1 /* 2 * Copyright (c) 1994, 2016, 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.Constable; 29 import java.lang.invoke.MethodHandles; 30 31 import jdk.internal.math.FloatingDecimal; 32 import jdk.internal.HotSpotIntrinsicCandidate; 33 34 /** 35 * The {@code Float} class wraps a value of primitive type 36 * {@code float} in an object. An object of type 37 * {@code Float} contains a single field whose type is 38 * {@code float}. 39 * 40 * <p>In addition, this class provides several methods for converting a 41 * {@code float} to a {@code String} and a 42 * {@code String} to a {@code float}, as well as other 43 * constants and methods useful when dealing with a 44 * {@code float}. 45 * 46 * @author Lee Boynton 47 * @author Arthur van Hoff 48 * @author Joseph D. Darcy 49 * @since 1.0 50 */ 51 public final class Float extends Number implements Comparable<Float>, Constable<Float> { 52 /** 53 * A constant holding the positive infinity of type 54 * {@code float}. It is equal to the value returned by 55 * {@code Float.intBitsToFloat(0x7f800000)}. 56 */ 57 public static final float POSITIVE_INFINITY = 1.0f / 0.0f; 58 59 /** 60 * A constant holding the negative infinity of type 61 * {@code float}. It is equal to the value returned by 62 * {@code Float.intBitsToFloat(0xff800000)}. 63 */ 64 public static final float NEGATIVE_INFINITY = -1.0f / 0.0f; 65 66 /** 67 * A constant holding a Not-a-Number (NaN) value of type 68 * {@code float}. It is equivalent to the value returned by 69 * {@code Float.intBitsToFloat(0x7fc00000)}. 70 */ 71 public static final float NaN = 0.0f / 0.0f; 72 73 /** 74 * A constant holding the largest positive finite value of type 75 * {@code float}, (2-2<sup>-23</sup>)·2<sup>127</sup>. 76 * It is equal to the hexadecimal floating-point literal 77 * {@code 0x1.fffffeP+127f} and also equal to 78 * {@code Float.intBitsToFloat(0x7f7fffff)}. 79 */ 80 public static final float MAX_VALUE = 0x1.fffffeP+127f; // 3.4028235e+38f 81 82 /** 83 * A constant holding the smallest positive normal value of type 84 * {@code float}, 2<sup>-126</sup>. It is equal to the 85 * hexadecimal floating-point literal {@code 0x1.0p-126f} and also 86 * equal to {@code Float.intBitsToFloat(0x00800000)}. 87 * 88 * @since 1.6 89 */ 90 public static final float MIN_NORMAL = 0x1.0p-126f; // 1.17549435E-38f 91 92 /** 93 * A constant holding the smallest positive nonzero value of type 94 * {@code float}, 2<sup>-149</sup>. It is equal to the 95 * hexadecimal floating-point literal {@code 0x0.000002P-126f} 96 * and also equal to {@code Float.intBitsToFloat(0x1)}. 97 */ 98 public static final float MIN_VALUE = 0x0.000002P-126f; // 1.4e-45f 99 100 /** 101 * Maximum exponent a finite {@code float} variable may have. It 102 * is equal to the value returned by {@code 103 * Math.getExponent(Float.MAX_VALUE)}. 104 * 105 * @since 1.6 106 */ 107 public static final int MAX_EXPONENT = 127; 108 109 /** 110 * Minimum exponent a normalized {@code float} variable may have. 111 * It is equal to the value returned by {@code 112 * Math.getExponent(Float.MIN_NORMAL)}. 113 * 114 * @since 1.6 115 */ 116 public static final int MIN_EXPONENT = -126; 117 118 /** 119 * The number of bits used to represent a {@code float} value. 120 * 121 * @since 1.5 122 */ 123 public static final int SIZE = 32; 124 125 /** 126 * The number of bytes used to represent a {@code float} value. 127 * 128 * @since 1.8 129 */ 130 public static final int BYTES = SIZE / Byte.SIZE; 131 132 /** 133 * The {@code Class} instance representing the primitive type 134 * {@code float}. 135 * 136 * @since 1.1 137 */ 138 @SuppressWarnings("unchecked") 139 public static final Class<Float> TYPE = (Class<Float>) Class.getPrimitiveClass("float"); 140 141 /** 142 * Returns a string representation of the {@code float} 143 * argument. All characters mentioned below are ASCII characters. 144 * <ul> 145 * <li>If the argument is NaN, the result is the string 146 * "{@code NaN}". 147 * <li>Otherwise, the result is a string that represents the sign and 148 * magnitude (absolute value) of the argument. If the sign is 149 * negative, the first character of the result is 150 * '{@code -}' ({@code '\u005Cu002D'}); if the sign is 151 * positive, no sign character appears in the result. As for 152 * the magnitude <i>m</i>: 153 * <ul> 154 * <li>If <i>m</i> is infinity, it is represented by the characters 155 * {@code "Infinity"}; thus, positive infinity produces 156 * the result {@code "Infinity"} and negative infinity 157 * produces the result {@code "-Infinity"}. 158 * <li>If <i>m</i> is zero, it is represented by the characters 159 * {@code "0.0"}; thus, negative zero produces the result 160 * {@code "-0.0"} and positive zero produces the result 161 * {@code "0.0"}. 162 * <li> If <i>m</i> is greater than or equal to 10<sup>-3</sup> but 163 * less than 10<sup>7</sup>, then it is represented as the 164 * integer part of <i>m</i>, in decimal form with no leading 165 * zeroes, followed by '{@code .}' 166 * ({@code '\u005Cu002E'}), followed by one or more 167 * decimal digits representing the fractional part of 168 * <i>m</i>. 169 * <li> If <i>m</i> is less than 10<sup>-3</sup> or greater than or 170 * equal to 10<sup>7</sup>, then it is represented in 171 * so-called "computerized scientific notation." Let <i>n</i> 172 * be the unique integer such that 10<sup><i>n</i> </sup>≤ 173 * <i>m</i> {@literal <} 10<sup><i>n</i>+1</sup>; then let <i>a</i> 174 * be the mathematically exact quotient of <i>m</i> and 175 * 10<sup><i>n</i></sup> so that 1 ≤ <i>a</i> {@literal <} 10. 176 * The magnitude is then represented as the integer part of 177 * <i>a</i>, as a single decimal digit, followed by 178 * '{@code .}' ({@code '\u005Cu002E'}), followed by 179 * decimal digits representing the fractional part of 180 * <i>a</i>, followed by the letter '{@code E}' 181 * ({@code '\u005Cu0045'}), followed by a representation 182 * of <i>n</i> as a decimal integer, as produced by the 183 * method {@link java.lang.Integer#toString(int)}. 184 * 185 * </ul> 186 * </ul> 187 * How many digits must be printed for the fractional part of 188 * <i>m</i> or <i>a</i>? There must be at least one digit 189 * to represent the fractional part, and beyond that as many, but 190 * only as many, more digits as are needed to uniquely distinguish 191 * the argument value from adjacent values of type 192 * {@code float}. That is, suppose that <i>x</i> is the 193 * exact mathematical value represented by the decimal 194 * representation produced by this method for a finite nonzero 195 * argument <i>f</i>. Then <i>f</i> must be the {@code float} 196 * value nearest to <i>x</i>; or, if two {@code float} values are 197 * equally close to <i>x</i>, then <i>f</i> must be one of 198 * them and the least significant bit of the significand of 199 * <i>f</i> must be {@code 0}. 200 * 201 * <p>To create localized string representations of a floating-point 202 * value, use subclasses of {@link java.text.NumberFormat}. 203 * 204 * @param f the float to be converted. 205 * @return a string representation of the argument. 206 */ 207 public static String toString(float f) { 208 return FloatingDecimal.toJavaFormatString(f); 209 } 210 211 /** 212 * Returns a hexadecimal string representation of the 213 * {@code float} argument. All characters mentioned below are 214 * ASCII characters. 215 * 216 * <ul> 217 * <li>If the argument is NaN, the result is the string 218 * "{@code NaN}". 219 * <li>Otherwise, the result is a string that represents the sign and 220 * magnitude (absolute value) of the argument. If the sign is negative, 221 * the first character of the result is '{@code -}' 222 * ({@code '\u005Cu002D'}); if the sign is positive, no sign character 223 * appears in the result. As for the magnitude <i>m</i>: 224 * 225 * <ul> 226 * <li>If <i>m</i> is infinity, it is represented by the string 227 * {@code "Infinity"}; thus, positive infinity produces the 228 * result {@code "Infinity"} and negative infinity produces 229 * the result {@code "-Infinity"}. 230 * 231 * <li>If <i>m</i> is zero, it is represented by the string 232 * {@code "0x0.0p0"}; thus, negative zero produces the result 233 * {@code "-0x0.0p0"} and positive zero produces the result 234 * {@code "0x0.0p0"}. 235 * 236 * <li>If <i>m</i> is a {@code float} value with a 237 * normalized representation, substrings are used to represent the 238 * significand and exponent fields. The significand is 239 * represented by the characters {@code "0x1."} 240 * followed by a lowercase hexadecimal representation of the rest 241 * of the significand as a fraction. Trailing zeros in the 242 * hexadecimal representation are removed unless all the digits 243 * are zero, in which case a single zero is used. Next, the 244 * exponent is represented by {@code "p"} followed 245 * by a decimal string of the unbiased exponent as if produced by 246 * a call to {@link Integer#toString(int) Integer.toString} on the 247 * exponent value. 248 * 249 * <li>If <i>m</i> is a {@code float} value with a subnormal 250 * representation, the significand is represented by the 251 * characters {@code "0x0."} followed by a 252 * hexadecimal representation of the rest of the significand as a 253 * fraction. Trailing zeros in the hexadecimal representation are 254 * removed. Next, the exponent is represented by 255 * {@code "p-126"}. Note that there must be at 256 * least one nonzero digit in a subnormal significand. 257 * 258 * </ul> 259 * 260 * </ul> 261 * 262 * <table border> 263 * <caption>Examples</caption> 264 * <tr><th>Floating-point Value</th><th>Hexadecimal String</th> 265 * <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td> 266 * <tr><td>{@code -1.0}</td> <td>{@code -0x1.0p0}</td> 267 * <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td> 268 * <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td> 269 * <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td> 270 * <tr><td>{@code 0.25}</td> <td>{@code 0x1.0p-2}</td> 271 * <tr><td>{@code Float.MAX_VALUE}</td> 272 * <td>{@code 0x1.fffffep127}</td> 273 * <tr><td>{@code Minimum Normal Value}</td> 274 * <td>{@code 0x1.0p-126}</td> 275 * <tr><td>{@code Maximum Subnormal Value}</td> 276 * <td>{@code 0x0.fffffep-126}</td> 277 * <tr><td>{@code Float.MIN_VALUE}</td> 278 * <td>{@code 0x0.000002p-126}</td> 279 * </table> 280 * @param f the {@code float} to be converted. 281 * @return a hex string representation of the argument. 282 * @since 1.5 283 * @author Joseph D. Darcy 284 */ 285 public static String toHexString(float f) { 286 if (Math.abs(f) < Float.MIN_NORMAL 287 && f != 0.0f ) {// float subnormal 288 // Adjust exponent to create subnormal double, then 289 // replace subnormal double exponent with subnormal float 290 // exponent 291 String s = Double.toHexString(Math.scalb((double)f, 292 /* -1022+126 */ 293 Double.MIN_EXPONENT- 294 Float.MIN_EXPONENT)); 295 return s.replaceFirst("p-1022$", "p-126"); 296 } 297 else // double string will be the same as float string 298 return Double.toHexString(f); 299 } 300 301 /** 302 * Returns a {@code Float} object holding the 303 * {@code float} value represented by the argument string 304 * {@code s}. 305 * 306 * <p>If {@code s} is {@code null}, then a 307 * {@code NullPointerException} is thrown. 308 * 309 * <p>Leading and trailing whitespace characters in {@code s} 310 * are ignored. Whitespace is removed as if by the {@link 311 * String#trim} method; that is, both ASCII space and control 312 * characters are removed. The rest of {@code s} should 313 * constitute a <i>FloatValue</i> as described by the lexical 314 * syntax rules: 315 * 316 * <blockquote> 317 * <dl> 318 * <dt><i>FloatValue:</i> 319 * <dd><i>Sign<sub>opt</sub></i> {@code NaN} 320 * <dd><i>Sign<sub>opt</sub></i> {@code Infinity} 321 * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i> 322 * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i> 323 * <dd><i>SignedInteger</i> 324 * </dl> 325 * 326 * <dl> 327 * <dt><i>HexFloatingPointLiteral</i>: 328 * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i> 329 * </dl> 330 * 331 * <dl> 332 * <dt><i>HexSignificand:</i> 333 * <dd><i>HexNumeral</i> 334 * <dd><i>HexNumeral</i> {@code .} 335 * <dd>{@code 0x} <i>HexDigits<sub>opt</sub> 336 * </i>{@code .}<i> HexDigits</i> 337 * <dd>{@code 0X}<i> HexDigits<sub>opt</sub> 338 * </i>{@code .} <i>HexDigits</i> 339 * </dl> 340 * 341 * <dl> 342 * <dt><i>BinaryExponent:</i> 343 * <dd><i>BinaryExponentIndicator SignedInteger</i> 344 * </dl> 345 * 346 * <dl> 347 * <dt><i>BinaryExponentIndicator:</i> 348 * <dd>{@code p} 349 * <dd>{@code P} 350 * </dl> 351 * 352 * </blockquote> 353 * 354 * where <i>Sign</i>, <i>FloatingPointLiteral</i>, 355 * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and 356 * <i>FloatTypeSuffix</i> are as defined in the lexical structure 357 * sections of 358 * <cite>The Java™ Language Specification</cite>, 359 * except that underscores are not accepted between digits. 360 * If {@code s} does not have the form of 361 * a <i>FloatValue</i>, then a {@code NumberFormatException} 362 * is thrown. Otherwise, {@code s} is regarded as 363 * representing an exact decimal value in the usual 364 * "computerized scientific notation" or as an exact 365 * hexadecimal value; this exact numerical value is then 366 * conceptually converted to an "infinitely precise" 367 * binary value that is then rounded to type {@code float} 368 * by the usual round-to-nearest rule of IEEE 754 floating-point 369 * arithmetic, which includes preserving the sign of a zero 370 * value. 371 * 372 * Note that the round-to-nearest rule also implies overflow and 373 * underflow behaviour; if the exact value of {@code s} is large 374 * enough in magnitude (greater than or equal to ({@link 375 * #MAX_VALUE} + {@link Math#ulp(float) ulp(MAX_VALUE)}/2), 376 * rounding to {@code float} will result in an infinity and if the 377 * exact value of {@code s} is small enough in magnitude (less 378 * than or equal to {@link #MIN_VALUE}/2), rounding to float will 379 * result in a zero. 380 * 381 * Finally, after rounding a {@code Float} object representing 382 * this {@code float} value is returned. 383 * 384 * <p>To interpret localized string representations of a 385 * floating-point value, use subclasses of {@link 386 * java.text.NumberFormat}. 387 * 388 * <p>Note that trailing format specifiers, specifiers that 389 * determine the type of a floating-point literal 390 * ({@code 1.0f} is a {@code float} value; 391 * {@code 1.0d} is a {@code double} value), do 392 * <em>not</em> influence the results of this method. In other 393 * words, the numerical value of the input string is converted 394 * directly to the target floating-point type. In general, the 395 * two-step sequence of conversions, string to {@code double} 396 * followed by {@code double} to {@code float}, is 397 * <em>not</em> equivalent to converting a string directly to 398 * {@code float}. For example, if first converted to an 399 * intermediate {@code double} and then to 400 * {@code float}, the string<br> 401 * {@code "1.00000017881393421514957253748434595763683319091796875001d"}<br> 402 * results in the {@code float} value 403 * {@code 1.0000002f}; if the string is converted directly to 404 * {@code float}, <code>1.000000<b>1</b>f</code> results. 405 * 406 * <p>To avoid calling this method on an invalid string and having 407 * a {@code NumberFormatException} be thrown, the documentation 408 * for {@link Double#valueOf Double.valueOf} lists a regular 409 * expression which can be used to screen the input. 410 * 411 * @param s the string to be parsed. 412 * @return a {@code Float} object holding the value 413 * represented by the {@code String} argument. 414 * @throws NumberFormatException if the string does not contain a 415 * parsable number. 416 */ 417 public static Float valueOf(String s) throws NumberFormatException { 418 return new Float(parseFloat(s)); 419 } 420 421 /** 422 * Returns a {@code Float} instance representing the specified 423 * {@code float} value. 424 * If a new {@code Float} instance is not required, this method 425 * should generally be used in preference to the constructor 426 * {@link #Float(float)}, as this method is likely to yield 427 * significantly better space and time performance by caching 428 * frequently requested values. 429 * 430 * @param f a float value. 431 * @return a {@code Float} instance representing {@code f}. 432 * @since 1.5 433 */ 434 @HotSpotIntrinsicCandidate 435 public static Float valueOf(float f) { 436 return new Float(f); 437 } 438 439 /** 440 * Returns a new {@code float} initialized to the value 441 * represented by the specified {@code String}, as performed 442 * by the {@code valueOf} method of class {@code Float}. 443 * 444 * @param s the string to be parsed. 445 * @return the {@code float} value represented by the string 446 * argument. 447 * @throws NullPointerException if the string is null 448 * @throws NumberFormatException if the string does not contain a 449 * parsable {@code float}. 450 * @see java.lang.Float#valueOf(String) 451 * @since 1.2 452 */ 453 public static float parseFloat(String s) throws NumberFormatException { 454 return FloatingDecimal.parseFloat(s); 455 } 456 457 /** 458 * Returns {@code true} if the specified number is a 459 * Not-a-Number (NaN) value, {@code false} otherwise. 460 * 461 * @param v the value to be tested. 462 * @return {@code true} if the argument is NaN; 463 * {@code false} otherwise. 464 */ 465 public static boolean isNaN(float v) { 466 return (v != v); 467 } 468 469 /** 470 * Returns {@code true} if the specified number is infinitely 471 * large in magnitude, {@code false} otherwise. 472 * 473 * @param v the value to be tested. 474 * @return {@code true} if the argument is positive infinity or 475 * negative infinity; {@code false} otherwise. 476 */ 477 public static boolean isInfinite(float v) { 478 return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY); 479 } 480 481 482 /** 483 * Returns {@code true} if the argument is a finite floating-point 484 * value; returns {@code false} otherwise (for NaN and infinity 485 * arguments). 486 * 487 * @param f the {@code float} value to be tested 488 * @return {@code true} if the argument is a finite 489 * floating-point value, {@code false} otherwise. 490 * @since 1.8 491 */ 492 public static boolean isFinite(float f) { 493 return Math.abs(f) <= Float.MAX_VALUE; 494 } 495 496 /** 497 * The value of the Float. 498 * 499 * @serial 500 */ 501 private final float value; 502 503 /** 504 * Constructs a newly allocated {@code Float} object that 505 * represents the primitive {@code float} argument. 506 * 507 * @param value the value to be represented by the {@code Float}. 508 * 509 * @deprecated 510 * It is rarely appropriate to use this constructor. The static factory 511 * {@link #valueOf(float)} is generally a better choice, as it is 512 * likely to yield significantly better space and time performance. 513 */ 514 @Deprecated(since="9") 515 public Float(float value) { 516 this.value = value; 517 } 518 519 /** 520 * Constructs a newly allocated {@code Float} object that 521 * represents the argument converted to type {@code float}. 522 * 523 * @param value the value to be represented by the {@code Float}. 524 * 525 * @deprecated 526 * It is rarely appropriate to use this constructor. Instead, use the 527 * static factory method {@link #valueOf(float)} method as follows: 528 * {@code Float.valueOf((float)value)}. 529 */ 530 @Deprecated(since="9") 531 public Float(double value) { 532 this.value = (float)value; 533 } 534 535 /** 536 * Constructs a newly allocated {@code Float} object that 537 * represents the floating-point value of type {@code float} 538 * represented by the string. The string is converted to a 539 * {@code float} value as if by the {@code valueOf} method. 540 * 541 * @param s a string to be converted to a {@code Float}. 542 * @throws NumberFormatException if the string does not contain a 543 * parsable number. 544 * 545 * @deprecated 546 * It is rarely appropriate to use this constructor. 547 * Use {@link #parseFloat(String)} to convert a string to a 548 * {@code float} primitive, or use {@link #valueOf(String)} 549 * to convert a string to a {@code Float} object. 550 */ 551 @Deprecated(since="9") 552 public Float(String s) throws NumberFormatException { 553 value = parseFloat(s); 554 } 555 556 /** 557 * Returns {@code true} if this {@code Float} value is a 558 * Not-a-Number (NaN), {@code false} otherwise. 559 * 560 * @return {@code true} if the value represented by this object is 561 * NaN; {@code false} otherwise. 562 */ 563 public boolean isNaN() { 564 return isNaN(value); 565 } 566 567 /** 568 * Returns {@code true} if this {@code Float} value is 569 * infinitely large in magnitude, {@code false} otherwise. 570 * 571 * @return {@code true} if the value represented by this object is 572 * positive infinity or negative infinity; 573 * {@code false} otherwise. 574 */ 575 public boolean isInfinite() { 576 return isInfinite(value); 577 } 578 579 /** 580 * Returns a string representation of this {@code Float} object. 581 * The primitive {@code float} value represented by this object 582 * is converted to a {@code String} exactly as if by the method 583 * {@code toString} of one argument. 584 * 585 * @return a {@code String} representation of this object. 586 * @see java.lang.Float#toString(float) 587 */ 588 public String toString() { 589 return Float.toString(value); 590 } 591 592 /** 593 * Returns the value of this {@code Float} as a {@code byte} after 594 * a narrowing primitive conversion. 595 * 596 * @return the {@code float} value represented by this object 597 * converted to type {@code byte} 598 * @jls 5.1.3 Narrowing Primitive Conversions 599 */ 600 public byte byteValue() { 601 return (byte)value; 602 } 603 604 /** 605 * Returns the value of this {@code Float} as a {@code short} 606 * after a narrowing primitive conversion. 607 * 608 * @return the {@code float} value represented by this object 609 * converted to type {@code short} 610 * @jls 5.1.3 Narrowing Primitive Conversions 611 * @since 1.1 612 */ 613 public short shortValue() { 614 return (short)value; 615 } 616 617 /** 618 * Returns the value of this {@code Float} as an {@code int} after 619 * a narrowing primitive conversion. 620 * 621 * @return the {@code float} value represented by this object 622 * converted to type {@code int} 623 * @jls 5.1.3 Narrowing Primitive Conversions 624 */ 625 public int intValue() { 626 return (int)value; 627 } 628 629 /** 630 * Returns value of this {@code Float} as a {@code long} after a 631 * narrowing primitive conversion. 632 * 633 * @return the {@code float} value represented by this object 634 * converted to type {@code long} 635 * @jls 5.1.3 Narrowing Primitive Conversions 636 */ 637 public long longValue() { 638 return (long)value; 639 } 640 641 /** 642 * Returns the {@code float} value of this {@code Float} object. 643 * 644 * @return the {@code float} value represented by this object 645 */ 646 @HotSpotIntrinsicCandidate 647 public float floatValue() { 648 return value; 649 } 650 651 /** 652 * Returns the value of this {@code Float} as a {@code double} 653 * after a widening primitive conversion. 654 * 655 * @return the {@code float} value represented by this 656 * object converted to type {@code double} 657 * @jls 5.1.2 Widening Primitive Conversions 658 */ 659 public double doubleValue() { 660 return (double)value; 661 } 662 663 /** 664 * Returns a hash code for this {@code Float} object. The 665 * result is the integer bit representation, exactly as produced 666 * by the method {@link #floatToIntBits(float)}, of the primitive 667 * {@code float} value represented by this {@code Float} 668 * object. 669 * 670 * @return a hash code value for this object. 671 */ 672 @Override 673 public int hashCode() { 674 return Float.hashCode(value); 675 } 676 677 /** 678 * Returns a hash code for a {@code float} value; compatible with 679 * {@code Float.hashCode()}. 680 * 681 * @param value the value to hash 682 * @return a hash code value for a {@code float} value. 683 * @since 1.8 684 */ 685 public static int hashCode(float value) { 686 return floatToIntBits(value); 687 } 688 689 /** 690 691 * Compares this object against the specified object. The result 692 * is {@code true} if and only if the argument is not 693 * {@code null} and is a {@code Float} object that 694 * represents a {@code float} with the same value as the 695 * {@code float} represented by this object. For this 696 * purpose, two {@code float} values are considered to be the 697 * same if and only if the method {@link #floatToIntBits(float)} 698 * returns the identical {@code int} value when applied to 699 * each. 700 * 701 * <p>Note that in most cases, for two instances of class 702 * {@code Float}, {@code f1} and {@code f2}, the value 703 * of {@code f1.equals(f2)} is {@code true} if and only if 704 * 705 * <blockquote><pre> 706 * f1.floatValue() == f2.floatValue() 707 * </pre></blockquote> 708 * 709 * <p>also has the value {@code true}. However, there are two exceptions: 710 * <ul> 711 * <li>If {@code f1} and {@code f2} both represent 712 * {@code Float.NaN}, then the {@code equals} method returns 713 * {@code true}, even though {@code Float.NaN==Float.NaN} 714 * has the value {@code false}. 715 * <li>If {@code f1} represents {@code +0.0f} while 716 * {@code f2} represents {@code -0.0f}, or vice 717 * versa, the {@code equal} test has the value 718 * {@code false}, even though {@code 0.0f==-0.0f} 719 * has the value {@code true}. 720 * </ul> 721 * 722 * This definition allows hash tables to operate properly. 723 * 724 * @param obj the object to be compared 725 * @return {@code true} if the objects are the same; 726 * {@code false} otherwise. 727 * @see java.lang.Float#floatToIntBits(float) 728 */ 729 public boolean equals(Object obj) { 730 return (obj instanceof Float) 731 && (floatToIntBits(((Float)obj).value) == floatToIntBits(value)); 732 } 733 734 /** 735 * Returns a representation of the specified floating-point value 736 * according to the IEEE 754 floating-point "single format" bit 737 * layout. 738 * 739 * <p>Bit 31 (the bit that is selected by the mask 740 * {@code 0x80000000}) represents the sign of the floating-point 741 * number. 742 * Bits 30-23 (the bits that are selected by the mask 743 * {@code 0x7f800000}) represent the exponent. 744 * Bits 22-0 (the bits that are selected by the mask 745 * {@code 0x007fffff}) represent the significand (sometimes called 746 * the mantissa) of the floating-point number. 747 * 748 * <p>If the argument is positive infinity, the result is 749 * {@code 0x7f800000}. 750 * 751 * <p>If the argument is negative infinity, the result is 752 * {@code 0xff800000}. 753 * 754 * <p>If the argument is NaN, the result is {@code 0x7fc00000}. 755 * 756 * <p>In all cases, the result is an integer that, when given to the 757 * {@link #intBitsToFloat(int)} method, will produce a floating-point 758 * value the same as the argument to {@code floatToIntBits} 759 * (except all NaN values are collapsed to a single 760 * "canonical" NaN value). 761 * 762 * @param value a floating-point number. 763 * @return the bits that represent the floating-point number. 764 */ 765 @HotSpotIntrinsicCandidate 766 public static int floatToIntBits(float value) { 767 if (!isNaN(value)) { 768 return floatToRawIntBits(value); 769 } 770 return 0x7fc00000; 771 } 772 773 /** 774 * Returns a representation of the specified floating-point value 775 * according to the IEEE 754 floating-point "single format" bit 776 * layout, preserving Not-a-Number (NaN) values. 777 * 778 * <p>Bit 31 (the bit that is selected by the mask 779 * {@code 0x80000000}) represents the sign of the floating-point 780 * number. 781 * Bits 30-23 (the bits that are selected by the mask 782 * {@code 0x7f800000}) represent the exponent. 783 * Bits 22-0 (the bits that are selected by the mask 784 * {@code 0x007fffff}) represent the significand (sometimes called 785 * the mantissa) of the floating-point number. 786 * 787 * <p>If the argument is positive infinity, the result is 788 * {@code 0x7f800000}. 789 * 790 * <p>If the argument is negative infinity, the result is 791 * {@code 0xff800000}. 792 * 793 * <p>If the argument is NaN, the result is the integer representing 794 * the actual NaN value. Unlike the {@code floatToIntBits} 795 * method, {@code floatToRawIntBits} does not collapse all the 796 * bit patterns encoding a NaN to a single "canonical" 797 * NaN value. 798 * 799 * <p>In all cases, the result is an integer that, when given to the 800 * {@link #intBitsToFloat(int)} method, will produce a 801 * floating-point value the same as the argument to 802 * {@code floatToRawIntBits}. 803 * 804 * @param value a floating-point number. 805 * @return the bits that represent the floating-point number. 806 * @since 1.3 807 */ 808 @HotSpotIntrinsicCandidate 809 public static native int floatToRawIntBits(float value); 810 811 /** 812 * Returns the {@code float} value corresponding to a given 813 * bit representation. 814 * The argument is considered to be a representation of a 815 * floating-point value according to the IEEE 754 floating-point 816 * "single format" bit layout. 817 * 818 * <p>If the argument is {@code 0x7f800000}, the result is positive 819 * infinity. 820 * 821 * <p>If the argument is {@code 0xff800000}, the result is negative 822 * infinity. 823 * 824 * <p>If the argument is any value in the range 825 * {@code 0x7f800001} through {@code 0x7fffffff} or in 826 * the range {@code 0xff800001} through 827 * {@code 0xffffffff}, the result is a NaN. No IEEE 754 828 * floating-point operation provided by Java can distinguish 829 * between two NaN values of the same type with different bit 830 * patterns. Distinct values of NaN are only distinguishable by 831 * use of the {@code Float.floatToRawIntBits} method. 832 * 833 * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three 834 * values that can be computed from the argument: 835 * 836 * <blockquote><pre>{@code 837 * int s = ((bits >> 31) == 0) ? 1 : -1; 838 * int e = ((bits >> 23) & 0xff); 839 * int m = (e == 0) ? 840 * (bits & 0x7fffff) << 1 : 841 * (bits & 0x7fffff) | 0x800000; 842 * }</pre></blockquote> 843 * 844 * Then the floating-point result equals the value of the mathematical 845 * expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-150</sup>. 846 * 847 * <p>Note that this method may not be able to return a 848 * {@code float} NaN with exactly same bit pattern as the 849 * {@code int} argument. IEEE 754 distinguishes between two 850 * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The 851 * differences between the two kinds of NaN are generally not 852 * visible in Java. Arithmetic operations on signaling NaNs turn 853 * them into quiet NaNs with a different, but often similar, bit 854 * pattern. However, on some processors merely copying a 855 * signaling NaN also performs that conversion. In particular, 856 * copying a signaling NaN to return it to the calling method may 857 * perform this conversion. So {@code intBitsToFloat} may 858 * not be able to return a {@code float} with a signaling NaN 859 * bit pattern. Consequently, for some {@code int} values, 860 * {@code floatToRawIntBits(intBitsToFloat(start))} may 861 * <i>not</i> equal {@code start}. Moreover, which 862 * particular bit patterns represent signaling NaNs is platform 863 * dependent; although all NaN bit patterns, quiet or signaling, 864 * must be in the NaN range identified above. 865 * 866 * @param bits an integer. 867 * @return the {@code float} floating-point value with the same bit 868 * pattern. 869 */ 870 @HotSpotIntrinsicCandidate 871 public static native float intBitsToFloat(int bits); 872 873 /** 874 * Compares two {@code Float} objects numerically. There are 875 * two ways in which comparisons performed by this method differ 876 * from those performed by the Java language numerical comparison 877 * operators ({@code <, <=, ==, >=, >}) when 878 * applied to primitive {@code float} values: 879 * 880 * <ul><li> 881 * {@code Float.NaN} is considered by this method to 882 * be equal to itself and greater than all other 883 * {@code float} values 884 * (including {@code Float.POSITIVE_INFINITY}). 885 * <li> 886 * {@code 0.0f} is considered by this method to be greater 887 * than {@code -0.0f}. 888 * </ul> 889 * 890 * This ensures that the <i>natural ordering</i> of {@code Float} 891 * objects imposed by this method is <i>consistent with equals</i>. 892 * 893 * @param anotherFloat the {@code Float} to be compared. 894 * @return the value {@code 0} if {@code anotherFloat} is 895 * numerically equal to this {@code Float}; a value 896 * less than {@code 0} if this {@code Float} 897 * is numerically less than {@code anotherFloat}; 898 * and a value greater than {@code 0} if this 899 * {@code Float} is numerically greater than 900 * {@code anotherFloat}. 901 * 902 * @since 1.2 903 * @see Comparable#compareTo(Object) 904 */ 905 public int compareTo(Float anotherFloat) { 906 return Float.compare(value, anotherFloat.value); 907 } 908 909 /** 910 * Compares the two specified {@code float} values. The sign 911 * of the integer value returned is the same as that of the 912 * integer that would be returned by the call: 913 * <pre> 914 * new Float(f1).compareTo(new Float(f2)) 915 * </pre> 916 * 917 * @param f1 the first {@code float} to compare. 918 * @param f2 the second {@code float} to compare. 919 * @return the value {@code 0} if {@code f1} is 920 * numerically equal to {@code f2}; a value less than 921 * {@code 0} if {@code f1} is numerically less than 922 * {@code f2}; and a value greater than {@code 0} 923 * if {@code f1} is numerically greater than 924 * {@code f2}. 925 * @since 1.4 926 */ 927 public static int compare(float f1, float f2) { 928 if (f1 < f2) 929 return -1; // Neither val is NaN, thisVal is smaller 930 if (f1 > f2) 931 return 1; // Neither val is NaN, thisVal is larger 932 933 // Cannot use floatToRawIntBits because of possibility of NaNs. 934 int thisBits = Float.floatToIntBits(f1); 935 int anotherBits = Float.floatToIntBits(f2); 936 937 return (thisBits == anotherBits ? 0 : // Values are equal 938 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN) 939 1)); // (0.0, -0.0) or (NaN, !NaN) 940 } 941 942 /** 943 * Adds two {@code float} values together as per the + operator. 944 * 945 * @param a the first operand 946 * @param b the second operand 947 * @return the sum of {@code a} and {@code b} 948 * @jls 4.2.4 Floating-Point Operations 949 * @see java.util.function.BinaryOperator 950 * @since 1.8 951 */ 952 public static float sum(float a, float b) { 953 return a + b; 954 } 955 956 /** 957 * Returns the greater of two {@code float} values 958 * as if by calling {@link Math#max(float, float) Math.max}. 959 * 960 * @param a the first operand 961 * @param b the second operand 962 * @return the greater of {@code a} and {@code b} 963 * @see java.util.function.BinaryOperator 964 * @since 1.8 965 */ 966 public static float max(float a, float b) { 967 return Math.max(a, b); 968 } 969 970 /** 971 * Returns the smaller of two {@code float} values 972 * as if by calling {@link Math#min(float, float) Math.min}. 973 * 974 * @param a the first operand 975 * @param b the second operand 976 * @return the smaller of {@code a} and {@code b} 977 * @see java.util.function.BinaryOperator 978 * @since 1.8 979 */ 980 public static float min(float a, float b) { 981 return Math.min(a, b); 982 } 983 984 985 @Override 986 public Float resolveConstant(MethodHandles.Lookup lookup) { 987 return this; 988 } 989 990 /** use serialVersionUID from JDK 1.0.2 for interoperability */ 991 private static final long serialVersionUID = -2671257302660747028L; 992 }