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.ValueBased
79 public final class Float extends Number
80 implements Comparable<Float>, Constable, ConstantDesc {
81 /**
82 * A constant holding the positive infinity of type
83 * {@code float}. It is equal to the value returned by
84 * {@code Float.intBitsToFloat(0x7f800000)}.
85 */
86 public static final float POSITIVE_INFINITY = 1.0f / 0.0f;
87
88 /**
89 * A constant holding the negative infinity of type
90 * {@code float}. It is equal to the value returned by
91 * {@code Float.intBitsToFloat(0xff800000)}.
92 */
93 public static final float NEGATIVE_INFINITY = -1.0f / 0.0f;
94
95 /**
96 * A constant holding a Not-a-Number (NaN) value of type
97 * {@code float}. It is equivalent to the value returned by
98 * {@code Float.intBitsToFloat(0x7fc00000)}.
99 */
100 public static final float NaN = 0.0f / 0.0f;
101
102 /**
103 * A constant holding the largest positive finite value of type
104 * {@code float}, (2-2<sup>-23</sup>)·2<sup>127</sup>.
105 * It is equal to the hexadecimal floating-point literal
106 * {@code 0x1.fffffeP+127f} and also equal to
107 * {@code Float.intBitsToFloat(0x7f7fffff)}.
108 */
109 public static final float MAX_VALUE = 0x1.fffffeP+127f; // 3.4028235e+38f
110
111 /**
112 * A constant holding the smallest positive normal value of type
113 * {@code float}, 2<sup>-126</sup>. It is equal to the
114 * hexadecimal floating-point literal {@code 0x1.0p-126f} and also
115 * equal to {@code Float.intBitsToFloat(0x00800000)}.
116 *
117 * @since 1.6
118 */
119 public static final float MIN_NORMAL = 0x1.0p-126f; // 1.17549435E-38f
120
121 /**
122 * A constant holding the smallest positive nonzero value of type
123 * {@code float}, 2<sup>-149</sup>. It is equal to the
124 * hexadecimal floating-point literal {@code 0x0.000002P-126f}
125 * and also equal to {@code Float.intBitsToFloat(0x1)}.
126 */
127 public static final float MIN_VALUE = 0x0.000002P-126f; // 1.4e-45f
128
129 /**
130 * The number of bits used to represent a {@code float} value,
131 * {@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 * {@value}. 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,
148 * {@value}. It 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 * {@value}. 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 * {@value}.
167 *
168 * @since 1.8
169 */
170 public static final int BYTES = SIZE / Byte.SIZE;
171
172 /**
173 * The {@code Class} instance representing the primitive type
174 * {@code float}.
175 *
176 * @since 1.1
177 */
178 @SuppressWarnings("unchecked")
179 public static final Class<Float> TYPE = (Class<Float>) Class.getPrimitiveClass("float");
180
181 /**
182 * Returns a string representation of the {@code float}
183 * argument. All characters mentioned below are ASCII characters.
184 * <ul>
185 * <li>If the argument is NaN, the result is the string
186 * "{@code NaN}".
187 * <li>Otherwise, the result is a string that represents the sign and
188 * magnitude (absolute value) of the argument. If the sign is
189 * negative, the first character of the result is
190 * '{@code -}' ({@code '\u005Cu002D'}); if the sign is
191 * positive, no sign character appears in the result. As for
192 * the magnitude <i>m</i>:
193 * <ul>
194 * <li>If <i>m</i> is infinity, it is represented by the characters
195 * {@code "Infinity"}; thus, positive infinity produces
196 * the result {@code "Infinity"} and negative infinity
197 * produces the result {@code "-Infinity"}.
198 * <li>If <i>m</i> is zero, it is represented by the characters
199 * {@code "0.0"}; thus, negative zero produces the result
200 * {@code "-0.0"} and positive zero produces the result
201 * {@code "0.0"}.
202 *
203 * <li> Otherwise <i>m</i> is positive and finite.
204 * It is converted to a string in two stages:
205 * <ul>
206 * <li> <em>Selection of a decimal</em>:
207 * A well-defined decimal <i>d</i><sub><i>m</i></sub>
208 * is selected to represent <i>m</i>.
209 * This decimal is (almost always) the <em>shortest</em> one that
210 * rounds to <i>m</i> according to the round to nearest
211 * rounding policy of IEEE 754 floating-point arithmetic.
212 * <li> <em>Formatting as a string</em>:
213 * The decimal <i>d</i><sub><i>m</i></sub> is formatted as a string,
214 * either in plain or in computerized scientific notation,
215 * depending on its value.
216 * </ul>
217 * </ul>
218 * </ul>
219 *
220 * <p>A <em>decimal</em> is a number of the form
221 * <i>s</i>×10<sup><i>i</i></sup>
222 * for some (unique) integers <i>s</i> > 0 and <i>i</i> such that
223 * <i>s</i> is not a multiple of 10.
224 * These integers are the <em>significand</em> and
225 * the <em>exponent</em>, respectively, of the decimal.
226 * The <em>length</em> of the decimal is the (unique)
227 * positive integer <i>n</i> meeting
228 * 10<sup><i>n</i>-1</sup> ≤ <i>s</i> < 10<sup><i>n</i></sup>.
229 *
230 * <p>The decimal <i>d</i><sub><i>m</i></sub> for a finite positive <i>m</i>
231 * is defined as follows:
232 * <ul>
233 * <li>Let <i>R</i> be the set of all decimals that round to <i>m</i>
234 * according to the usual <em>round to nearest</em> rounding policy of
235 * IEEE 754 floating-point arithmetic.
236 * <li>Let <i>p</i> be the minimal length over all decimals in <i>R</i>.
237 * <li>When <i>p</i> ≥ 2, let <i>T</i> be the set of all decimals
238 * in <i>R</i> with length <i>p</i>.
239 * Otherwise, let <i>T</i> be the set of all decimals
240 * in <i>R</i> with length 1 or 2.
241 * <li>Define <i>d</i><sub><i>m</i></sub> as the decimal in <i>T</i>
242 * that is closest to <i>m</i>.
243 * Or if there are two such decimals in <i>T</i>,
244 * select the one with the even significand.
245 * </ul>
246 *
247 * <p>The (uniquely) selected decimal <i>d</i><sub><i>m</i></sub>
248 * is then formatted.
249 * Let <i>s</i>, <i>i</i> and <i>n</i> be the significand, exponent and
250 * length of <i>d</i><sub><i>m</i></sub>, respectively.
251 * Further, let <i>e</i> = <i>n</i> + <i>i</i> - 1 and let
252 * <i>s</i><sub>1</sub>…<i>s</i><sub><i>n</i></sub>
253 * be the usual decimal expansion of <i>s</i>.
254 * Note that <i>s</i><sub>1</sub> ≠ 0
255 * and <i>s</i><sub><i>n</i></sub> ≠ 0.
256 * Below, the decimal point {@code '.'} is {@code '\u005Cu002E'}
257 * and the exponent indicator {@code 'E'} is {@code '\u005Cu0045'}.
258 * <ul>
259 * <li>Case -3 ≤ <i>e</i> < 0:
260 * <i>d</i><sub><i>m</i></sub> is formatted as
261 * <code>0.0</code>…<code>0</code><!--
262 * --><i>s</i><sub>1</sub>…<i>s</i><sub><i>n</i></sub>,
263 * where there are exactly -(<i>n</i> + <i>i</i>) zeroes between
264 * the decimal point and <i>s</i><sub>1</sub>.
265 * For example, 123 × 10<sup>-4</sup> is formatted as
266 * {@code 0.0123}.
267 * <li>Case 0 ≤ <i>e</i> < 7:
268 * <ul>
269 * <li>Subcase <i>i</i> ≥ 0:
270 * <i>d</i><sub><i>m</i></sub> is formatted as
271 * <i>s</i><sub>1</sub>…<i>s</i><sub><i>n</i></sub><!--
272 * --><code>0</code>…<code>0.0</code>,
273 * where there are exactly <i>i</i> zeroes
274 * between <i>s</i><sub><i>n</i></sub> and the decimal point.
275 * For example, 123 × 10<sup>2</sup> is formatted as
276 * {@code 12300.0}.
277 * <li>Subcase <i>i</i> < 0:
278 * <i>d</i><sub><i>m</i></sub> is formatted as
279 * <i>s</i><sub>1</sub>…<!--
280 * --><i>s</i><sub><i>n</i>+<i>i</i></sub><code>.</code><!--
281 * --><i>s</i><sub><i>n</i>+<i>i</i>+1</sub>…<!--
282 * --><i>s</i><sub><i>n</i></sub>,
283 * where there are exactly -<i>i</i> digits to the right of
284 * the decimal point.
285 * For example, 123 × 10<sup>-1</sup> is formatted as
286 * {@code 12.3}.
287 * </ul>
288 * <li>Case <i>e</i> < -3 or <i>e</i> ≥ 7:
289 * computerized scientific notation is used to format
290 * <i>d</i><sub><i>m</i></sub>.
291 * Here <i>e</i> is formatted as by {@link Integer#toString(int)}.
292 * <ul>
293 * <li>Subcase <i>n</i> = 1:
294 * <i>d</i><sub><i>m</i></sub> is formatted as
295 * <i>s</i><sub>1</sub><code>.0E</code><i>e</i>.
296 * For example, 1 × 10<sup>23</sup> is formatted as
297 * {@code 1.0E23}.
298 * <li>Subcase <i>n</i> > 1:
299 * <i>d</i><sub><i>m</i></sub> is formatted as
300 * <i>s</i><sub>1</sub><code>.</code><i>s</i><sub>2</sub><!--
301 * -->…<i>s</i><sub><i>n</i></sub><code>E</code><i>e</i>.
302 * For example, 123 × 10<sup>-21</sup> is formatted as
303 * {@code 1.23E-19}.
304 * </ul>
305 * </ul>
306 *
307 * <p>To create localized string representations of a floating-point
308 * value, use subclasses of {@link java.text.NumberFormat}.
309 *
310 * @param f the {@code float} to be converted.
311 * @return a string representation of the argument.
312 */
313 public static String toString(float f) {
314 return FloatToDecimal.toString(f);
315 }
316
317 /**
318 * Returns a hexadecimal string representation of the
319 * {@code float} argument. All characters mentioned below are
320 * ASCII characters.
321 *
322 * <ul>
323 * <li>If the argument is NaN, the result is the string
324 * "{@code NaN}".
325 * <li>Otherwise, the result is a string that represents the sign and
326 * magnitude (absolute value) of the argument. If the sign is negative,
327 * the first character of the result is '{@code -}'
328 * ({@code '\u005Cu002D'}); if the sign is positive, no sign character
329 * appears in the result. As for the magnitude <i>m</i>:
330 *
331 * <ul>
332 * <li>If <i>m</i> is infinity, it is represented by the string
333 * {@code "Infinity"}; thus, positive infinity produces the
334 * result {@code "Infinity"} and negative infinity produces
335 * the result {@code "-Infinity"}.
336 *
337 * <li>If <i>m</i> is zero, it is represented by the string
338 * {@code "0x0.0p0"}; thus, negative zero produces the result
339 * {@code "-0x0.0p0"} and positive zero produces the result
340 * {@code "0x0.0p0"}.
341 *
342 * <li>If <i>m</i> is a {@code float} value with a
343 * normalized representation, substrings are used to represent the
344 * significand and exponent fields. The significand is
345 * represented by the characters {@code "0x1."}
346 * followed by a lowercase hexadecimal representation of the rest
347 * of the significand as a fraction. Trailing zeros in the
348 * hexadecimal representation are removed unless all the digits
349 * are zero, in which case a single zero is used. Next, the
350 * exponent is represented by {@code "p"} followed
351 * by a decimal string of the unbiased exponent as if produced by
352 * a call to {@link Integer#toString(int) Integer.toString} on the
353 * exponent value.
354 *
355 * <li>If <i>m</i> is a {@code float} value with a subnormal
356 * representation, the significand is represented by the
357 * characters {@code "0x0."} followed by a
358 * hexadecimal representation of the rest of the significand as a
359 * fraction. Trailing zeros in the hexadecimal representation are
360 * removed. Next, the exponent is represented by
361 * {@code "p-126"}. Note that there must be at
362 * least one nonzero digit in a subnormal significand.
363 *
364 * </ul>
365 *
366 * </ul>
367 *
368 * <table class="striped">
369 * <caption>Examples</caption>
370 * <thead>
371 * <tr><th scope="col">Floating-point Value</th><th scope="col">Hexadecimal String</th>
372 * </thead>
373 * <tbody>
374 * <tr><th scope="row">{@code 1.0}</th> <td>{@code 0x1.0p0}</td>
375 * <tr><th scope="row">{@code -1.0}</th> <td>{@code -0x1.0p0}</td>
376 * <tr><th scope="row">{@code 2.0}</th> <td>{@code 0x1.0p1}</td>
377 * <tr><th scope="row">{@code 3.0}</th> <td>{@code 0x1.8p1}</td>
378 * <tr><th scope="row">{@code 0.5}</th> <td>{@code 0x1.0p-1}</td>
379 * <tr><th scope="row">{@code 0.25}</th> <td>{@code 0x1.0p-2}</td>
380 * <tr><th scope="row">{@code Float.MAX_VALUE}</th>
381 * <td>{@code 0x1.fffffep127}</td>
382 * <tr><th scope="row">{@code Minimum Normal Value}</th>
383 * <td>{@code 0x1.0p-126}</td>
384 * <tr><th scope="row">{@code Maximum Subnormal Value}</th>
385 * <td>{@code 0x0.fffffep-126}</td>
386 * <tr><th scope="row">{@code Float.MIN_VALUE}</th>
387 * <td>{@code 0x0.000002p-126}</td>
388 * </tbody>
389 * </table>
390 * @param f the {@code float} to be converted.
391 * @return a hex string representation of the argument.
392 * @since 1.5
393 * @author Joseph D. Darcy
394 */
395 public static String toHexString(float f) {
396 if (Math.abs(f) < Float.MIN_NORMAL
397 && f != 0.0f ) {// float subnormal
398 // Adjust exponent to create subnormal double, then
399 // replace subnormal double exponent with subnormal float
400 // exponent
401 String s = Double.toHexString(Math.scalb((double)f,
402 /* -1022+126 */
403 Double.MIN_EXPONENT-
404 Float.MIN_EXPONENT));
405 return s.replaceFirst("p-1022$", "p-126");
406 }
407 else // double string will be the same as float string
408 return Double.toHexString(f);
409 }
410
411 /**
412 * Returns a {@code Float} object holding the
413 * {@code float} value represented by the argument string
414 * {@code s}.
415 *
416 * <p>If {@code s} is {@code null}, then a
417 * {@code NullPointerException} is thrown.
418 *
419 * <p>Leading and trailing whitespace characters in {@code s}
420 * are ignored. Whitespace is removed as if by the {@link
421 * String#trim} method; that is, both ASCII space and control
422 * characters are removed. The rest of {@code s} should
423 * constitute a <i>FloatValue</i> as described by the lexical
424 * syntax rules:
425 *
426 * <blockquote>
427 * <dl>
428 * <dt><i>FloatValue:</i>
429 * <dd><i>Sign<sub>opt</sub></i> {@code NaN}
430 * <dd><i>Sign<sub>opt</sub></i> {@code Infinity}
431 * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
432 * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
433 * <dd><i>SignedInteger</i>
434 * </dl>
435 *
436 * <dl>
437 * <dt><i>HexFloatingPointLiteral</i>:
438 * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
439 * </dl>
440 *
441 * <dl>
442 * <dt><i>HexSignificand:</i>
443 * <dd><i>HexNumeral</i>
444 * <dd><i>HexNumeral</i> {@code .}
445 * <dd>{@code 0x} <i>HexDigits<sub>opt</sub>
446 * </i>{@code .}<i> HexDigits</i>
447 * <dd>{@code 0X}<i> HexDigits<sub>opt</sub>
448 * </i>{@code .} <i>HexDigits</i>
449 * </dl>
450 *
451 * <dl>
452 * <dt><i>BinaryExponent:</i>
453 * <dd><i>BinaryExponentIndicator SignedInteger</i>
454 * </dl>
455 *
456 * <dl>
457 * <dt><i>BinaryExponentIndicator:</i>
458 * <dd>{@code p}
459 * <dd>{@code P}
460 * </dl>
461 *
462 * </blockquote>
463 *
464 * where <i>Sign</i>, <i>FloatingPointLiteral</i>,
465 * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
466 * <i>FloatTypeSuffix</i> are as defined in the lexical structure
467 * sections of
468 * <cite>The Java Language Specification</cite>,
469 * except that underscores are not accepted between digits.
470 * If {@code s} does not have the form of
471 * a <i>FloatValue</i>, then a {@code NumberFormatException}
472 * is thrown. Otherwise, {@code s} is regarded as
473 * representing an exact decimal value in the usual
474 * "computerized scientific notation" or as an exact
475 * hexadecimal value; this exact numerical value is then
476 * conceptually converted to an "infinitely precise"
477 * binary value that is then rounded to type {@code float}
478 * by the usual round-to-nearest rule of IEEE 754 floating-point
479 * arithmetic, which includes preserving the sign of a zero
480 * value.
481 *
482 * Note that the round-to-nearest rule also implies overflow and
483 * underflow behaviour; if the exact value of {@code s} is large
484 * enough in magnitude (greater than or equal to ({@link
485 * #MAX_VALUE} + {@link Math#ulp(float) ulp(MAX_VALUE)}/2),
486 * rounding to {@code float} will result in an infinity and if the
487 * exact value of {@code s} is small enough in magnitude (less
488 * than or equal to {@link #MIN_VALUE}/2), rounding to float will
489 * result in a zero.
490 *
491 * Finally, after rounding a {@code Float} object representing
492 * this {@code float} value is returned.
493 *
494 * <p>Note that trailing format specifiers, specifiers that
495 * determine the type of a floating-point literal
496 * ({@code 1.0f} is a {@code float} value;
497 * {@code 1.0d} is a {@code double} value), do
498 * <em>not</em> influence the results of this method. In other
499 * words, the numerical value of the input string is converted
500 * directly to the target floating-point type. In general, the
501 * two-step sequence of conversions, string to {@code double}
502 * followed by {@code double} to {@code float}, is
503 * <em>not</em> equivalent to converting a string directly to
504 * {@code float}. For example, if first converted to an
505 * intermediate {@code double} and then to
506 * {@code float}, the string<br>
507 * {@code "1.00000017881393421514957253748434595763683319091796875001d"}<br>
508 * results in the {@code float} value
509 * {@code 1.0000002f}; if the string is converted directly to
510 * {@code float}, <code>1.000000<b>1</b>f</code> results.
511 *
512 * <p>To avoid calling this method on an invalid string and having
513 * a {@code NumberFormatException} be thrown, the documentation
514 * for {@link Double#valueOf Double.valueOf} lists a regular
515 * expression which can be used to screen the input.
516 *
517 * @apiNote To interpret localized string representations of a
518 * floating-point value, or string representations that have
519 * non-ASCII digits, use {@link java.text.NumberFormat}. For
520 * example,
521 * {@snippet lang="java" :
522 * NumberFormat.getInstance(l).parse(s).floatValue();
523 * }
524 * where {@code l} is the desired locale, or
525 * {@link java.util.Locale#ROOT} if locale insensitive.
526 *
527 * @param s the string to be parsed.
528 * @return a {@code Float} object holding the value
529 * represented by the {@code String} argument.
530 * @throws NumberFormatException if the string does not contain a
531 * parsable number.
532 * @see Double##decimalToBinaryConversion Decimal ↔ Binary Conversion Issues
533 */
534 public static Float valueOf(String s) throws NumberFormatException {
535 return new Float(parseFloat(s));
536 }
537
538 /**
539 * Returns a {@code Float} instance representing the specified
540 * {@code float} value.
541 * If a new {@code Float} instance is not required, this method
542 * should generally be used in preference to the constructor
543 * {@link #Float(float)}, as this method is likely to yield
544 * significantly better space and time performance by caching
545 * frequently requested values.
546 *
547 * @param f a float value.
548 * @return a {@code Float} instance representing {@code f}.
549 * @since 1.5
550 */
551 @IntrinsicCandidate
552 public static Float valueOf(float f) {
553 return new Float(f);
554 }
555
556 /**
557 * Returns a new {@code float} initialized to the value
558 * represented by the specified {@code String}, as performed
559 * by the {@code valueOf} method of class {@code Float}.
560 *
561 * @param s the string to be parsed.
562 * @return the {@code float} value represented by the string
563 * argument.
564 * @throws NullPointerException if the string is null
565 * @throws NumberFormatException if the string does not contain a
566 * parsable {@code float}.
567 * @see java.lang.Float#valueOf(String)
568 * @see Double##decimalToBinaryConversion Decimal ↔ Binary Conversion Issues
569 * @since 1.2
570 */
571 public static float parseFloat(String s) throws NumberFormatException {
572 return FloatingDecimal.parseFloat(s);
573 }
574
575 /**
576 * Returns {@code true} if the specified number is a
577 * Not-a-Number (NaN) value, {@code false} otherwise.
578 *
579 * @apiNote
580 * This method corresponds to the isNaN operation defined in IEEE
581 * 754.
582 *
583 * @param v the value to be tested.
584 * @return {@code true} if the argument is NaN;
585 * {@code false} otherwise.
586 */
587 public static boolean isNaN(float v) {
588 return (v != v);
589 }
590
591 /**
592 * Returns {@code true} if the specified number is infinitely
593 * large in magnitude, {@code false} otherwise.
594 *
595 * @apiNote
596 * This method corresponds to the isInfinite operation defined in
597 * IEEE 754.
598 *
599 * @param v the value to be tested.
600 * @return {@code true} if the argument is positive infinity or
601 * negative infinity; {@code false} otherwise.
602 */
603 @IntrinsicCandidate
604 public static boolean isInfinite(float v) {
605 return Math.abs(v) > MAX_VALUE;
606 }
607
608
609 /**
610 * Returns {@code true} if the argument is a finite floating-point
611 * value; returns {@code false} otherwise (for NaN and infinity
612 * arguments).
613 *
614 * @apiNote
615 * This method corresponds to the isFinite operation defined in
616 * IEEE 754.
617 *
618 * @param f the {@code float} value to be tested
619 * @return {@code true} if the argument is a finite
620 * floating-point value, {@code false} otherwise.
621 * @since 1.8
622 */
623 @IntrinsicCandidate
624 public static boolean isFinite(float f) {
625 return Math.abs(f) <= Float.MAX_VALUE;
626 }
627
628 /**
629 * The value of the Float.
630 *
631 * @serial
632 */
633 private final float value;
634
635 /**
636 * Constructs a newly allocated {@code Float} object that
637 * represents the primitive {@code float} argument.
638 *
639 * @param value the value to be represented by the {@code Float}.
640 *
641 * @deprecated
642 * It is rarely appropriate to use this constructor. The static factory
643 * {@link #valueOf(float)} is generally a better choice, as it is
644 * likely to yield significantly better space and time performance.
645 */
646 @Deprecated(since="9", forRemoval = true)
647 public Float(float value) {
648 this.value = value;
649 }
650
651 /**
652 * Constructs a newly allocated {@code Float} object that
653 * represents the argument converted to type {@code float}.
654 *
655 * @param value the value to be represented by the {@code Float}.
656 *
657 * @deprecated
658 * It is rarely appropriate to use this constructor. Instead, use the
659 * static factory method {@link #valueOf(float)} method as follows:
660 * {@code Float.valueOf((float)value)}.
661 */
662 @Deprecated(since="9", forRemoval = true)
663 public Float(double value) {
664 this.value = (float)value;
665 }
666
667 /**
668 * Constructs a newly allocated {@code Float} object that
669 * represents the floating-point value of type {@code float}
670 * represented by the string. The string is converted to a
671 * {@code float} value as if by the {@code valueOf} method.
672 *
673 * @param s a string to be converted to a {@code Float}.
674 * @throws NumberFormatException if the string does not contain a
675 * parsable number.
676 *
677 * @deprecated
678 * It is rarely appropriate to use this constructor.
679 * Use {@link #parseFloat(String)} to convert a string to a
680 * {@code float} primitive, or use {@link #valueOf(String)}
681 * to convert a string to a {@code Float} object.
682 */
683 @Deprecated(since="9", forRemoval = true)
684 public Float(String s) throws NumberFormatException {
685 value = parseFloat(s);
686 }
687
688 /**
689 * Returns {@code true} if this {@code Float} value is a
690 * Not-a-Number (NaN), {@code false} otherwise.
691 *
692 * @return {@code true} if the value represented by this object is
693 * NaN; {@code false} otherwise.
694 */
695 public boolean isNaN() {
696 return isNaN(value);
697 }
698
699 /**
700 * Returns {@code true} if this {@code Float} value is
701 * infinitely large in magnitude, {@code false} otherwise.
702 *
703 * @return {@code true} if the value represented by this object is
704 * positive infinity or negative infinity;
705 * {@code false} otherwise.
706 */
707 public boolean isInfinite() {
708 return isInfinite(value);
709 }
710
711 /**
712 * Returns a string representation of this {@code Float} object.
713 * The primitive {@code float} value represented by this object
714 * is converted to a {@code String} exactly as if by the method
715 * {@code toString} of one argument.
716 *
717 * @return a {@code String} representation of this object.
718 * @see java.lang.Float#toString(float)
719 */
720 public String toString() {
721 return Float.toString(value);
722 }
723
724 /**
725 * Returns the value of this {@code Float} as a {@code byte} after
726 * a narrowing primitive conversion.
727 *
728 * @return the {@code float} value represented by this object
729 * converted to type {@code byte}
730 * @jls 5.1.3 Narrowing Primitive Conversion
731 */
732 public byte byteValue() {
733 return (byte)value;
734 }
735
736 /**
737 * Returns the value of this {@code Float} as a {@code short}
738 * after a narrowing primitive conversion.
739 *
740 * @return the {@code float} value represented by this object
741 * converted to type {@code short}
742 * @jls 5.1.3 Narrowing Primitive Conversion
743 * @since 1.1
744 */
745 public short shortValue() {
746 return (short)value;
747 }
748
749 /**
750 * Returns the value of this {@code Float} as an {@code int} after
751 * a narrowing primitive conversion.
752 *
753 * @return the {@code float} value represented by this object
754 * converted to type {@code int}
755 * @jls 5.1.3 Narrowing Primitive Conversion
756 */
757 public int intValue() {
758 return (int)value;
759 }
760
761 /**
762 * Returns value of this {@code Float} as a {@code long} after a
763 * narrowing primitive conversion.
764 *
765 * @return the {@code float} value represented by this object
766 * converted to type {@code long}
767 * @jls 5.1.3 Narrowing Primitive Conversion
768 */
769 public long longValue() {
770 return (long)value;
771 }
772
773 /**
774 * Returns the {@code float} value of this {@code Float} object.
775 *
776 * @return the {@code float} value represented by this object
777 */
778 @IntrinsicCandidate
779 public float floatValue() {
780 return value;
781 }
782
783 /**
784 * Returns the value of this {@code Float} as a {@code double}
785 * after a widening primitive conversion.
786 *
787 * @apiNote
788 * This method corresponds to the convertFormat operation defined
789 * in IEEE 754.
790 *
791 * @return the {@code float} value represented by this
792 * object converted to type {@code double}
793 * @jls 5.1.2 Widening Primitive Conversion
794 */
795 public double doubleValue() {
796 return (double)value;
797 }
798
799 /**
800 * Returns a hash code for this {@code Float} object. The
801 * result is the integer bit representation, exactly as produced
802 * by the method {@link #floatToIntBits(float)}, of the primitive
803 * {@code float} value represented by this {@code Float}
804 * object.
805 *
806 * @return a hash code value for this object.
807 */
808 @Override
809 public int hashCode() {
810 return Float.hashCode(value);
811 }
812
813 /**
814 * Returns a hash code for a {@code float} value; compatible with
815 * {@code Float.hashCode()}.
816 *
817 * @param value the value to hash
818 * @return a hash code value for a {@code float} value.
819 * @since 1.8
820 */
821 public static int hashCode(float value) {
822 return floatToIntBits(value);
823 }
824
825 /**
826 * Compares this object against the specified object. The result
827 * is {@code true} if and only if the argument is not
828 * {@code null} and is a {@code Float} object that
829 * represents a {@code float} with the same value as the
830 * {@code float} represented by this object. For this
831 * purpose, two {@code float} values are considered to be the
832 * same if and only if the method {@link #floatToIntBits(float)}
833 * returns the identical {@code int} value when applied to
834 * each.
835 *
836 * @apiNote
837 * This method is defined in terms of {@link
838 * #floatToIntBits(float)} rather than the {@code ==} operator on
839 * {@code float} values since the {@code ==} operator does
840 * <em>not</em> define an equivalence relation and to satisfy the
841 * {@linkplain Object#equals equals contract} an equivalence
842 * relation must be implemented; see <a
843 * href="Double.html#equivalenceRelation">this discussion</a> for
844 * details of floating-point equality and equivalence.
845 *
846 * @param obj the object to be compared
847 * @return {@code true} if the objects are the same;
848 * {@code false} otherwise.
849 * @see java.lang.Float#floatToIntBits(float)
850 * @jls 15.21.1 Numerical Equality Operators == and !=
851 */
852 public boolean equals(Object obj) {
853 return (obj instanceof Float)
854 && (floatToIntBits(((Float)obj).value) == floatToIntBits(value));
855 }
856
857 /**
858 * Returns a representation of the specified floating-point value
859 * according to the IEEE 754 floating-point "single format" bit
860 * layout.
861 *
862 * <p>Bit 31 (the bit that is selected by the mask
863 * {@code 0x80000000}) represents the sign of the floating-point
864 * number.
865 * Bits 30-23 (the bits that are selected by the mask
866 * {@code 0x7f800000}) represent the exponent.
867 * Bits 22-0 (the bits that are selected by the mask
868 * {@code 0x007fffff}) represent the significand (sometimes called
869 * the mantissa) of the floating-point number.
870 *
871 * <p>If the argument is positive infinity, the result is
872 * {@code 0x7f800000}.
873 *
874 * <p>If the argument is negative infinity, the result is
875 * {@code 0xff800000}.
876 *
877 * <p>If the argument is NaN, the result is {@code 0x7fc00000}.
878 *
879 * <p>In all cases, the result is an integer that, when given to the
880 * {@link #intBitsToFloat(int)} method, will produce a floating-point
881 * value the same as the argument to {@code floatToIntBits}
882 * (except all NaN values are collapsed to a single
883 * "canonical" NaN value).
884 *
885 * @param value a floating-point number.
886 * @return the bits that represent the floating-point number.
887 */
888 @IntrinsicCandidate
889 public static int floatToIntBits(float value) {
890 if (!isNaN(value)) {
891 return floatToRawIntBits(value);
892 }
893 return 0x7fc00000;
894 }
895
896 /**
897 * Returns a representation of the specified floating-point value
898 * according to the IEEE 754 floating-point "single format" bit
899 * layout, preserving Not-a-Number (NaN) values.
900 *
901 * <p>Bit 31 (the bit that is selected by the mask
902 * {@code 0x80000000}) represents the sign of the floating-point
903 * number.
904 * Bits 30-23 (the bits that are selected by the mask
905 * {@code 0x7f800000}) represent the exponent.
906 * Bits 22-0 (the bits that are selected by the mask
907 * {@code 0x007fffff}) represent the significand (sometimes called
908 * the mantissa) of the floating-point number.
909 *
910 * <p>If the argument is positive infinity, the result is
911 * {@code 0x7f800000}.
912 *
913 * <p>If the argument is negative infinity, the result is
914 * {@code 0xff800000}.
915 *
916 * <p>If the argument is NaN, the result is the integer representing
917 * the actual NaN value. Unlike the {@code floatToIntBits}
918 * method, {@code floatToRawIntBits} does not collapse all the
919 * bit patterns encoding a NaN to a single "canonical"
920 * NaN value.
921 *
922 * <p>In all cases, the result is an integer that, when given to the
923 * {@link #intBitsToFloat(int)} method, will produce a
924 * floating-point value the same as the argument to
925 * {@code floatToRawIntBits}.
926 *
927 * @param value a floating-point number.
928 * @return the bits that represent the floating-point number.
929 * @since 1.3
930 */
931 @IntrinsicCandidate
932 public static native int floatToRawIntBits(float value);
933
934 /**
935 * Returns the {@code float} value corresponding to a given
936 * bit representation.
937 * The argument is considered to be a representation of a
938 * floating-point value according to the IEEE 754 floating-point
939 * "single format" bit layout.
940 *
941 * <p>If the argument is {@code 0x7f800000}, the result is positive
942 * infinity.
943 *
944 * <p>If the argument is {@code 0xff800000}, the result is negative
945 * infinity.
946 *
947 * <p>If the argument is any value in the range
948 * {@code 0x7f800001} through {@code 0x7fffffff} or in
949 * the range {@code 0xff800001} through
950 * {@code 0xffffffff}, the result is a NaN. No IEEE 754
951 * floating-point operation provided by Java can distinguish
952 * between two NaN values of the same type with different bit
953 * patterns. Distinct values of NaN are only distinguishable by
954 * use of the {@code Float.floatToRawIntBits} method.
955 *
956 * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
957 * values that can be computed from the argument:
958 *
959 * {@snippet lang="java" :
960 * int s = ((bits >> 31) == 0) ? 1 : -1;
961 * int e = ((bits >> 23) & 0xff);
962 * int m = (e == 0) ?
963 * (bits & 0x7fffff) << 1 :
964 * (bits & 0x7fffff) | 0x800000;
965 * }
966 *
967 * Then the floating-point result equals the value of the mathematical
968 * expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-150</sup>.
969 *
970 * <p>Note that this method may not be able to return a
971 * {@code float} NaN with exactly same bit pattern as the
972 * {@code int} argument. IEEE 754 distinguishes between two
973 * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The
974 * differences between the two kinds of NaN are generally not
975 * visible in Java. Arithmetic operations on signaling NaNs turn
976 * them into quiet NaNs with a different, but often similar, bit
977 * pattern. However, on some processors merely copying a
978 * signaling NaN also performs that conversion. In particular,
979 * copying a signaling NaN to return it to the calling method may
980 * perform this conversion. So {@code intBitsToFloat} may
981 * not be able to return a {@code float} with a signaling NaN
982 * bit pattern. Consequently, for some {@code int} values,
983 * {@code floatToRawIntBits(intBitsToFloat(start))} may
984 * <i>not</i> equal {@code start}. Moreover, which
985 * particular bit patterns represent signaling NaNs is platform
986 * dependent; although all NaN bit patterns, quiet or signaling,
987 * must be in the NaN range identified above.
988 *
989 * @param bits an integer.
990 * @return the {@code float} floating-point value with the same bit
991 * pattern.
992 */
993 @IntrinsicCandidate
994 public static native float intBitsToFloat(int bits);
995
996 /**
997 * {@return the {@code float} value closest to the numerical value
998 * of the argument, a floating-point binary16 value encoded in a
999 * {@code short}} The conversion is exact; all binary16 values can
1000 * be exactly represented in {@code float}.
1001 *
1002 * Special cases:
1003 * <ul>
1004 * <li> If the argument is zero, the result is a zero with the
1005 * same sign as the argument.
1006 * <li> If the argument is infinite, the result is an infinity
1007 * with the same sign as the argument.
1008 * <li> If the argument is a NaN, the result is a NaN.
1009 * </ul>
1010 *
1011 * <h4><a id=binary16Format>IEEE 754 binary16 format</a></h4>
1012 * The IEEE 754 standard defines binary16 as a 16-bit format, along
1013 * with the 32-bit binary32 format (corresponding to the {@code
1014 * float} type) and the 64-bit binary64 format (corresponding to
1015 * the {@code double} type). The binary16 format is similar to the
1016 * other IEEE 754 formats, except smaller, having all the usual
1017 * IEEE 754 values such as NaN, signed infinities, signed zeros,
1018 * and subnormals. The parameters (JLS {@jls 4.2.3}) for the
1019 * binary16 format are N = 11 precision bits, K = 5 exponent bits,
1020 * <i>E</i><sub><i>max</i></sub> = 15, and
1021 * <i>E</i><sub><i>min</i></sub> = -14.
1022 *
1023 * @apiNote
1024 * This method corresponds to the convertFormat operation defined
1025 * in IEEE 754 from the binary16 format to the binary32 format.
1026 * The operation of this method is analogous to a primitive
1027 * widening conversion (JLS {@jls 5.1.2}).
1028 *
1029 * @param floatBinary16 the binary16 value to convert to {@code float}
1030 * @since 20
1031 */
1032 @IntrinsicCandidate
1033 public static float float16ToFloat(short floatBinary16) {
1034 /*
1035 * The binary16 format has 1 sign bit, 5 exponent bits, and 10
1036 * significand bits. The exponent bias is 15.
1037 */
1038 int bin16arg = (int)floatBinary16;
1039 int bin16SignBit = 0x8000 & bin16arg;
1040 int bin16ExpBits = 0x7c00 & bin16arg;
1041 int bin16SignifBits = 0x03FF & bin16arg;
1042
1043 // Shift left difference in the number of significand bits in
1044 // the float and binary16 formats
1045 final int SIGNIF_SHIFT = (FloatConsts.SIGNIFICAND_WIDTH - 11);
1046
1047 float sign = (bin16SignBit != 0) ? -1.0f : 1.0f;
1048
1049 // Extract binary16 exponent, remove its bias, add in the bias
1050 // of a float exponent and shift to correct bit location
1051 // (significand width includes the implicit bit so shift one
1052 // less).
1053 int bin16Exp = (bin16ExpBits >> 10) - 15;
1054 if (bin16Exp == -15) {
1055 // For subnormal binary16 values and 0, the numerical
1056 // value is 2^24 * the significand as an integer (no
1057 // implicit bit).
1058 return sign * (0x1p-24f * bin16SignifBits);
1059 } else if (bin16Exp == 16) {
1060 return (bin16SignifBits == 0) ?
1061 sign * Float.POSITIVE_INFINITY :
1062 Float.intBitsToFloat((bin16SignBit << 16) |
1063 0x7f80_0000 |
1064 // Preserve NaN signif bits
1065 ( bin16SignifBits << SIGNIF_SHIFT ));
1066 }
1067
1068 assert -15 < bin16Exp && bin16Exp < 16;
1069
1070 int floatExpBits = (bin16Exp + FloatConsts.EXP_BIAS)
1071 << (FloatConsts.SIGNIFICAND_WIDTH - 1);
1072
1073 // Compute and combine result sign, exponent, and significand bits.
1074 return Float.intBitsToFloat((bin16SignBit << 16) |
1075 floatExpBits |
1076 (bin16SignifBits << SIGNIF_SHIFT));
1077 }
1078
1079 /**
1080 * {@return the floating-point binary16 value, encoded in a {@code
1081 * short}, closest in value to the argument}
1082 * The conversion is computed under the {@linkplain
1083 * java.math.RoundingMode#HALF_EVEN round to nearest even rounding
1084 * mode}.
1085 *
1086 * Special cases:
1087 * <ul>
1088 * <li> If the argument is zero, the result is a zero with the
1089 * same sign as the argument.
1090 * <li> If the argument is infinite, the result is an infinity
1091 * with the same sign as the argument.
1092 * <li> If the argument is a NaN, the result is a NaN.
1093 * </ul>
1094 *
1095 * The <a href="#binary16Format">binary16 format</a> is discussed in
1096 * more detail in the {@link #float16ToFloat} method.
1097 *
1098 * @apiNote
1099 * This method corresponds to the convertFormat operation defined
1100 * in IEEE 754 from the binary32 format to the binary16 format.
1101 * The operation of this method is analogous to a primitive
1102 * narrowing conversion (JLS {@jls 5.1.3}).
1103 *
1104 * @param f the {@code float} value to convert to binary16
1105 * @since 20
1106 */
1107 @IntrinsicCandidate
1108 public static short floatToFloat16(float f) {
1109 int doppel = Float.floatToRawIntBits(f);
1110 short sign_bit = (short)((doppel & 0x8000_0000) >> 16);
1111
1112 if (Float.isNaN(f)) {
1113 // Preserve sign and attempt to preserve significand bits
1114 return (short)(sign_bit
1115 | 0x7c00 // max exponent + 1
1116 // Preserve high order bit of float NaN in the
1117 // binary16 result NaN (tenth bit); OR in remaining
1118 // bits into lower 9 bits of binary 16 significand.
1119 | (doppel & 0x007f_e000) >> 13 // 10 bits
1120 | (doppel & 0x0000_1ff0) >> 4 // 9 bits
1121 | (doppel & 0x0000_000f)); // 4 bits
1122 }
1123
1124 float abs_f = Math.abs(f);
1125
1126 // The overflow threshold is binary16 MAX_VALUE + 1/2 ulp
1127 if (abs_f >= (0x1.ffcp15f + 0x0.002p15f) ) {
1128 return (short)(sign_bit | 0x7c00); // Positive or negative infinity
1129 }
1130
1131 // Smallest magnitude nonzero representable binary16 value
1132 // is equal to 0x1.0p-24; half-way and smaller rounds to zero.
1133 if (abs_f <= 0x1.0p-24f * 0.5f) { // Covers float zeros and subnormals.
1134 return sign_bit; // Positive or negative zero
1135 }
1136
1137 // Dealing with finite values in exponent range of binary16
1138 // (when rounding is done, could still round up)
1139 int exp = Math.getExponent(f);
1140 assert -25 <= exp && exp <= 15;
1141
1142 // For binary16 subnormals, beside forcing exp to -15, retain
1143 // the difference expdelta = E_min - exp. This is the excess
1144 // shift value, in addition to 13, to be used in the
1145 // computations below. Further the (hidden) msb with value 1
1146 // in f must be involved as well.
1147 int expdelta = 0;
1148 int msb = 0x0000_0000;
1149 if (exp < -14) {
1150 expdelta = -14 - exp;
1151 exp = -15;
1152 msb = 0x0080_0000;
1153 }
1154 int f_signif_bits = doppel & 0x007f_ffff | msb;
1155
1156 // Significand bits as if using rounding to zero (truncation).
1157 short signif_bits = (short)(f_signif_bits >> (13 + expdelta));
1158
1159 // For round to nearest even, determining whether or not to
1160 // round up (in magnitude) is a function of the least
1161 // significant bit (LSB), the next bit position (the round
1162 // position), and the sticky bit (whether there are any
1163 // nonzero bits in the exact result to the right of the round
1164 // digit). An increment occurs in three cases:
1165 //
1166 // LSB Round Sticky
1167 // 0 1 1
1168 // 1 1 0
1169 // 1 1 1
1170 // See "Computer Arithmetic Algorithms," Koren, Table 4.9
1171
1172 int lsb = f_signif_bits & (1 << 13 + expdelta);
1173 int round = f_signif_bits & (1 << 12 + expdelta);
1174 int sticky = f_signif_bits & ((1 << 12 + expdelta) - 1);
1175
1176 if (round != 0 && ((lsb | sticky) != 0 )) {
1177 signif_bits++;
1178 }
1179
1180 // No bits set in significand beyond the *first* exponent bit,
1181 // not just the significand; quantity is added to the exponent
1182 // to implement a carry out from rounding the significand.
1183 assert (0xf800 & signif_bits) == 0x0;
1184
1185 return (short)(sign_bit | ( ((exp + 15) << 10) + signif_bits ) );
1186 }
1187
1188 /**
1189 * Compares two {@code Float} objects numerically.
1190 *
1191 * This method imposes a total order on {@code Float} objects
1192 * with two differences compared to the incomplete order defined by
1193 * the Java language numerical comparison operators ({@code <, <=,
1194 * ==, >=, >}) on {@code float} values.
1195 *
1196 * <ul><li> A NaN is <em>unordered</em> with respect to other
1197 * values and unequal to itself under the comparison
1198 * operators. This method chooses to define {@code
1199 * Float.NaN} to be equal to itself and greater than all
1200 * other {@code double} values (including {@code
1201 * Float.POSITIVE_INFINITY}).
1202 *
1203 * <li> Positive zero and negative zero compare equal
1204 * numerically, but are distinct and distinguishable values.
1205 * This method chooses to define positive zero ({@code +0.0f}),
1206 * to be greater than negative zero ({@code -0.0f}).
1207 * </ul>
1208 *
1209 * This ensures that the <i>natural ordering</i> of {@code Float}
1210 * objects imposed by this method is <i>consistent with
1211 * equals</i>; see <a href="Double.html#equivalenceRelation">this
1212 * discussion</a> for details of floating-point comparison and
1213 * ordering.
1214 *
1215 *
1216 * @param anotherFloat the {@code Float} to be compared.
1217 * @return the value {@code 0} if {@code anotherFloat} is
1218 * numerically equal to this {@code Float}; a value
1219 * less than {@code 0} if this {@code Float}
1220 * is numerically less than {@code anotherFloat};
1221 * and a value greater than {@code 0} if this
1222 * {@code Float} is numerically greater than
1223 * {@code anotherFloat}.
1224 *
1225 * @jls 15.20.1 Numerical Comparison Operators {@code <}, {@code <=}, {@code >}, and {@code >=}
1226 * @since 1.2
1227 */
1228 public int compareTo(Float anotherFloat) {
1229 return Float.compare(value, anotherFloat.value);
1230 }
1231
1232 /**
1233 * Compares the two specified {@code float} values. The sign
1234 * of the integer value returned is the same as that of the
1235 * integer that would be returned by the call:
1236 * <pre>
1237 * Float.valueOf(f1).compareTo(Float.valueOf(f2))
1238 * </pre>
1239 *
1240 * @param f1 the first {@code float} to compare.
1241 * @param f2 the second {@code float} to compare.
1242 * @return the value {@code 0} if {@code f1} is
1243 * numerically equal to {@code f2}; a value less than
1244 * {@code 0} if {@code f1} is numerically less than
1245 * {@code f2}; and a value greater than {@code 0}
1246 * if {@code f1} is numerically greater than
1247 * {@code f2}.
1248 * @since 1.4
1249 */
1250 public static int compare(float f1, float f2) {
1251 if (f1 < f2)
1252 return -1; // Neither val is NaN, thisVal is smaller
1253 if (f1 > f2)
1254 return 1; // Neither val is NaN, thisVal is larger
1255
1256 // Cannot use floatToRawIntBits because of possibility of NaNs.
1257 int thisBits = Float.floatToIntBits(f1);
1258 int anotherBits = Float.floatToIntBits(f2);
1259
1260 return (thisBits == anotherBits ? 0 : // Values are equal
1261 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
1262 1)); // (0.0, -0.0) or (NaN, !NaN)
1263 }
1264
1265 /**
1266 * Adds two {@code float} values together as per the + operator.
1267 *
1268 * @apiNote This method corresponds to the addition operation
1269 * defined in IEEE 754.
1270 *
1271 * @param a the first operand
1272 * @param b the second operand
1273 * @return the sum of {@code a} and {@code b}
1274 * @jls 4.2.4 Floating-Point Operations
1275 * @see java.util.function.BinaryOperator
1276 * @since 1.8
1277 */
1278 public static float sum(float a, float b) {
1279 return a + b;
1280 }
1281
1282 /**
1283 * Returns the greater of two {@code float} values
1284 * as if by calling {@link Math#max(float, float) Math.max}.
1285 *
1286 * @apiNote
1287 * This method corresponds to the maximum operation defined in
1288 * IEEE 754.
1289 *
1290 * @param a the first operand
1291 * @param b the second operand
1292 * @return the greater of {@code a} and {@code b}
1293 * @see java.util.function.BinaryOperator
1294 * @since 1.8
1295 */
1296 public static float max(float a, float b) {
1297 return Math.max(a, b);
1298 }
1299
1300 /**
1301 * Returns the smaller of two {@code float} values
1302 * as if by calling {@link Math#min(float, float) Math.min}.
1303 *
1304 * @apiNote
1305 * This method corresponds to the minimum operation defined in
1306 * IEEE 754.
1307 *
1308 * @param a the first operand
1309 * @param b the second operand
1310 * @return the smaller of {@code a} and {@code b}
1311 * @see java.util.function.BinaryOperator
1312 * @since 1.8
1313 */
1314 public static float min(float a, float b) {
1315 return Math.min(a, b);
1316 }
1317
1318 /**
1319 * Returns an {@link Optional} containing the nominal descriptor for this
1320 * instance, which is the instance itself.
1321 *
1322 * @return an {@link Optional} describing the {@linkplain Float} instance
1323 * @since 12
1324 */
1325 @Override
1326 public Optional<Float> describeConstable() {
1327 return Optional.of(this);
1328 }
1329
1330 /**
1331 * Resolves this instance as a {@link ConstantDesc}, the result of which is
1332 * the instance itself.
1333 *
1334 * @param lookup ignored
1335 * @return the {@linkplain Float} instance
1336 * @since 12
1337 */
1338 @Override
1339 public Float resolveConstantDesc(MethodHandles.Lookup lookup) {
1340 return this;
1341 }
1342
1343 /** use serialVersionUID from JDK 1.0.2 for interoperability */
1344 @java.io.Serial
1345 private static final long serialVersionUID = -2671257302660747028L;
1346 }