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