1 /*
   2  * Copyright (c) 1994, 2013, 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 sun.misc.FloatingDecimal;
  29 import sun.misc.FloatConsts;
  30 import sun.misc.DoubleConsts;
  31 
  32 /**
  33  * The {@code Float} class wraps a value of primitive type
  34  * {@code float} in an object. An object of type
  35  * {@code Float} contains a single field whose type is
  36  * {@code float}.
  37  *
  38  * <p>In addition, this class provides several methods for converting a
  39  * {@code float} to a {@code String} and a
  40  * {@code String} to a {@code float}, as well as other
  41  * constants and methods useful when dealing with a
  42  * {@code float}.
  43  *
  44  * @author  Lee Boynton
  45  * @author  Arthur van Hoff
  46  * @author  Joseph D. Darcy
  47  * @since 1.0
  48  */
  49 public final class Float extends Number implements Comparable<Float> {
  50     /**
  51      * A constant holding the positive infinity of type
  52      * {@code float}. It is equal to the value returned by
  53      * {@code Float.intBitsToFloat(0x7f800000)}.
  54      */
  55     public static final float POSITIVE_INFINITY = 1.0f / 0.0f;
  56 
  57     /**
  58      * A constant holding the negative infinity of type
  59      * {@code float}. It is equal to the value returned by
  60      * {@code Float.intBitsToFloat(0xff800000)}.
  61      */
  62     public static final float NEGATIVE_INFINITY = -1.0f / 0.0f;
  63 
  64     /**
  65      * A constant holding a Not-a-Number (NaN) value of type
  66      * {@code float}.  It is equivalent to the value returned by
  67      * {@code Float.intBitsToFloat(0x7fc00000)}.
  68      */
  69     public static final float NaN = 0.0f / 0.0f;
  70 
  71     /**
  72      * A constant holding the largest positive finite value of type
  73      * {@code float}, (2-2<sup>-23</sup>)&middot;2<sup>127</sup>.
  74      * It is equal to the hexadecimal floating-point literal
  75      * {@code 0x1.fffffeP+127f} and also equal to
  76      * {@code Float.intBitsToFloat(0x7f7fffff)}.
  77      */
  78     public static final float MAX_VALUE = 0x1.fffffeP+127f; // 3.4028235e+38f
  79 
  80     /**
  81      * A constant holding the smallest positive normal value of type
  82      * {@code float}, 2<sup>-126</sup>.  It is equal to the
  83      * hexadecimal floating-point literal {@code 0x1.0p-126f} and also
  84      * equal to {@code Float.intBitsToFloat(0x00800000)}.
  85      *
  86      * @since 1.6
  87      */
  88     public static final float MIN_NORMAL = 0x1.0p-126f; // 1.17549435E-38f
  89 
  90     /**
  91      * A constant holding the smallest positive nonzero value of type
  92      * {@code float}, 2<sup>-149</sup>. It is equal to the
  93      * hexadecimal floating-point literal {@code 0x0.000002P-126f}
  94      * and also equal to {@code Float.intBitsToFloat(0x1)}.
  95      */
  96     public static final float MIN_VALUE = 0x0.000002P-126f; // 1.4e-45f
  97 
  98     /**
  99      * Maximum exponent a finite {@code float} variable may have.  It
 100      * is equal to the value returned by {@code
 101      * Math.getExponent(Float.MAX_VALUE)}.
 102      *
 103      * @since 1.6
 104      */
 105     public static final int MAX_EXPONENT = 127;
 106 
 107     /**
 108      * Minimum exponent a normalized {@code float} variable may have.
 109      * It is equal to the value returned by {@code
 110      * Math.getExponent(Float.MIN_NORMAL)}.
 111      *
 112      * @since 1.6
 113      */
 114     public static final int MIN_EXPONENT = -126;
 115 
 116     /**
 117      * The number of bits used to represent a {@code float} value.
 118      *
 119      * @since 1.5
 120      */
 121     public static final int SIZE = 32;
 122 
 123     /**
 124      * The number of bytes used to represent a {@code float} value.
 125      *
 126      * @since 1.8
 127      */
 128     public static final int BYTES = SIZE / Byte.SIZE;
 129 
 130     /**
 131      * The {@code Class} instance representing the primitive type
 132      * {@code float}.
 133      *
 134      * @since 1.1
 135      */
 136     @SuppressWarnings("unchecked")
 137     public static final Class<Float> TYPE = (Class<Float>) Class.getPrimitiveClass("float");
 138 
 139     /**
 140      * Returns a string representation of the {@code float}
 141      * argument. All characters mentioned below are ASCII characters.
 142      * <ul>
 143      * <li>If the argument is NaN, the result is the string
 144      * "{@code NaN}".
 145      * <li>Otherwise, the result is a string that represents the sign and
 146      *     magnitude (absolute value) of the argument. If the sign is
 147      *     negative, the first character of the result is
 148      *     '{@code -}' ({@code '\u005Cu002D'}); if the sign is
 149      *     positive, no sign character appears in the result. As for
 150      *     the magnitude <i>m</i>:
 151      * <ul>
 152      * <li>If <i>m</i> is infinity, it is represented by the characters
 153      *     {@code "Infinity"}; thus, positive infinity produces
 154      *     the result {@code "Infinity"} and negative infinity
 155      *     produces the result {@code "-Infinity"}.
 156      * <li>If <i>m</i> is zero, it is represented by the characters
 157      *     {@code "0.0"}; thus, negative zero produces the result
 158      *     {@code "-0.0"} and positive zero produces the result
 159      *     {@code "0.0"}.
 160      * <li> If <i>m</i> is greater than or equal to 10<sup>-3</sup> but
 161      *      less than 10<sup>7</sup>, then it is represented as the
 162      *      integer part of <i>m</i>, in decimal form with no leading
 163      *      zeroes, followed by '{@code .}'
 164      *      ({@code '\u005Cu002E'}), followed by one or more
 165      *      decimal digits representing the fractional part of
 166      *      <i>m</i>.
 167      * <li> If <i>m</i> is less than 10<sup>-3</sup> or greater than or
 168      *      equal to 10<sup>7</sup>, then it is represented in
 169      *      so-called "computerized scientific notation." Let <i>n</i>
 170      *      be the unique integer such that 10<sup><i>n</i> </sup>&le;
 171      *      <i>m</i> {@literal <} 10<sup><i>n</i>+1</sup>; then let <i>a</i>
 172      *      be the mathematically exact quotient of <i>m</i> and
 173      *      10<sup><i>n</i></sup> so that 1 &le; <i>a</i> {@literal <} 10.
 174      *      The magnitude is then represented as the integer part of
 175      *      <i>a</i>, as a single decimal digit, followed by
 176      *      '{@code .}' ({@code '\u005Cu002E'}), followed by
 177      *      decimal digits representing the fractional part of
 178      *      <i>a</i>, followed by the letter '{@code E}'
 179      *      ({@code '\u005Cu0045'}), followed by a representation
 180      *      of <i>n</i> as a decimal integer, as produced by the
 181      *      method {@link java.lang.Integer#toString(int)}.
 182      *
 183      * </ul>
 184      * </ul>
 185      * How many digits must be printed for the fractional part of
 186      * <i>m</i> or <i>a</i>? There must be at least one digit
 187      * to represent the fractional part, and beyond that as many, but
 188      * only as many, more digits as are needed to uniquely distinguish
 189      * the argument value from adjacent values of type
 190      * {@code float}. That is, suppose that <i>x</i> is the
 191      * exact mathematical value represented by the decimal
 192      * representation produced by this method for a finite nonzero
 193      * argument <i>f</i>. Then <i>f</i> must be the {@code float}
 194      * value nearest to <i>x</i>; or, if two {@code float} values are
 195      * equally close to <i>x</i>, then <i>f</i> must be one of
 196      * them and the least significant bit of the significand of
 197      * <i>f</i> must be {@code 0}.
 198      *
 199      * <p>To create localized string representations of a floating-point
 200      * value, use subclasses of {@link java.text.NumberFormat}.
 201      *
 202      * @param   f   the float to be converted.
 203      * @return a string representation of the argument.
 204      */
 205     public static String toString(float f) {
 206         return FloatingDecimal.toJavaFormatString(f);
 207     }
 208 
 209     /**
 210      * Returns a hexadecimal string representation of the
 211      * {@code float} argument. All characters mentioned below are
 212      * ASCII characters.
 213      *
 214      * <ul>
 215      * <li>If the argument is NaN, the result is the string
 216      *     "{@code NaN}".
 217      * <li>Otherwise, the result is a string that represents the sign and
 218      * magnitude (absolute value) of the argument. If the sign is negative,
 219      * the first character of the result is '{@code -}'
 220      * ({@code '\u005Cu002D'}); if the sign is positive, no sign character
 221      * appears in the result. As for the magnitude <i>m</i>:
 222      *
 223      * <ul>
 224      * <li>If <i>m</i> is infinity, it is represented by the string
 225      * {@code "Infinity"}; thus, positive infinity produces the
 226      * result {@code "Infinity"} and negative infinity produces
 227      * the result {@code "-Infinity"}.
 228      *
 229      * <li>If <i>m</i> is zero, it is represented by the string
 230      * {@code "0x0.0p0"}; thus, negative zero produces the result
 231      * {@code "-0x0.0p0"} and positive zero produces the result
 232      * {@code "0x0.0p0"}.
 233      *
 234      * <li>If <i>m</i> is a {@code float} value with a
 235      * normalized representation, substrings are used to represent the
 236      * significand and exponent fields.  The significand is
 237      * represented by the characters {@code "0x1."}
 238      * followed by a lowercase hexadecimal representation of the rest
 239      * of the significand as a fraction.  Trailing zeros in the
 240      * hexadecimal representation are removed unless all the digits
 241      * are zero, in which case a single zero is used. Next, the
 242      * exponent is represented by {@code "p"} followed
 243      * by a decimal string of the unbiased exponent as if produced by
 244      * a call to {@link Integer#toString(int) Integer.toString} on the
 245      * exponent value.
 246      *
 247      * <li>If <i>m</i> is a {@code float} value with a subnormal
 248      * representation, the significand is represented by the
 249      * characters {@code "0x0."} followed by a
 250      * hexadecimal representation of the rest of the significand as a
 251      * fraction.  Trailing zeros in the hexadecimal representation are
 252      * removed. Next, the exponent is represented by
 253      * {@code "p-126"}.  Note that there must be at
 254      * least one nonzero digit in a subnormal significand.
 255      *
 256      * </ul>
 257      *
 258      * </ul>
 259      *
 260      * <table border>
 261      * <caption>Examples</caption>
 262      * <tr><th>Floating-point Value</th><th>Hexadecimal String</th>
 263      * <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td>
 264      * <tr><td>{@code -1.0}</td>        <td>{@code -0x1.0p0}</td>
 265      * <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td>
 266      * <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td>
 267      * <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td>
 268      * <tr><td>{@code 0.25}</td>        <td>{@code 0x1.0p-2}</td>
 269      * <tr><td>{@code Float.MAX_VALUE}</td>
 270      *     <td>{@code 0x1.fffffep127}</td>
 271      * <tr><td>{@code Minimum Normal Value}</td>
 272      *     <td>{@code 0x1.0p-126}</td>
 273      * <tr><td>{@code Maximum Subnormal Value}</td>
 274      *     <td>{@code 0x0.fffffep-126}</td>
 275      * <tr><td>{@code Float.MIN_VALUE}</td>
 276      *     <td>{@code 0x0.000002p-126}</td>
 277      * </table>
 278      * @param   f   the {@code float} to be converted.
 279      * @return a hex string representation of the argument.
 280      * @since 1.5
 281      * @author Joseph D. Darcy
 282      */
 283     public static String toHexString(float f) {
 284         if (Math.abs(f) < FloatConsts.MIN_NORMAL
 285             &&  f != 0.0f ) {// float subnormal
 286             // Adjust exponent to create subnormal double, then
 287             // replace subnormal double exponent with subnormal float
 288             // exponent
 289             String s = Double.toHexString(Math.scalb((double)f,
 290                                                      /* -1022+126 */
 291                                                      DoubleConsts.MIN_EXPONENT-
 292                                                      FloatConsts.MIN_EXPONENT));
 293             return s.replaceFirst("p-1022$", "p-126");
 294         }
 295         else // double string will be the same as float string
 296             return Double.toHexString(f);
 297     }
 298 
 299     /**
 300      * Returns a {@code Float} object holding the
 301      * {@code float} value represented by the argument string
 302      * {@code s}.
 303      *
 304      * <p>If {@code s} is {@code null}, then a
 305      * {@code NullPointerException} is thrown.
 306      *
 307      * <p>Leading and trailing whitespace characters in {@code s}
 308      * are ignored.  Whitespace is removed as if by the {@link
 309      * String#trim} method; that is, both ASCII space and control
 310      * characters are removed. The rest of {@code s} should
 311      * constitute a <i>FloatValue</i> as described by the lexical
 312      * syntax rules:
 313      *
 314      * <blockquote>
 315      * <dl>
 316      * <dt><i>FloatValue:</i>
 317      * <dd><i>Sign<sub>opt</sub></i> {@code NaN}
 318      * <dd><i>Sign<sub>opt</sub></i> {@code Infinity}
 319      * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
 320      * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
 321      * <dd><i>SignedInteger</i>
 322      * </dl>
 323      *
 324      * <dl>
 325      * <dt><i>HexFloatingPointLiteral</i>:
 326      * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
 327      * </dl>
 328      *
 329      * <dl>
 330      * <dt><i>HexSignificand:</i>
 331      * <dd><i>HexNumeral</i>
 332      * <dd><i>HexNumeral</i> {@code .}
 333      * <dd>{@code 0x} <i>HexDigits<sub>opt</sub>
 334      *     </i>{@code .}<i> HexDigits</i>
 335      * <dd>{@code 0X}<i> HexDigits<sub>opt</sub>
 336      *     </i>{@code .} <i>HexDigits</i>
 337      * </dl>
 338      *
 339      * <dl>
 340      * <dt><i>BinaryExponent:</i>
 341      * <dd><i>BinaryExponentIndicator SignedInteger</i>
 342      * </dl>
 343      *
 344      * <dl>
 345      * <dt><i>BinaryExponentIndicator:</i>
 346      * <dd>{@code p}
 347      * <dd>{@code P}
 348      * </dl>
 349      *
 350      * </blockquote>
 351      *
 352      * where <i>Sign</i>, <i>FloatingPointLiteral</i>,
 353      * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
 354      * <i>FloatTypeSuffix</i> are as defined in the lexical structure
 355      * sections of
 356      * <cite>The Java&trade; Language Specification</cite>,
 357      * except that underscores are not accepted between digits.
 358      * If {@code s} does not have the form of
 359      * a <i>FloatValue</i>, then a {@code NumberFormatException}
 360      * is thrown. Otherwise, {@code s} is regarded as
 361      * representing an exact decimal value in the usual
 362      * "computerized scientific notation" or as an exact
 363      * hexadecimal value; this exact numerical value is then
 364      * conceptually converted to an "infinitely precise"
 365      * binary value that is then rounded to type {@code float}
 366      * by the usual round-to-nearest rule of IEEE 754 floating-point
 367      * arithmetic, which includes preserving the sign of a zero
 368      * value.
 369      *
 370      * Note that the round-to-nearest rule also implies overflow and
 371      * underflow behaviour; if the exact value of {@code s} is large
 372      * enough in magnitude (greater than or equal to ({@link
 373      * #MAX_VALUE} + {@link Math#ulp(float) ulp(MAX_VALUE)}/2),
 374      * rounding to {@code float} will result in an infinity and if the
 375      * exact value of {@code s} is small enough in magnitude (less
 376      * than or equal to {@link #MIN_VALUE}/2), rounding to float will
 377      * result in a zero.
 378      *
 379      * Finally, after rounding a {@code Float} object representing
 380      * this {@code float} value is returned.
 381      *
 382      * <p>To interpret localized string representations of a
 383      * floating-point value, use subclasses of {@link
 384      * java.text.NumberFormat}.
 385      *
 386      * <p>Note that trailing format specifiers, specifiers that
 387      * determine the type of a floating-point literal
 388      * ({@code 1.0f} is a {@code float} value;
 389      * {@code 1.0d} is a {@code double} value), do
 390      * <em>not</em> influence the results of this method.  In other
 391      * words, the numerical value of the input string is converted
 392      * directly to the target floating-point type.  In general, the
 393      * two-step sequence of conversions, string to {@code double}
 394      * followed by {@code double} to {@code float}, is
 395      * <em>not</em> equivalent to converting a string directly to
 396      * {@code float}.  For example, if first converted to an
 397      * intermediate {@code double} and then to
 398      * {@code float}, the string<br>
 399      * {@code "1.00000017881393421514957253748434595763683319091796875001d"}<br>
 400      * results in the {@code float} value
 401      * {@code 1.0000002f}; if the string is converted directly to
 402      * {@code float}, <code>1.000000<b>1</b>f</code> results.
 403      *
 404      * <p>To avoid calling this method on an invalid string and having
 405      * a {@code NumberFormatException} be thrown, the documentation
 406      * for {@link Double#valueOf Double.valueOf} lists a regular
 407      * expression which can be used to screen the input.
 408      *
 409      * @param   s   the string to be parsed.
 410      * @return  a {@code Float} object holding the value
 411      *          represented by the {@code String} argument.
 412      * @throws  NumberFormatException  if the string does not contain a
 413      *          parsable number.
 414      */
 415     public static Float valueOf(String s) throws NumberFormatException {
 416         return new Float(parseFloat(s));
 417     }
 418 
 419     /**
 420      * Returns a {@code Float} instance representing the specified
 421      * {@code float} value.
 422      * If a new {@code Float} instance is not required, this method
 423      * should generally be used in preference to the constructor
 424      * {@link #Float(float)}, as this method is likely to yield
 425      * significantly better space and time performance by caching
 426      * frequently requested values.
 427      *
 428      * @param  f a float value.
 429      * @return a {@code Float} instance representing {@code f}.
 430      * @since  1.5
 431      */
 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) <= FloatConsts.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     public Float(float value) {
 507         this.value = value;
 508     }
 509 
 510     /**
 511      * Constructs a newly allocated {@code Float} object that
 512      * represents the argument converted to type {@code float}.
 513      *
 514      * @param   value   the value to be represented by the {@code Float}.
 515      */
 516     public Float(double value) {
 517         this.value = (float)value;
 518     }
 519 
 520     /**
 521      * Constructs a newly allocated {@code Float} object that
 522      * represents the floating-point value of type {@code float}
 523      * represented by the string. The string is converted to a
 524      * {@code float} value as if by the {@code valueOf} method.
 525      *
 526      * @param      s   a string to be converted to a {@code Float}.
 527      * @throws  NumberFormatException  if the string does not contain a
 528      *               parsable number.
 529      * @see        java.lang.Float#valueOf(java.lang.String)
 530      */
 531     public Float(String s) throws NumberFormatException {
 532         value = parseFloat(s);
 533     }
 534 
 535     /**
 536      * Returns {@code true} if this {@code Float} value is a
 537      * Not-a-Number (NaN), {@code false} otherwise.
 538      *
 539      * @return  {@code true} if the value represented by this object is
 540      *          NaN; {@code false} otherwise.
 541      */
 542     public boolean isNaN() {
 543         return isNaN(value);
 544     }
 545 
 546     /**
 547      * Returns {@code true} if this {@code Float} value is
 548      * infinitely large in magnitude, {@code false} otherwise.
 549      *
 550      * @return  {@code true} if the value represented by this object is
 551      *          positive infinity or negative infinity;
 552      *          {@code false} otherwise.
 553      */
 554     public boolean isInfinite() {
 555         return isInfinite(value);
 556     }
 557 
 558     /**
 559      * Returns a string representation of this {@code Float} object.
 560      * The primitive {@code float} value represented by this object
 561      * is converted to a {@code String} exactly as if by the method
 562      * {@code toString} of one argument.
 563      *
 564      * @return  a {@code String} representation of this object.
 565      * @see java.lang.Float#toString(float)
 566      */
 567     public String toString() {
 568         return Float.toString(value);
 569     }
 570 
 571     /**
 572      * Returns the value of this {@code Float} as a {@code byte} after
 573      * a narrowing primitive conversion.
 574      *
 575      * @return  the {@code float} value represented by this object
 576      *          converted to type {@code byte}
 577      * @jls 5.1.3 Narrowing Primitive Conversions
 578      */
 579     public byte byteValue() {
 580         return (byte)value;
 581     }
 582 
 583     /**
 584      * Returns the value of this {@code Float} as a {@code short}
 585      * after a narrowing primitive conversion.
 586      *
 587      * @return  the {@code float} value represented by this object
 588      *          converted to type {@code short}
 589      * @jls 5.1.3 Narrowing Primitive Conversions
 590      * @since 1.1
 591      */
 592     public short shortValue() {
 593         return (short)value;
 594     }
 595 
 596     /**
 597      * Returns the value of this {@code Float} as an {@code int} after
 598      * a narrowing primitive conversion.
 599      *
 600      * @return  the {@code float} value represented by this object
 601      *          converted to type {@code int}
 602      * @jls 5.1.3 Narrowing Primitive Conversions
 603      */
 604     public int intValue() {
 605         return (int)value;
 606     }
 607 
 608     /**
 609      * Returns value of this {@code Float} as a {@code long} after a
 610      * narrowing primitive conversion.
 611      *
 612      * @return  the {@code float} value represented by this object
 613      *          converted to type {@code long}
 614      * @jls 5.1.3 Narrowing Primitive Conversions
 615      */
 616     public long longValue() {
 617         return (long)value;
 618     }
 619 
 620     /**
 621      * Returns the {@code float} value of this {@code Float} object.
 622      *
 623      * @return the {@code float} value represented by this object
 624      */
 625     public float floatValue() {
 626         return value;
 627     }
 628 
 629     /**
 630      * Returns the value of this {@code Float} as a {@code double}
 631      * after a widening primitive conversion.
 632      *
 633      * @return the {@code float} value represented by this
 634      *         object converted to type {@code double}
 635      * @jls 5.1.2 Widening Primitive Conversions
 636      */
 637     public double doubleValue() {
 638         return (double)value;
 639     }
 640 
 641     /**
 642      * Returns a hash code for this {@code Float} object. The
 643      * result is the integer bit representation, exactly as produced
 644      * by the method {@link #floatToIntBits(float)}, of the primitive
 645      * {@code float} value represented by this {@code Float}
 646      * object.
 647      *
 648      * @return a hash code value for this object.
 649      */
 650     @Override
 651     public int hashCode() {
 652         return Float.hashCode(value);
 653     }
 654 
 655     /**
 656      * Returns a hash code for a {@code float} value; compatible with
 657      * {@code Float.hashCode()}.
 658      *
 659      * @param value the value to hash
 660      * @return a hash code value for a {@code float} value.
 661      * @since 1.8
 662      */
 663     public static int hashCode(float value) {
 664         return floatToIntBits(value);
 665     }
 666 
 667     /**
 668 
 669      * Compares this object against the specified object.  The result
 670      * is {@code true} if and only if the argument is not
 671      * {@code null} and is a {@code Float} object that
 672      * represents a {@code float} with the same value as the
 673      * {@code float} represented by this object. For this
 674      * purpose, two {@code float} values are considered to be the
 675      * same if and only if the method {@link #floatToIntBits(float)}
 676      * returns the identical {@code int} value when applied to
 677      * each.
 678      *
 679      * <p>Note that in most cases, for two instances of class
 680      * {@code Float}, {@code f1} and {@code f2}, the value
 681      * of {@code f1.equals(f2)} is {@code true} if and only if
 682      *
 683      * <blockquote><pre>
 684      *   f1.floatValue() == f2.floatValue()
 685      * </pre></blockquote>
 686      *
 687      * <p>also has the value {@code true}. However, there are two exceptions:
 688      * <ul>
 689      * <li>If {@code f1} and {@code f2} both represent
 690      *     {@code Float.NaN}, then the {@code equals} method returns
 691      *     {@code true}, even though {@code Float.NaN==Float.NaN}
 692      *     has the value {@code false}.
 693      * <li>If {@code f1} represents {@code +0.0f} while
 694      *     {@code f2} represents {@code -0.0f}, or vice
 695      *     versa, the {@code equal} test has the value
 696      *     {@code false}, even though {@code 0.0f==-0.0f}
 697      *     has the value {@code true}.
 698      * </ul>
 699      *
 700      * This definition allows hash tables to operate properly.
 701      *
 702      * @param obj the object to be compared
 703      * @return  {@code true} if the objects are the same;
 704      *          {@code false} otherwise.
 705      * @see java.lang.Float#floatToIntBits(float)
 706      */
 707     public boolean equals(Object obj) {
 708         return (obj instanceof Float)
 709                && (floatToIntBits(((Float)obj).value) == floatToIntBits(value));
 710     }
 711 
 712     /**
 713      * Returns a representation of the specified floating-point value
 714      * according to the IEEE 754 floating-point "single format" bit
 715      * layout.
 716      *
 717      * <p>Bit 31 (the bit that is selected by the mask
 718      * {@code 0x80000000}) represents the sign of the floating-point
 719      * number.
 720      * Bits 30-23 (the bits that are selected by the mask
 721      * {@code 0x7f800000}) represent the exponent.
 722      * Bits 22-0 (the bits that are selected by the mask
 723      * {@code 0x007fffff}) represent the significand (sometimes called
 724      * the mantissa) of the floating-point number.
 725      *
 726      * <p>If the argument is positive infinity, the result is
 727      * {@code 0x7f800000}.
 728      *
 729      * <p>If the argument is negative infinity, the result is
 730      * {@code 0xff800000}.
 731      *
 732      * <p>If the argument is NaN, the result is {@code 0x7fc00000}.
 733      *
 734      * <p>In all cases, the result is an integer that, when given to the
 735      * {@link #intBitsToFloat(int)} method, will produce a floating-point
 736      * value the same as the argument to {@code floatToIntBits}
 737      * (except all NaN values are collapsed to a single
 738      * "canonical" NaN value).
 739      *
 740      * @param   value   a floating-point number.
 741      * @return the bits that represent the floating-point number.
 742      */
 743     public static int floatToIntBits(float value) {
 744         if (!isNaN(value)) {
 745             return floatToRawIntBits(value);
 746         }
 747         return 0x7fc00000;
 748     }
 749 
 750     /**
 751      * Returns a representation of the specified floating-point value
 752      * according to the IEEE 754 floating-point "single format" bit
 753      * layout, preserving Not-a-Number (NaN) values.
 754      *
 755      * <p>Bit 31 (the bit that is selected by the mask
 756      * {@code 0x80000000}) represents the sign of the floating-point
 757      * number.
 758      * Bits 30-23 (the bits that are selected by the mask
 759      * {@code 0x7f800000}) represent the exponent.
 760      * Bits 22-0 (the bits that are selected by the mask
 761      * {@code 0x007fffff}) represent the significand (sometimes called
 762      * the mantissa) of the floating-point number.
 763      *
 764      * <p>If the argument is positive infinity, the result is
 765      * {@code 0x7f800000}.
 766      *
 767      * <p>If the argument is negative infinity, the result is
 768      * {@code 0xff800000}.
 769      *
 770      * <p>If the argument is NaN, the result is the integer representing
 771      * the actual NaN value.  Unlike the {@code floatToIntBits}
 772      * method, {@code floatToRawIntBits} does not collapse all the
 773      * bit patterns encoding a NaN to a single "canonical"
 774      * NaN value.
 775      *
 776      * <p>In all cases, the result is an integer that, when given to the
 777      * {@link #intBitsToFloat(int)} method, will produce a
 778      * floating-point value the same as the argument to
 779      * {@code floatToRawIntBits}.
 780      *
 781      * @param   value   a floating-point number.
 782      * @return the bits that represent the floating-point number.
 783      * @since 1.3
 784      */
 785     public static native int floatToRawIntBits(float value);
 786 
 787     /**
 788      * Returns the {@code float} value corresponding to a given
 789      * bit representation.
 790      * The argument is considered to be a representation of a
 791      * floating-point value according to the IEEE 754 floating-point
 792      * "single format" bit layout.
 793      *
 794      * <p>If the argument is {@code 0x7f800000}, the result is positive
 795      * infinity.
 796      *
 797      * <p>If the argument is {@code 0xff800000}, the result is negative
 798      * infinity.
 799      *
 800      * <p>If the argument is any value in the range
 801      * {@code 0x7f800001} through {@code 0x7fffffff} or in
 802      * the range {@code 0xff800001} through
 803      * {@code 0xffffffff}, the result is a NaN.  No IEEE 754
 804      * floating-point operation provided by Java can distinguish
 805      * between two NaN values of the same type with different bit
 806      * patterns.  Distinct values of NaN are only distinguishable by
 807      * use of the {@code Float.floatToRawIntBits} method.
 808      *
 809      * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
 810      * values that can be computed from the argument:
 811      *
 812      * <blockquote><pre>{@code
 813      * int s = ((bits >> 31) == 0) ? 1 : -1;
 814      * int e = ((bits >> 23) & 0xff);
 815      * int m = (e == 0) ?
 816      *                 (bits & 0x7fffff) << 1 :
 817      *                 (bits & 0x7fffff) | 0x800000;
 818      * }</pre></blockquote>
 819      *
 820      * Then the floating-point result equals the value of the mathematical
 821      * expression <i>s</i>&middot;<i>m</i>&middot;2<sup><i>e</i>-150</sup>.
 822      *
 823      * <p>Note that this method may not be able to return a
 824      * {@code float} NaN with exactly same bit pattern as the
 825      * {@code int} argument.  IEEE 754 distinguishes between two
 826      * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>.  The
 827      * differences between the two kinds of NaN are generally not
 828      * visible in Java.  Arithmetic operations on signaling NaNs turn
 829      * them into quiet NaNs with a different, but often similar, bit
 830      * pattern.  However, on some processors merely copying a
 831      * signaling NaN also performs that conversion.  In particular,
 832      * copying a signaling NaN to return it to the calling method may
 833      * perform this conversion.  So {@code intBitsToFloat} may
 834      * not be able to return a {@code float} with a signaling NaN
 835      * bit pattern.  Consequently, for some {@code int} values,
 836      * {@code floatToRawIntBits(intBitsToFloat(start))} may
 837      * <i>not</i> equal {@code start}.  Moreover, which
 838      * particular bit patterns represent signaling NaNs is platform
 839      * dependent; although all NaN bit patterns, quiet or signaling,
 840      * must be in the NaN range identified above.
 841      *
 842      * @param   bits   an integer.
 843      * @return  the {@code float} floating-point value with the same bit
 844      *          pattern.
 845      */
 846     public static native float intBitsToFloat(int bits);
 847 
 848     /**
 849      * Compares two {@code Float} objects numerically.  There are
 850      * two ways in which comparisons performed by this method differ
 851      * from those performed by the Java language numerical comparison
 852      * operators ({@code <, <=, ==, >=, >}) when
 853      * applied to primitive {@code float} values:
 854      *
 855      * <ul><li>
 856      *          {@code Float.NaN} is considered by this method to
 857      *          be equal to itself and greater than all other
 858      *          {@code float} values
 859      *          (including {@code Float.POSITIVE_INFINITY}).
 860      * <li>
 861      *          {@code 0.0f} is considered by this method to be greater
 862      *          than {@code -0.0f}.
 863      * </ul>
 864      *
 865      * This ensures that the <i>natural ordering</i> of {@code Float}
 866      * objects imposed by this method is <i>consistent with equals</i>.
 867      *
 868      * @param   anotherFloat   the {@code Float} to be compared.
 869      * @return  the value {@code 0} if {@code anotherFloat} is
 870      *          numerically equal to this {@code Float}; a value
 871      *          less than {@code 0} if this {@code Float}
 872      *          is numerically less than {@code anotherFloat};
 873      *          and a value greater than {@code 0} if this
 874      *          {@code Float} is numerically greater than
 875      *          {@code anotherFloat}.
 876      *
 877      * @since   1.2
 878      * @see Comparable#compareTo(Object)
 879      */
 880     public int compareTo(Float anotherFloat) {
 881         return Float.compare(value, anotherFloat.value);
 882     }
 883 
 884     /**
 885      * Compares the two specified {@code float} values. The sign
 886      * of the integer value returned is the same as that of the
 887      * integer that would be returned by the call:
 888      * <pre>
 889      *    new Float(f1).compareTo(new Float(f2))
 890      * </pre>
 891      *
 892      * @param   f1        the first {@code float} to compare.
 893      * @param   f2        the second {@code float} to compare.
 894      * @return  the value {@code 0} if {@code f1} is
 895      *          numerically equal to {@code f2}; a value less than
 896      *          {@code 0} if {@code f1} is numerically less than
 897      *          {@code f2}; and a value greater than {@code 0}
 898      *          if {@code f1} is numerically greater than
 899      *          {@code f2}.
 900      * @since 1.4
 901      */
 902     public static int compare(float f1, float f2) {
 903         if (f1 < f2)
 904             return -1;           // Neither val is NaN, thisVal is smaller
 905         if (f1 > f2)
 906             return 1;            // Neither val is NaN, thisVal is larger
 907 
 908         // Cannot use floatToRawIntBits because of possibility of NaNs.
 909         int thisBits    = Float.floatToIntBits(f1);
 910         int anotherBits = Float.floatToIntBits(f2);
 911 
 912         return (thisBits == anotherBits ?  0 : // Values are equal
 913                 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
 914                  1));                          // (0.0, -0.0) or (NaN, !NaN)
 915     }
 916 
 917     /**
 918      * Adds two {@code float} values together as per the + operator.
 919      *
 920      * @param a the first operand
 921      * @param b the second operand
 922      * @return the sum of {@code a} and {@code b}
 923      * @jls 4.2.4 Floating-Point Operations
 924      * @see java.util.function.BinaryOperator
 925      * @since 1.8
 926      */
 927     public static float sum(float a, float b) {
 928         return a + b;
 929     }
 930 
 931     /**
 932      * Returns the greater of two {@code float} values
 933      * as if by calling {@link Math#max(float, float) Math.max}.
 934      *
 935      * @param a the first operand
 936      * @param b the second operand
 937      * @return the greater of {@code a} and {@code b}
 938      * @see java.util.function.BinaryOperator
 939      * @since 1.8
 940      */
 941     public static float max(float a, float b) {
 942         return Math.max(a, b);
 943     }
 944 
 945     /**
 946      * Returns the smaller of two {@code float} values
 947      * as if by calling {@link Math#min(float, float) Math.min}.
 948      *
 949      * @param a the first operand
 950      * @param b the second operand
 951      * @return the smaller of {@code a} and {@code b}
 952      * @see java.util.function.BinaryOperator
 953      * @since 1.8
 954      */
 955     public static float min(float a, float b) {
 956         return Math.min(a, b);
 957     }
 958 
 959     /** use serialVersionUID from JDK 1.0.2 for interoperability */
 960     private static final long serialVersionUID = -2671257302660747028L;
 961 }