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3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4    *
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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 JDK1.0
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 JDK1.1
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 JDK1.1
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         int result = floatToRawIntBits(value);
745         // Check for NaN based on values of bit fields, maximum
746         // exponent and nonzero significand.
747         if ( ((result & FloatConsts.EXP_BIT_MASK) ==
748               FloatConsts.EXP_BIT_MASK) &&
749              (result & FloatConsts.SIGNIF_BIT_MASK) != 0)
750             result = 0x7fc00000;
751         return result;
752     }
753 
754     /**
755      * Returns a representation of the specified floating-point value
756      * according to the IEEE 754 floating-point "single format" bit
757      * layout, preserving Not-a-Number (NaN) values.
758      *
759      * <p>Bit 31 (the bit that is selected by the mask
760      * {@code 0x80000000}) represents the sign of the floating-point
761      * number.
762      * Bits 30-23 (the bits that are selected by the mask
763      * {@code 0x7f800000}) represent the exponent.
764      * Bits 22-0 (the bits that are selected by the mask
765      * {@code 0x007fffff}) represent the significand (sometimes called
766      * the mantissa) of the floating-point number.
767      *
768      * <p>If the argument is positive infinity, the result is
769      * {@code 0x7f800000}.
770      *
771      * <p>If the argument is negative infinity, the result is
772      * {@code 0xff800000}.
773      *
774      * <p>If the argument is NaN, the result is the integer representing
775      * the actual NaN value.  Unlike the {@code floatToIntBits}
776      * method, {@code floatToRawIntBits} does not collapse all the
777      * bit patterns encoding a NaN to a single "canonical"
778      * NaN value.
779      *
780      * <p>In all cases, the result is an integer that, when given to the
781      * {@link #intBitsToFloat(int)} method, will produce a
782      * floating-point value the same as the argument to
783      * {@code floatToRawIntBits}.
784      *
785      * @param   value   a floating-point number.
786      * @return the bits that represent the floating-point number.
787      * @since 1.3
788      */
789     public static native int floatToRawIntBits(float value);
790 
791     /**
792      * Returns the {@code float} value corresponding to a given
793      * bit representation.
794      * The argument is considered to be a representation of a
795      * floating-point value according to the IEEE 754 floating-point
796      * "single format" bit layout.
797      *
798      * <p>If the argument is {@code 0x7f800000}, the result is positive
799      * infinity.
800      *
801      * <p>If the argument is {@code 0xff800000}, the result is negative
802      * infinity.
803      *
804      * <p>If the argument is any value in the range
805      * {@code 0x7f800001} through {@code 0x7fffffff} or in
806      * the range {@code 0xff800001} through
807      * {@code 0xffffffff}, the result is a NaN.  No IEEE 754
808      * floating-point operation provided by Java can distinguish
809      * between two NaN values of the same type with different bit
810      * patterns.  Distinct values of NaN are only distinguishable by
811      * use of the {@code Float.floatToRawIntBits} method.
812      *
813      * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
814      * values that can be computed from the argument:
815      *
816      * <blockquote><pre>{@code
817      * int s = ((bits >> 31) == 0) ? 1 : -1;
818      * int e = ((bits >> 23) & 0xff);
819      * int m = (e == 0) ?
820      *                 (bits & 0x7fffff) << 1 :
821      *                 (bits & 0x7fffff) | 0x800000;
822      * }</pre></blockquote>
823      *
824      * Then the floating-point result equals the value of the mathematical
825      * expression <i>s</i>&middot;<i>m</i>&middot;2<sup><i>e</i>-150</sup>.
826      *
827      * <p>Note that this method may not be able to return a
828      * {@code float} NaN with exactly same bit pattern as the
829      * {@code int} argument.  IEEE 754 distinguishes between two
830      * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>.  The
831      * differences between the two kinds of NaN are generally not
832      * visible in Java.  Arithmetic operations on signaling NaNs turn
833      * them into quiet NaNs with a different, but often similar, bit
834      * pattern.  However, on some processors merely copying a
835      * signaling NaN also performs that conversion.  In particular,
836      * copying a signaling NaN to return it to the calling method may
837      * perform this conversion.  So {@code intBitsToFloat} may
838      * not be able to return a {@code float} with a signaling NaN
839      * bit pattern.  Consequently, for some {@code int} values,
840      * {@code floatToRawIntBits(intBitsToFloat(start))} may
841      * <i>not</i> equal {@code start}.  Moreover, which
842      * particular bit patterns represent signaling NaNs is platform
843      * dependent; although all NaN bit patterns, quiet or signaling,
844      * must be in the NaN range identified above.
845      *
846      * @param   bits   an integer.
847      * @return  the {@code float} floating-point value with the same bit
848      *          pattern.
849      */
850     public static native float intBitsToFloat(int bits);
851 
852     /**
853      * Compares two {@code Float} objects numerically.  There are
854      * two ways in which comparisons performed by this method differ
855      * from those performed by the Java language numerical comparison
856      * operators ({@code <, <=, ==, >=, >}) when
857      * applied to primitive {@code float} values:
858      *
859      * <ul><li>
860      *          {@code Float.NaN} is considered by this method to
861      *          be equal to itself and greater than all other
862      *          {@code float} values
863      *          (including {@code Float.POSITIVE_INFINITY}).
864      * <li>
865      *          {@code 0.0f} is considered by this method to be greater
866      *          than {@code -0.0f}.
867      * </ul>
868      *
869      * This ensures that the <i>natural ordering</i> of {@code Float}
870      * objects imposed by this method is <i>consistent with equals</i>.
871      *
872      * @param   anotherFloat   the {@code Float} to be compared.
873      * @return  the value {@code 0} if {@code anotherFloat} is
874      *          numerically equal to this {@code Float}; a value
875      *          less than {@code 0} if this {@code Float}
876      *          is numerically less than {@code anotherFloat};
877      *          and a value greater than {@code 0} if this
878      *          {@code Float} is numerically greater than
879      *          {@code anotherFloat}.
880      *
881      * @since   1.2
882      * @see Comparable#compareTo(Object)
883      */
884     public int compareTo(Float anotherFloat) {
885         return Float.compare(value, anotherFloat.value);
886     }
887 
888     /**
889      * Compares the two specified {@code float} values. The sign
890      * of the integer value returned is the same as that of the
891      * integer that would be returned by the call:
892      * <pre>
893      *    new Float(f1).compareTo(new Float(f2))
894      * </pre>
895      *
896      * @param   f1        the first {@code float} to compare.
897      * @param   f2        the second {@code float} to compare.
898      * @return  the value {@code 0} if {@code f1} is
899      *          numerically equal to {@code f2}; a value less than
900      *          {@code 0} if {@code f1} is numerically less than
901      *          {@code f2}; and a value greater than {@code 0}
902      *          if {@code f1} is numerically greater than
903      *          {@code f2}.
904      * @since 1.4
905      */
906     public static int compare(float f1, float f2) {
907         if (f1 < f2)
908             return -1;           // Neither val is NaN, thisVal is smaller
909         if (f1 > f2)
910             return 1;            // Neither val is NaN, thisVal is larger
911 
912         // Cannot use floatToRawIntBits because of possibility of NaNs.
913         int thisBits    = Float.floatToIntBits(f1);
914         int anotherBits = Float.floatToIntBits(f2);
915 
916         return (thisBits == anotherBits ?  0 : // Values are equal
917                 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
918                  1));                          // (0.0, -0.0) or (NaN, !NaN)
919     }
920 
921     /**
922      * Adds two {@code float} values together as per the + operator.
923      *
924      * @param a the first operand
925      * @param b the second operand
926      * @return the sum of {@code a} and {@code b}
927      * @jls 4.2.4 Floating-Point Operations
928      * @see java.util.function.BinaryOperator
929      * @since 1.8
930      */
931     public static float sum(float a, float b) {
932         return a + b;
933     }
934 
935     /**
936      * Returns the greater of two {@code float} values
937      * as if by calling {@link Math#max(float, float) Math.max}.
938      *
939      * @param a the first operand
940      * @param b the second operand
941      * @return the greater of {@code a} and {@code b}
942      * @see java.util.function.BinaryOperator
943      * @since 1.8
944      */
945     public static float max(float a, float b) {
946         return Math.max(a, b);
947     }
948 
949     /**
950      * Returns the smaller of two {@code float} values
951      * as if by calling {@link Math#min(float, float) Math.min}.
952      *
953      * @param a the first operand
954      * @param b the second operand
955      * @return the smaller of {@code a} and {@code b}
956      * @see java.util.function.BinaryOperator
957      * @since 1.8
958      */
959     public static float min(float a, float b) {
960         return Math.min(a, b);
961     }
962 
963     /** use serialVersionUID from JDK 1.0.2 for interoperability */
964     private static final long serialVersionUID = -2671257302660747028L;
965 }