.text.NumberFormat}.
308 *
309 * @param f the {@code float} to be converted.
310 * @return a string representation of the argument.
311 */
312 public static String toString(float f) {
313 return FloatToDecimal.toString(f);
314 }
315
316 /**
317 * Returns a hexadecimal string representation of the
318 * {@code float} argument. All characters mentioned below are
319 * ASCII characters.
320 *
321 * <ul>
322 * <li>If the argument is NaN, the result is the string
323 * "{@code NaN}".
324 * <li>Otherwise, the result is a string that represents the sign and
325 * magnitude (absolute value) of the argument. If the sign is negative,
326 * the first character of the result is '{@code -}'
327 * ({@code '\u005Cu002D'}); if the sign is positive, no sign character
328 * appears in the result. As for the magnitude <i>m</i>:
329 *
330 * <ul>
331 * <li>If <i>m</i> is infinity, it is represented by the string
332 * {@code "Infinity"}; thus, positive infinity produces the
333 * result {@code "Infinity"} and negative infinity produces
334 * the result {@code "-Infinity"}.
335 *
336 * <li>If <i>m</i> is zero, it is represented by the string
337 * {@code "0x0.0p0"}; thus, negative zero produces the result
338 * {@code "-0x0.0p0"} and positive zero produces the result
339 * {@code "0x0.0p0"}.
340 *
341 * <li>If <i>m</i> is a {@code float} value with a
342 * normalized representation, substrings are used to represent the
343 * significand and exponent fields. The significand is
344 * represented by the characters {@code "0x1."}
345 * followed by a lowercase hexadecimal representation of the rest
346 * of the significand as a fraction. Trailing zeros in the
347 * hexadecimal representation are removed unless all the digits
348 * are zero, in which case a single zero is used. Next, the
349 * exponent is represented by {@code "p"} followed
350 * by a decimal string of the unbiased exponent as if produced by
351 * a call to {@link Integer#toString(int) Integer.toString} on the
352 * exponent value.
353 *
354 * <li>If <i>m</i> is a {@code float} value with a subnormal
355 * representation, the significand is represented by the
356 * characters {@code "0x0."} followed by a
357 * hexadecimal representation of the rest of the significand as a
358 * fraction. Trailing zeros in the hexadecimal representation are
359 * removed. Next, the exponent is represented by
360 * {@code "p-126"}. Note that there must be at
361 * least one nonzero digit in a subnormal significand.
362 *
363 * </ul>
364 *
365 * </ul>
366 *
367 * <table class="striped">
368 * <caption>Examples</caption>
369 * <thead>
370 * <tr><th scope="col">Floating-point Value</th><th scope="col">Hexadecimal String</th>
371 * </thead>
372 * <tbody>
373 * <tr><th scope="row">{@code 1.0}</th> <td>{@code 0x1.0p0}</td>
374 * <tr><th scope="row">{@code -1.0}</th> <td>{@code -0x1.0p0}</td>
375 * <tr><th scope="row">{@code 2.0}</th> <td>{@code 0x1.0p1}</td>
376 * <tr><th scope="row">{@code 3.0}</th> <td>{@code 0x1.8p1}</td>
377 * <tr><th scope="row">{@code 0.5}</th> <td>{@code 0x1.0p-1}</td>
378 * <tr><th scope="row">{@code 0.25}</th> <td>{@code 0x1.0p-2}</td>
379 * <tr><th scope="row">{@code Float.MAX_VALUE}</th>
380 * <td>{@code 0x1.fffffep127}</td>
381 * <tr><th scope="row">{@code Minimum Normal Value}</th>
382 * <td>{@code 0x1.0p-126}</td>
383 * <tr><th scope="row">{@code Maximum Subnormal Value}</th>
384 * <td>{@code 0x0.fffffep-126}</td>
385 * <tr><th scope="row">{@code Float.MIN_VALUE}</th>
386 * <td>{@code 0x0.000002p-126}</td>
387 * </tbody>
388 * </table>
389 * @param f the {@code float} to be converted.
390 * @return a hex string representation of the argument.
391 * @since 1.5
392 * @author Joseph D. Darcy
393 */
394 public static String toHexString(float f) {
395 if (Math.abs(f) < Float.MIN_NORMAL
396 && f != 0.0f ) {// float subnormal
397 // Adjust exponent to create subnormal double, then
398 // replace subnormal double exponent with subnormal float
399 // exponent
400 String s = Double.toHexString(Math.scalb((double)f,
401 /* -1022+126 */
402 Double.MIN_EXPONENT-
403 Float.MIN_EXPONENT));
404 return s.replaceFirst("p-1022$", "p-126");
405 }
406 else // double string will be the same as float string
407 return Double.toHexString(f);
408 }
409
410 /**
411 * Returns a {@code Float} object holding the
412 * {@code float} value represented by the argument string
413 * {@code s}.
414 *
415 * <p>If {@code s} is {@code null}, then a
416 * {@code NullPointerException} is thrown.
417 *
418 * <p>Leading and trailing whitespace characters in {@code s}
419 * are ignored. Whitespace is removed as if by the {@link
420 * String#trim} method; that is, both ASCII space and control
421 * characters are removed. The rest of {@code s} should
422 * constitute a <i>FloatValue</i> as described by the lexical
423 * syntax rules:
424 *
425 * <blockquote>
426 * <dl>
427 * <dt><i>FloatValue:</i>
428 * <dd><i>Sign<sub>opt</sub></i> {@code NaN}
429 * <dd><i>Sign<sub>opt</sub></i> {@code Infinity}
430 * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
431 * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
432 * <dd><i>SignedInteger</i>
433 * </dl>
434 *
435 * <dl>
436 * <dt><i>HexFloatingPointLiteral</i>:
437 * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
438 * </dl>
439 *
440 * <dl>
441 * <dt><i>HexSignificand:</i>
442 * <dd><i>HexNumeral</i>
443 * <dd><i>HexNumeral</i> {@code .}
444 * <dd>{@code 0x} <i>HexDigits<sub>opt</sub>
445 * </i>{@code .}<i> HexDigits</i>
446 * <dd>{@code 0X}<i> HexDigits<sub>opt</sub>
447 * </i>{@code .} <i>HexDigits</i>
448 * </dl>
449 *
450 * <dl>
451 * <dt><i>BinaryExponent:</i>
452 * <dd><i>BinaryExponentIndicator SignedInteger</i>
453 * </dl>
454 *
455 * <dl>
456 * <dt><i>BinaryExponentIndicator:</i>
457 * <dd>{@code p}
458 * <dd>{@code P}
459 * </dl>
460 *
461 * </blockquote>
462 *
463 * where <i>Sign</i>, <i>FloatingPointLiteral</i>,
464 * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
465 * <i>FloatTypeSuffix</i> are as defined in the lexical structure
466 * sections of
467 * <cite>The Java Language Specification</cite>,
468 * except that underscores are not accepted between digits.
469 * If {@code s} does not have the form of
470 * a <i>FloatValue</i>, then a {@code NumberFormatException}
471 * is thrown. Otherwise, {@code s} is regarded as
472 * representing an exact decimal value in the usual
473 * "computerized scientific notation" or as an exact
474 * hexadecimal value; this exact numerical value is then
475 * conceptually converted to an "infinitely precise"
476 * binary value that is then rounded to type {@code float}
477 * by the usual round-to-nearest rule of IEEE 754 floating-point
478 * arithmetic, which includes preserving the sign of a zero
479 * value.
480 *
481 * Note that the round-to-nearest rule also implies overflow and
482 * underflow behaviour; if the exact value of {@code s} is large
483 * enough in magnitude (greater than or equal to ({@link
484 * #MAX_VALUE} + {@link Math#ulp(float) ulp(MAX_VALUE)}/2),
485 * rounding to {@code float} will result in an infinity and if the
486 * exact value of {@code s} is small enough in magnitude (less
487 * than or equal to {@link #MIN_VALUE}/2), rounding to float will
488 * result in a zero.
489 *
490 * Finally, after rounding a {@code Float} object representing
491 * this {@code float} value is returned.
492 *
493 * <p>Note that trailing format specifiers, specifiers that
494 * determine the type of a floating-point literal
495 * ({@code 1.0f} is a {@code float} value;
496 * {@code 1.0d} is a {@code double} value), do
497 * <em>not</em> influence the results of this method. In other
498 * words, the numerical value of the input string is converted
499 * directly to the target floating-point type. In general, the
500 * two-step sequence of conversions, string to {@code double}
501 * followed by {@code double} to {@code float}, is
502 * <em>not</em> equivalent to converting a string directly to
503 * {@code float}. For example, if first converted to an
504 * intermediate {@code double} and then to
505 * {@code float}, the string<br>
506 * {@code "1.00000017881393421514957253748434595763683319091796875001d"}<br>
507 * results in the {@code float} value
508 * {@code 1.0000002f}; if the string is converted directly to
509 * {@code float}, <code>1.000000<b>1</b>f</code> results.
510 *
511 * <p>To avoid calling this method on an invalid string and having
512 * a {@code NumberFormatException} be thrown, the documentation
513 * for {@link Double#valueOf Double.valueOf} lists a regular
514 * expression which can be used to screen the input.
515 *
516 * @apiNote To interpret localized string representations of a
517 * floating-point value, or string representations that have
518 * non-ASCII digits, use {@link java.text.NumberFormat}. For
519 * example,
520 * {@snippet lang="java" :
521 * NumberFormat.getInstance(l).parse(s).floatValue();
522 * }
523 * where {@code l} is the desired locale, or
524 * {@link java.util.Locale#ROOT} if locale insensitive.
525 *
526 * @param s the string to be parsed.
527 * @return a {@code Float} object holding the value
528 * represented by the {@code String} argument.
529 * @throws NumberFormatException if the string does not contain a
530 * parsable number.
531 * @see Double##decimalToBinaryConversion Decimal ↔ Binary Conversion Issues
532 */
533 public static Float valueOf(String s) throws NumberFormatException {
534 return new Float(parseFloat(s));
535 }
536
537 /**
538 * Returns a {@code Float} instance representing the specified
539 * {@code float} value.
540 * If a new {@code Float} instance is not required, this method
541 * should generally be used in preference to the constructor
542 * {@link #Float(float)}, as this method is likely to yield
543 * significantly better space and time performance by caching
544 * frequently requested values.
545 *
546 * @param f a float value.
547 * @return a {@code Float} instance representing {@code f}.
548 * @since 1.5
549 */
550 @IntrinsicCandidate
551 public static Float valueOf(float f) {
552 return new Float(f);
553 }
554
555 /**
556 * Returns a new {@code float} initialized to the value
557 * represented by the specified {@code String}, as performed
558 * by the {@code valueOf} method of class {@code Float}.
559 *
560 * @param s the string to be parsed.
561 * @return the {@code float} value represented by the string
562 * argument.
563 * @throws NullPointerException if the string is null
564 * @throws NumberFormatException if the string does not contain a
565 * parsable {@code float}.
566 * @see java.lang.Float#valueOf(String)
567 * @see Double##decimalToBinaryConversion Decimal ↔ Binary Conversion Issues
568 * @since 1.2
569 */
570 public static float parseFloat(String s) throws NumberFormatException {
571 return FloatingDecimal.parseFloat(s);
572 }
573
574 /**
575 * Returns {@code true} if the specified number is a
576 * Not-a-Number (NaN) value, {@code false} otherwise.
577 *
578 * @apiNote
579 * This method corresponds to the isNaN operation defined in IEEE
580 * 754.
581 *
582 * @param v the value to be tested.
583 * @return {@code true} if the argument is NaN;
584 * {@code false} otherwise.
585 */
586 public static boolean isNaN(float v) {
587 return (v != v);
588 }
589
590 /**
591 * Returns {@code true} if the specified number is infinitely
592 * large in magnitude, {@code false} otherwise.
593 *
594 * @apiNote
595 * This method corresponds to the isInfinite operation defined in
596 * IEEE 754.
597 *
598 * @param v the value to be tested.
599 * @return {@code true} if the argument is positive infinity or
600 * negative infinity; {@code false} otherwise.
601 */
602 @IntrinsicCandidate
603 public static boolean isInfinite(float v) {
604 return Math.abs(v) > MAX_VALUE;
605 }
606
607
608 /**
609 * Returns {@code true} if the argument is a finite floating-point
610 * value; returns {@code false} otherwise (for NaN and infinity
611 * arguments).
612 *
613 * @apiNote
614 * This method corresponds to the isFinite operation defined in
615 * IEEE 754.
616 *
617 * @param f the {@code float} value to be tested
618 * @return {@code true} if the argument is a finite
619 * floating-point value, {@code false} otherwise.
620 * @since 1.8
621 */
622 @IntrinsicCandidate
623 public static boolean isFinite(float f) {
624 return Math.abs(f) <= Float.MAX_VALUE;
625 }
626
627 /**
628 * The value of the Float.
629 *
630 * @serial
631 */
632 private final float value;
633
634 /**
635 * Constructs a newly allocated {@code Float} object that
636 * represents the primitive {@code float} argument.
637 *
638 * @param value the value to be represented by the {@code Float}.
639 *
640 * @deprecated
641 * It is rarely appropriate to use this constructor. The static factory
642 * {@link #valueOf(float)} is generally a better choice, as it is
643 * likely to yield significantly better space and time performance.
644 */
645 @Deprecated(since="9", forRemoval = true)
646 public Float(float value) {
647 this.value = value;
648 }
649
650 /**
651 * Constructs a newly allocated {@code Float} object that
652 * represents the argument converted to type {@code float}.
653 *
654 * @param value the value to be represented by the {@code Float}.
655 *
656 * @deprecated
657 * It is rarely appropriate to use this constructor. Instead, use the
658 * static factory method {@link #valueOf(float)} method as follows:
659 * {@code Float.valueOf((float)value)}.
660 */
661 @Deprecated(since="9", forRemoval = true)
662 public Float(double value) {
663 this.value = (float)value;
664 }
665
666 /**
667 * Constructs a newly allocated {@code Float} object that
668 * represents the floating-point value of type {@code float}
669 * represented by the string. The string is converted to a
670 * {@code float} value as if by the {@code valueOf} method.
671 *
672 * @param s a string to be converted to a {@code Float}.
673 * @throws NumberFormatException if the string does not contain a
674 * parsable number.
675 *
676 * @deprecated
677 * It is rarely appropriate to use this constructor.
678 * Use {@link #parseFloat(String)} to convert a string to a
679 * {@code float} primitive, or use {@link #valueOf(String)}
680 * to convert a string to a {@code Float} object.
681 */
682 @Deprecated(since="9", forRemoval = true)
683 public Float(String s) throws NumberFormatException {
684 value = parseFloat(s);
685 }
686
687 /**
688 * Returns {@code true} if this {@code Float} value is a
689 * Not-a-Number (NaN), {@code false} otherwise.
690 *
691 * @return {@code true} if the value represented by this object is
692 * NaN; {@code false} otherwise.
693 */
694 public boolean isNaN() {
695 return isNaN(value);
696 }
697
698 /**
699 * Returns {@code true} if this {@code Float} value is
700 * infinitely large in magnitude, {@code false} otherwise.
701 *
702 * @return {@code true} if the value represented by this object is
703 * positive infinity or negative infinity;
704 * {@code false} otherwise.
705 */
706 public boolean isInfinite() {
707 return isInfinite(value);
708 }
709
710 /**
711 * Returns a string representation of this {@code Float} object.
712 * The primitive {@code float} value represented by this object
713 * is converted to a {@code String} exactly as if by the method
714 * {@code toString} of one argument.
715 *
716 * @return a {@code String} representation of this object.
717 * @see java.lang.Float#toString(float)
718 */
719 public String toString() {
720 return Float.toString(value);
721 }
722
723 /**
724 * Returns the value of this {@code Float} as a {@code byte} after
725 * a narrowing primitive conversion.
726 *
727 * @return the {@code float} value represented by this object
728 * converted to type {@code byte}
729 * @jls 5.1.3 Narrowing Primitive Conversion
730 */
731 public byte byteValue() {
732 return (byte)value;
733 }
734
735 /**
736 * Returns the value of this {@code Float} as a {@code short}
737 * after a narrowing primitive conversion.
738 *
739 * @return the {@code float} value represented by this object
740 * converted to type {@code short}
741 * @jls 5.1.3 Narrowing Primitive Conversion
742 * @since 1.1
743 */
744 public short shortValue() {
745 return (short)value;
746 }
747
748 /**
749 * Returns the value of this {@code Float} as an {@code int} after
750 * a narrowing primitive conversion.
751 *
752 * @return the {@code float} value represented by this object
753 * converted to type {@code int}
754 * @jls 5.1.3 Narrowing Primitive Conversion
755 */
756 public int intValue() {
757 return (int)value;
758 }
759
760 /**
761 * Returns value of this {@code Float} as a {@code long} after a
762 * narrowing primitive conversion.
763 *
764 * @return the {@code float} value represented by this object
765 * converted to type {@code long}
766 * @jls 5.1.3 Narrowing Primitive Conversion
767 */
768 public long longValue() {
769 return (long)value;
770 }
771
772 /**
773 * Returns the {@code float} value of this {@code Float} object.
774 *
775 * @return the {@code float} value represented by this object
776 */
777 @IntrinsicCandidate
778 public float floatValue() {
779 return value;
780 }
781
782 /**
783 * Returns the value of this {@code Float} as a {@code double}
784 * after a widening primitive conversion.
785 *
786 * @apiNote
787 * This method corresponds to the convertFormat operation defined
788 * in IEEE 754.
789 *
790 * @return the {@code float} value represented by this
791 * object converted to type {@code double}
792 * @jls 5.1.2 Widening Primitive Conversion
793 */
794 public double doubleValue() {
795 return (double)value;
796 }
797
798 /**
799 * Returns a hash code for this {@code Float} object. The
800 * result is the integer bit representation, exactly as produced
801 * by the method {@link #floatToIntBits(float)}, of the primitive
802 * {@code float} value represented by this {@code Float}
803 * object.
804 *
805 * @return a hash code value for this object.
806 */
807 @Override
808 public int hashCode() {
809 return Float.hashCode(value);
810 }
811
812 /**
813 * Returns a hash code for a {@code float} value; compatible with
814 * {@code Float.hashCode()}.
815 *
816 * @param value the value to hash
817 * @return a hash code value for a {@code float} value.
818 * @since 1.8
819 */
820 public static int hashCode(float value) {
821 return floatToIntBits(value);
822 }
823
824 /**
825 * Compares this object against the specified object. The result
826 * is {@code true} if and only if the argument is not
827 * {@code null} and is a {@code Float} object that
828 * represents a {@code float} with the same value as the
829 * {@code float} represented by this object. For this
830 * purpose, two {@code float} values are considered to be the
831 * same if and only if the method {@link #floatToIntBits(float)}
832 * returns the identical {@code int} value when applied to
833 * each.
834 *
835 * @apiNote
836 * This method is defined in terms of {@link
837 * #floatToIntBits(float)} rather than the {@code ==} operator on
838 * {@code float} values since the {@code ==} operator does
839 * <em>not</em> define an equivalence relation and to satisfy the
840 * {@linkplain Object#equals equals contract} an equivalence
841 * relation must be implemented; see <a
842 * href="Double.html#equivalenceRelation">this discussion</a> for
843 * details of floating-point equality and equivalence.
844 *
845 * @param obj the object to be compared
846 * @return {@code true} if the objects are the same;
847 * {@code false} otherwise.
848 * @see java.lang.Float#floatToIntBits(float)
849 * @jls 15.21.1 Numerical Equality Operators == and !=
850 */
851 public boolean equals(Object obj) {
852 return (obj instanceof Float)
853 && (floatToIntBits(((Float)obj).value) == floatToIntBits(value));
854 }
855
856 /**
857 * Returns a representation of the specified floating-point value
858 * according to the IEEE 754 floating-point "single format" bit
859 * layout.
860 *
861 * <p>Bit 31 (the bit that is selected by the mask
862 * {@code 0x80000000}) represents the sign of the floating-point
863 * number.
864 * Bits 30-23 (the bits that are selected by the mask
865 * {@code 0x7f800000}) represent the exponent.
866 * Bits 22-0 (the bits that are selected by the mask
867 * {@code 0x007fffff}) represent the significand (sometimes called
868 * the mantissa) of the floating-point number.
869 *
870 * <p>If the argument is positive infinity, the result is
871 * {@code 0x7f800000}.
872 *
873 * <p>If the argument is negative infinity, the result is
874 * {@code 0xff800000}.
875 *
876 * <p>If the argument is NaN, the result is {@code 0x7fc00000}.
877 *
878 * <p>In all cases, the result is an integer that, when given to the
879 * {@link #intBitsToFloat(int)} method, will produce a floating-point
880 * value the same as the argument to {@code floatToIntBits}
881 * (except all NaN values are collapsed to a single
882 * "canonical" NaN value).
883 *
884 * @param value a floating-point number.
885 * @return the bits that represent the floating-point number.
886 */
887 @IntrinsicCandidate
888 public static int floatToIntBits(float value) {
889 if (!isNaN(value)) {
890 return floatToRawIntBits(value);
891 }
892 return 0x7fc00000;
893 }
894
895 /**
896 * Returns a representation of the specified floating-point value
897 * according to the IEEE 754 floating-point "single format" bit
898 * layout, preserving Not-a-Number (NaN) values.
899 *
900 * <p>Bit 31 (the bit that is selected by the mask
901 * {@code 0x80000000}) represents the sign of the floating-point
902 * number.
903 * Bits 30-23 (the bits that are selected by the mask
904 * {@code 0x7f800000}) represent the exponent.
905 * Bits 22-0 (the bits that are selected by the mask
906 * {@code 0x007fffff}) represent the significand (sometimes called
907 * the mantissa) of the floating-point number.
908 *
909 * <p>If the argument is positive infinity, the result is
910 * {@code 0x7f800000}.
911 *
912 * <p>If the argument is negative infinity, the result is
913 * {@code 0xff800000}.
914 *
915 * <p>If the argument is NaN, the result is the integer representing
916 * the actual NaN value. Unlike the {@code floatToIntBits}
917 * method, {@code floatToRawIntBits} does not collapse all the
918 * bit patterns encoding a NaN to a single "canonical"
919 * NaN value.
920 *
921 * <p>In all cases, the result is an integer that, when given to the
922 * {@link #intBitsToFloat(int)} method, will produce a
923 * floating-point value the same as the argument to
924 * {@code floatToRawIntBits}.
925 *
926 * @param value a floating-point number.
927 * @return the bits that represent the floating-point number.
928 * @since 1.3
929 */
930 @IntrinsicCandidate
931 public static native int floatToRawIntBits(float value);
932
933 /**
934 * Returns the {@code float} value corresponding to a given
935 * bit representation.
936 * The argument is considered to be a representation of a
937 * floating-point value according to the IEEE 754 floating-point
938 * "single format" bit layout.
939 *
940 * <p>If the argument is {@code 0x7f800000}, the result is positive
941 * infinity.
942 *
943 * <p>If the argument is {@code 0xff800000}, the result is negative
944 * infinity.
945 *
946 * <p>If the argument is any value in the range
947 * {@code 0x7f800001} through {@code 0x7fffffff} or in
948 * the range {@code 0xff800001} through
949 * {@code 0xffffffff}, the result is a NaN. No IEEE 754
950 * floating-point operation provided by Java can distinguish
951 * between two NaN values of the same type with different bit
952 * patterns. Distinct values of NaN are only distinguishable by
953 * use of the {@code Float.floatToRawIntBits} method.
954 *
955 * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
956 * values that can be computed from the argument:
957 *
958 * {@snippet lang="java" :
959 * int s = ((bits >> 31) == 0) ? 1 : -1;
960 * int e = ((bits >> 23) & 0xff);
961 * int m = (e == 0) ?
962 * (bits & 0x7fffff) << 1 :
963 * (bits & 0x7fffff) | 0x800000;
964 * }
965 *
966 * Then the floating-point result equals the value of the mathematical
967 * expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-150</sup>.
968 *
969 * <p>Note that this method may not be able to return a
970 * {@code float} NaN with exactly same bit pattern as the
971 * {@code int} argument. IEEE 754 distinguishes between two
972 * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The
973 * differences between the two kinds of NaN are generally not
974 * visible in Java. Arithmetic operations on signaling NaNs turn
975 * them into quiet NaNs with a different, but often similar, bit
976 * pattern. However, on some processors merely copying a
977 * signaling NaN also performs that conversion. In particular,
978 * copying a signaling NaN to return it to the calling method may
979 * perform this conversion. So {@code intBitsToFloat} may
980 * not be able to return a {@code float} with a signaling NaN
981 * bit pattern. Consequently, for some {@code int} values,
982 * {@code floatToRawIntBits(intBitsToFloat(start))} may
983 * <i>not</i> equal {@code start}. Moreover, which
984 * particular bit patterns represent signaling NaNs is platform
985 * dependent; although all NaN bit patterns, quiet or signaling,
986 * must be in the NaN range identified above.
987 *
988 * @param bits an integer.
989 * @return the {@code float} floating-point value with the same bit
990 * pattern.
991 */
992 @IntrinsicCandidate
993 public static native float intBitsToFloat(int bits);
994
995 /**
996 * {@return the {@code float} value closest to the numerical value
997 * of the argument, a floating-point binary16 value encoded in a
998 * {@code short}} The conversion is exact; all binary16 values can
999 * be exactly represented in {@code float}.
1000 *
1001 * Special cases:
1002 * <ul>
1003 * <li> If the argument is zero, the result is a zero with the
1004 * same sign as the argument.
1005 * <li> If the argument is infinite, the result is an infinity
1006 * with the same sign as the argument.
1007 * <li> If the argument is a NaN, the result is a NaN.
1008 * </ul>
1009 *
1010 * <h4><a id=binary16Format>IEEE 754 binary16 format</a></h4>
1011 * The IEEE 754 standard defines binary16 as a 16-bit format, along
1012 * with the 32-bit binary32 format (corresponding to the {@code
1013 * float} type) and the 64-bit binary64 format (corresponding to
1014 * the {@code double} type). The binary16 format is similar to the
1015 * other IEEE 754 formats, except smaller, having all the usual
1016 * IEEE 754 values such as NaN, signed infinities, signed zeros,
1017 * and subnormals. The parameters (JLS {@jls 4.2.3}) for the
1018 * binary16 format are N = 11 precision bits, K = 5 exponent bits,
1019 * <i>E</i><sub><i>max</i></sub> = 15, and
1020 * <i>E</i><sub><i>min</i></sub> = -14.
1021 *
1022 * @apiNote
1023 * This method corresponds to the convertFormat operation defined
1024 * in IEEE 754 from the binary16 format to the binary32 format.
1025 * The operation of this method is analogous to a primitive
1026 * widening conversion (JLS {@jls 5.1.2}).
1027 *
1028 * @param floatBinary16 the binary16 value to convert to {@code float}
1029 * @since 20
1030 */
1031 @IntrinsicCandidate
1032 public static float float16ToFloat(short floatBinary16) {
1033 /*
1034 * The binary16 format has 1 sign bit, 5 exponent bits, and 10
1035 * significand bits. The exponent bias is 15.
1036 */
1037 int bin16arg = (int)floatBinary16;
1038 int bin16SignBit = 0x8000 & bin16arg;
1039 int bin16ExpBits = 0x7c00 & bin16arg;
1040 int bin16SignifBits = 0x03FF & bin16arg;
1041
1042 // Shift left difference in the number of significand bits in
1043 // the float and binary16 formats
1044 final int SIGNIF_SHIFT = (FloatConsts.SIGNIFICAND_WIDTH - 11);
1045
1046 float sign = (bin16SignBit != 0) ? -1.0f : 1.0f;
1047
1048 // Extract binary16 exponent, remove its bias, add in the bias
1049 // of a float exponent and shift to correct bit location
1050 // (significand width includes the implicit bit so shift one
1051 // less).
1052 int bin16Exp = (bin16ExpBits >> 10) - 15;
1053 if (bin16Exp == -15) {
1054 // For subnormal binary16 values and 0, the numerical
1055 // value is 2^24 * the significand as an integer (no
1056 // implicit bit).
1057 return sign * (0x1p-24f * bin16SignifBits);
1058 } else if (bin16Exp == 16) {
1059 return (bin16SignifBits == 0) ?
1060 sign * Float.POSITIVE_INFINITY :
1061 Float.intBitsToFloat((bin16SignBit << 16) |
1062 0x7f80_0000 |
1063 // Preserve NaN signif bits
1064 ( bin16SignifBits << SIGNIF_SHIFT ));
1065 }
1066
1067 assert -15 < bin16Exp && bin16Exp < 16;
1068
1069 int floatExpBits = (bin16Exp + FloatConsts.EXP_BIAS)
1070 << (FloatConsts.SIGNIFICAND_WIDTH - 1);
1071
1072 // Compute and combine result sign, exponent, and significand bits.
1073 return Float.intBitsToFloat((bin16SignBit << 16) |
1074 floatExpBits |
1075 (bin16SignifBits << SIGNIF_SHIFT));
1076 }
1077
1078 /**
1079 * {@return the floating-point binary16 value, encoded in a {@code
1080 * short}, closest in value to the argument}
1081 * The conversion is computed under the {@linkplain
1082 * java.math.RoundingMode#HALF_EVEN round to nearest even rounding
1083 * mode}.
1084 *
1085 * Special cases:
1086 * <ul>
1087 * <li> If the argument is zero, the result is a zero with the
1088 * same sign as the argument.
1089 * <li> If the argument is infinite, the result is an infinity
1090 * with the same sign as the argument.
1091 * <li> If the argument is a NaN, the result is a NaN.
1092 * </ul>
1093 *
1094 * The <a href="#binary16Format">binary16 format</a> is discussed in
1095 * more detail in the {@link #float16ToFloat} method.
1096 *
1097 * @apiNote
1098 * This method corresponds to the convertFormat operation defined
1099 * in IEEE 754 from the binary32 format to the binary16 format.
1100 * The operation of this method is analogous to a primitive
1101 * narrowing conversion (JLS {@jls 5.1.3}).
1102 *
1103 * @param f the {@code float} value to convert to binary16
1104 * @since 20
1105 */
1106 @IntrinsicCandidate
1107 public static short floatToFloat16(float f) {
1108 int doppel = Float.floatToRawIntBits(f);
1109 short sign_bit = (short)((doppel & 0x8000_0000) >> 16);
1110
1111 if (Float.isNaN(f)) {
1112 // Preserve sign and attempt to preserve significand bits
1113 return (short)(sign_bit
1114 | 0x7c00 // max exponent + 1
1115 // Preserve high order bit of float NaN in the
1116 // binary16 result NaN (tenth bit); OR in remaining
1117 // bits into lower 9 bits of binary 16 significand.
1118 | (doppel & 0x007f_e000) >> 13 // 10 bits
1119 | (doppel & 0x0000_1ff0) >> 4 // 9 bits
1120 | (doppel & 0x0000_000f)); // 4 bits
1121 }
1122
1123 float abs_f = Math.abs(f);
1124
1125 // The overflow threshold is binary16 MAX_VALUE + 1/2 ulp
1126 if (abs_f >= (0x1.ffcp15f + 0x0.002p15f) ) {
1127 return (short)(sign_bit | 0x7c00); // Positive or negative infinity
1128 }
1129
1130 // Smallest magnitude nonzero representable binary16 value
1131 // is equal to 0x1.0p-24; half-way and smaller rounds to zero.
1132 if (abs_f <= 0x1.0p-24f * 0.5f) { // Covers float zeros and subnormals.
1133 return sign_bit; // Positive or negative zero
1134 }
1135
1136 // Dealing with finite values in exponent range of binary16
1137 // (when rounding is done, could still round up)
1138 int exp = Math.getExponent(f);
1139 assert -25 <= exp && exp <= 15;
1140
1141 // For binary16 subnormals, beside forcing exp to -15, retain
1142 // the difference expdelta = E_min - exp. This is the excess
1143 // shift value, in addition to 13, to be used in the
1144 // computations below. Further the (hidden) msb with value 1
1145 // in f must be involved as well.
1146 int expdelta = 0;
1147 int msb = 0x0000_0000;
1148 if (exp < -14) {
1149 expdelta = -14 - exp;
1150 exp = -15;
1151 msb = 0x0080_0000;
1152 }
1153 int f_signif_bits = doppel & 0x007f_ffff | msb;
1154
1155 // Significand bits as if using rounding to zero (truncation).
1156 short signif_bits = (short)(f_signif_bits >> (13 + expdelta));
1157
1158 // For round to nearest even, determining whether or not to
1159 // round up (in magnitude) is a function of the least
1160 // significant bit (LSB), the next bit position (the round
1161 // position), and the sticky bit (whether there are any
1162 // nonzero bits in the exact result to the right of the round
1163 // digit). An increment occurs in three cases:
1164 //
1165 // LSB Round Sticky
1166 // 0 1 1
1167 // 1 1 0
1168 // 1 1 1
1169 // See "Computer Arithmetic Algorithms," Koren, Table 4.9
1170
1171 int lsb = f_signif_bits & (1 << 13 + expdelta);
1172 int round = f_signif_bits & (1 << 12 + expdelta);
1173 int sticky = f_signif_bits & ((1 << 12 + expdelta) - 1);
1174
1175 if (round != 0 && ((lsb | sticky) != 0 )) {
1176 signif_bits++;
1177 }
1178
1179 // No bits set in significand beyond the *first* exponent bit,
1180 // not just the significand; quantity is added to the exponent
1181 // to implement a carry out from rounding the significand.
1182 assert (0xf800 & signif_bits) == 0x0;
1183
1184 return (short)(sign_bit | ( ((exp + 15) << 10) + signif_bits ) );
1185 }
1186
1187 /**
1188 * Compares two {@code Float} objects numerically.
1189 *
1190 * This method imposes a total order on {@code Float} objects
1191 * with two differences compared to the incomplete order defined by
1192 * the Java language numerical comparison operators ({@code <, <=,
1193 * ==, >=, >}) on {@code float} values.
1194 *
1195 * <ul><li> A NaN is <em>unordered</em> with respect to other
1196 * values and unequal to itself under the comparison
1197 * operators. This method chooses to define {@code
1198 * Float.NaN} to be equal to itself and greater than all
1199 * other {@code double} values (including {@code
1200 * Float.POSITIVE_INFINITY}).
1201 *
1202 * <li> Positive zero and negative zero compare equal
1203 * numerically, but are distinct and distinguishable values.
1204 * This method chooses to define positive zero ({@code +0.0f}),
1205 * to be greater than negative zero ({@code -0.0f}).
1206 * </ul>
1207 *
1208 * This ensures that the <i>natural ordering</i> of {@code Float}
1209 * objects imposed by this method is <i>consistent with
1210 * equals</i>; see <a href="Double.html#equivalenceRelation">this
1211 * discussion</a> for details of floating-point comparison and
1212 * ordering.
1213 *
1214 *
1215 * @param anotherFloat the {@code Float} to be compared.
1216 * @return the value {@code 0} if {@code anotherFloat} is
1217 * numerically equal to this {@code Float}; a value
1218 * less than {@code 0} if this {@code Float}
1219 * is numerically less than {@code anotherFloat};
1220 * and a value greater than {@code 0} if this
1221 * {@code Float} is numerically greater than
1222 * {@code anotherFloat}.
1223 *
1224 * @jls 15.20.1 Numerical Comparison Operators {@code <}, {@code <=}, {@code >}, and {@code >=}
1225 * @since 1.2
1226 */
1227 public int compareTo(Float anotherFloat) {
1228 return Float.compare(value, anotherFloat.value);
1229 }
1230
1231 /**
1232 * Compares the two specified {@code float} values. The sign
1233 * of the integer value returned is the same as that of the
1234 * integer that would be returned by the call:
1235 * <pre>
1236 * Float.valueOf(f1).compareTo(Float.valueOf(f2))
1237 * </pre>
1238 *
1239 * @param f1 the first {@code float} to compare.
1240 * @param f2 the second {@code float} to compare.
1241 * @return the value {@code 0} if {@code f1} is
1242 * numerically equal to {@code f2}; a value less than
1243 * {@code 0} if {@code f1} is numerically less than
1244 * {@code f2}; and a value greater than {@code 0}
1245 * if {@code f1} is numerically greater than
1246 * {@code f2}.
1247 * @since 1.4
1248 */
1249 public static int compare(float f1, float f2) {
1250 if (f1 < f2)
1251 return -1; // Neither val is NaN, thisVal is smaller
1252 if (f1 > f2)
1253 return 1; // Neither val is NaN, thisVal is larger
1254
1255 // Cannot use floatToRawIntBits because of possibility of NaNs.
1256 int thisBits = Float.floatToIntBits(f1);
1257 int anotherBits = Float.floatToIntBits(f2);
1258
1259 return (thisBits == anotherBits ? 0 : // Values are equal
1260 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
1261 1)); // (0.0, -0.0) or (NaN, !NaN)
1262 }
1263
1264 /**
1265 * Adds two {@code float} values together as per the + operator.
1266 *
1267 * @apiNote This method corresponds to the addition operation
1268 * defined in IEEE 754.
1269 *
1270 * @param a the first operand
1271 * @param b the second operand
1272 * @return the sum of {@code a} and {@code b}
1273 * @jls 4.2.4 Floating-Point Operations
1274 * @see java.util.function.BinaryOperator
1275 * @since 1.8
1276 */
1277 public static float sum(float a, float b) {
1278 return a + b;
1279 }
1280
1281 /**
1282 * Returns the greater of two {@code float} values
1283 * as if by calling {@link Math#max(float, float) Math.max}.
1284 *
1285 * @apiNote
1286 * This method corresponds to the maximum operation defined in
1287 * IEEE 754.
1288 *
1289 * @param a the first operand
1290 * @param b the second operand
1291 * @return the greater of {@code a} and {@code b}
1292 * @see java.util.function.BinaryOperator
1293 * @since 1.8
1294 */
1295 public static float max(float a, float b) {
1296 return Math.max(a, b);
1297 }
1298
1299 /**
1300 * Returns the smaller of two {@code float} values
1301 * as if by calling {@link Math#min(float, float) Math.min}.
1302 *
1303 * @apiNote
1304 * This method corresponds to the minimum operation defined in
1305 * IEEE 754.
1306 *
1307 * @param a the first operand
1308 * @param b the second operand
1309 * @return the smaller of {@code a} and {@code b}
1310 * @see java.util.function.BinaryOperator
1311 * @since 1.8
1312 */
1313 public static float min(float a, float b) {
1314 return Math.min(a, b);
1315 }
1316
1317 /**
1318 * Returns an {@link Optional} containing the nominal descriptor for this
1319 * instance, which is the instance itself.
1320 *
1321 * @return an {@link Optional} describing the {@linkplain Float} instance
1322 * @since 12
1323 */
1324 @Override
1325 public Optional<Float> describeConstable() {
1326 return Optional.of(this);
1327 }
1328
1329 /**
1330 * Resolves this instance as a {@link ConstantDesc}, the result of which is
1331 * the instance itself.
1332 *
1333 * @param lookup ignored
1334 * @return the {@linkplain Float} instance
1335 * @since 12
1336 */
1337 @Override
1338 public Float resolveConstantDesc(MethodHandles.Lookup lookup) {
1339 return this;
1340 }
1341
1342 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1343 @java.io.Serial
1344 private static final long serialVersionUID = -2671257302660747028L;
1345 }