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






 979     }
 980 
 981     /** use serialVersionUID from JDK 1.0.2 for interoperability */
 982     private static final long serialVersionUID = -2671257302660747028L;
 983 }
--- EOF ---