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
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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>)·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>≤
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 ≤ <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 class="plain">
260 * <caption>Examples</caption>
261 * <thead>
262 * <tr><th>Floating-point Value</th><th>Hexadecimal String</th>
263 * </thead>
264 * <tbody>
265 * <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td>
266 * <tr><td>{@code -1.0}</td> <td>{@code -0x1.0p0}</td>
267 * <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td>
268 * <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td>
269 * <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td>
270 * <tr><td>{@code 0.25}</td> <td>{@code 0x1.0p-2}</td>
271 * <tr><td>{@code Float.MAX_VALUE}</td>
272 * <td>{@code 0x1.fffffep127}</td>
273 * <tr><td>{@code Minimum Normal Value}</td>
274 * <td>{@code 0x1.0p-126}</td>
275 * <tr><td>{@code Maximum Subnormal Value}</td>
276 * <td>{@code 0x0.fffffep-126}</td>
277 * <tr><td>{@code Float.MIN_VALUE}</td>
278 * <td>{@code 0x0.000002p-126}</td>
279 * </tbody>
280 * </table>
281 * @param f the {@code float} to be converted.
282 * @return a hex string representation of the argument.
283 * @since 1.5
284 * @author Joseph D. Darcy
285 */
286 public static String toHexString(float f) {
287 if (Math.abs(f) < Float.MIN_NORMAL
288 && f != 0.0f ) {// float subnormal
289 // Adjust exponent to create subnormal double, then
290 // replace subnormal double exponent with subnormal float
291 // exponent
292 String s = Double.toHexString(Math.scalb((double)f,
293 /* -1022+126 */
294 Double.MIN_EXPONENT-
295 Float.MIN_EXPONENT));
296 return s.replaceFirst("p-1022$", "p-126");
297 }
298 else // double string will be the same as float string
299 return Double.toHexString(f);
300 }
301
302 /**
303 * Returns a {@code Float} object holding the
304 * {@code float} value represented by the argument string
305 * {@code s}.
306 *
307 * <p>If {@code s} is {@code null}, then a
308 * {@code NullPointerException} is thrown.
309 *
310 * <p>Leading and trailing whitespace characters in {@code s}
311 * are ignored. Whitespace is removed as if by the {@link
312 * String#trim} method; that is, both ASCII space and control
313 * characters are removed. The rest of {@code s} should
314 * constitute a <i>FloatValue</i> as described by the lexical
315 * syntax rules:
316 *
317 * <blockquote>
318 * <dl>
319 * <dt><i>FloatValue:</i>
320 * <dd><i>Sign<sub>opt</sub></i> {@code NaN}
321 * <dd><i>Sign<sub>opt</sub></i> {@code Infinity}
322 * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
323 * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
324 * <dd><i>SignedInteger</i>
325 * </dl>
326 *
327 * <dl>
328 * <dt><i>HexFloatingPointLiteral</i>:
329 * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
330 * </dl>
331 *
332 * <dl>
333 * <dt><i>HexSignificand:</i>
334 * <dd><i>HexNumeral</i>
335 * <dd><i>HexNumeral</i> {@code .}
336 * <dd>{@code 0x} <i>HexDigits<sub>opt</sub>
337 * </i>{@code .}<i> HexDigits</i>
338 * <dd>{@code 0X}<i> HexDigits<sub>opt</sub>
339 * </i>{@code .} <i>HexDigits</i>
340 * </dl>
341 *
342 * <dl>
343 * <dt><i>BinaryExponent:</i>
344 * <dd><i>BinaryExponentIndicator SignedInteger</i>
345 * </dl>
346 *
347 * <dl>
348 * <dt><i>BinaryExponentIndicator:</i>
349 * <dd>{@code p}
350 * <dd>{@code P}
351 * </dl>
352 *
353 * </blockquote>
354 *
355 * where <i>Sign</i>, <i>FloatingPointLiteral</i>,
356 * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
357 * <i>FloatTypeSuffix</i> are as defined in the lexical structure
358 * sections of
359 * <cite>The Java™ Language Specification</cite>,
360 * except that underscores are not accepted between digits.
361 * If {@code s} does not have the form of
362 * a <i>FloatValue</i>, then a {@code NumberFormatException}
363 * is thrown. Otherwise, {@code s} is regarded as
364 * representing an exact decimal value in the usual
365 * "computerized scientific notation" or as an exact
366 * hexadecimal value; this exact numerical value is then
367 * conceptually converted to an "infinitely precise"
368 * binary value that is then rounded to type {@code float}
369 * by the usual round-to-nearest rule of IEEE 754 floating-point
370 * arithmetic, which includes preserving the sign of a zero
371 * value.
372 *
373 * Note that the round-to-nearest rule also implies overflow and
374 * underflow behaviour; if the exact value of {@code s} is large
375 * enough in magnitude (greater than or equal to ({@link
376 * #MAX_VALUE} + {@link Math#ulp(float) ulp(MAX_VALUE)}/2),
377 * rounding to {@code float} will result in an infinity and if the
378 * exact value of {@code s} is small enough in magnitude (less
379 * than or equal to {@link #MIN_VALUE}/2), rounding to float will
380 * result in a zero.
381 *
382 * Finally, after rounding a {@code Float} object representing
383 * this {@code float} value is returned.
384 *
385 * <p>To interpret localized string representations of a
386 * floating-point value, use subclasses of {@link
387 * java.text.NumberFormat}.
388 *
389 * <p>Note that trailing format specifiers, specifiers that
390 * determine the type of a floating-point literal
391 * ({@code 1.0f} is a {@code float} value;
392 * {@code 1.0d} is a {@code double} value), do
393 * <em>not</em> influence the results of this method. In other
394 * words, the numerical value of the input string is converted
395 * directly to the target floating-point type. In general, the
396 * two-step sequence of conversions, string to {@code double}
397 * followed by {@code double} to {@code float}, is
398 * <em>not</em> equivalent to converting a string directly to
399 * {@code float}. For example, if first converted to an
400 * intermediate {@code double} and then to
401 * {@code float}, the string<br>
402 * {@code "1.00000017881393421514957253748434595763683319091796875001d"}<br>
403 * results in the {@code float} value
404 * {@code 1.0000002f}; if the string is converted directly to
405 * {@code float}, <code>1.000000<b>1</b>f</code> results.
406 *
407 * <p>To avoid calling this method on an invalid string and having
408 * a {@code NumberFormatException} be thrown, the documentation
409 * for {@link Double#valueOf Double.valueOf} lists a regular
410 * expression which can be used to screen the input.
411 *
412 * @param s the string to be parsed.
413 * @return a {@code Float} object holding the value
414 * represented by the {@code String} argument.
415 * @throws NumberFormatException if the string does not contain a
416 * parsable number.
417 */
418 public static Float valueOf(String s) throws NumberFormatException {
419 return new Float(parseFloat(s));
420 }
421
422 /**
423 * Returns a {@code Float} instance representing the specified
424 * {@code float} value.
425 * If a new {@code Float} instance is not required, this method
426 * should generally be used in preference to the constructor
427 * {@link #Float(float)}, as this method is likely to yield
428 * significantly better space and time performance by caching
429 * frequently requested values.
430 *
431 * @param f a float value.
432 * @return a {@code Float} instance representing {@code f}.
433 * @since 1.5
434 */
435 @HotSpotIntrinsicCandidate
436 public static Float valueOf(float f) {
437 return new Float(f);
438 }
439
440 /**
441 * Returns a new {@code float} initialized to the value
442 * represented by the specified {@code String}, as performed
443 * by the {@code valueOf} method of class {@code Float}.
444 *
445 * @param s the string to be parsed.
446 * @return the {@code float} value represented by the string
447 * argument.
448 * @throws NullPointerException if the string is null
449 * @throws NumberFormatException if the string does not contain a
450 * parsable {@code float}.
451 * @see java.lang.Float#valueOf(String)
452 * @since 1.2
453 */
454 public static float parseFloat(String s) throws NumberFormatException {
455 return FloatingDecimal.parseFloat(s);
456 }
457
458 /**
459 * Returns {@code true} if the specified number is a
460 * Not-a-Number (NaN) value, {@code false} otherwise.
461 *
462 * @param v the value to be tested.
463 * @return {@code true} if the argument is NaN;
464 * {@code false} otherwise.
465 */
466 public static boolean isNaN(float v) {
467 return (v != v);
468 }
469
470 /**
471 * Returns {@code true} if the specified number is infinitely
472 * large in magnitude, {@code false} otherwise.
473 *
474 * @param v the value to be tested.
475 * @return {@code true} if the argument is positive infinity or
476 * negative infinity; {@code false} otherwise.
477 */
478 public static boolean isInfinite(float v) {
479 return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
480 }
481
482
483 /**
484 * Returns {@code true} if the argument is a finite floating-point
485 * value; returns {@code false} otherwise (for NaN and infinity
486 * arguments).
487 *
488 * @param f the {@code float} value to be tested
489 * @return {@code true} if the argument is a finite
490 * floating-point value, {@code false} otherwise.
491 * @since 1.8
492 */
493 public static boolean isFinite(float f) {
494 return Math.abs(f) <= Float.MAX_VALUE;
495 }
496
497 /**
498 * The value of the Float.
499 *
500 * @serial
501 */
502 private final float value;
503
504 /**
505 * Constructs a newly allocated {@code Float} object that
506 * represents the primitive {@code float} argument.
507 *
508 * @param value the value to be represented by the {@code Float}.
509 *
510 * @deprecated
511 * It is rarely appropriate to use this constructor. The static factory
512 * {@link #valueOf(float)} is generally a better choice, as it is
513 * likely to yield significantly better space and time performance.
514 */
515 @Deprecated(since="9")
516 public Float(float value) {
517 this.value = value;
518 }
519
520 /**
521 * Constructs a newly allocated {@code Float} object that
522 * represents the argument converted to type {@code float}.
523 *
524 * @param value the value to be represented by the {@code Float}.
525 *
526 * @deprecated
527 * It is rarely appropriate to use this constructor. Instead, use the
528 * static factory method {@link #valueOf(float)} method as follows:
529 * {@code Float.valueOf((float)value)}.
530 */
531 @Deprecated(since="9")
532 public Float(double value) {
533 this.value = (float)value;
534 }
535
536 /**
537 * Constructs a newly allocated {@code Float} object that
538 * represents the floating-point value of type {@code float}
539 * represented by the string. The string is converted to a
540 * {@code float} value as if by the {@code valueOf} method.
541 *
542 * @param s a string to be converted to a {@code Float}.
543 * @throws NumberFormatException if the string does not contain a
544 * parsable number.
545 *
546 * @deprecated
547 * It is rarely appropriate to use this constructor.
548 * Use {@link #parseFloat(String)} to convert a string to a
549 * {@code float} primitive, or use {@link #valueOf(String)}
550 * to convert a string to a {@code Float} object.
551 */
552 @Deprecated(since="9")
553 public Float(String s) throws NumberFormatException {
554 value = parseFloat(s);
555 }
556
557 /**
558 * Returns {@code true} if this {@code Float} value is a
559 * Not-a-Number (NaN), {@code false} otherwise.
560 *
561 * @return {@code true} if the value represented by this object is
562 * NaN; {@code false} otherwise.
563 */
564 public boolean isNaN() {
565 return isNaN(value);
566 }
567
568 /**
569 * Returns {@code true} if this {@code Float} value is
570 * infinitely large in magnitude, {@code false} otherwise.
571 *
572 * @return {@code true} if the value represented by this object is
573 * positive infinity or negative infinity;
574 * {@code false} otherwise.
575 */
576 public boolean isInfinite() {
577 return isInfinite(value);
578 }
579
580 /**
581 * Returns a string representation of this {@code Float} object.
582 * The primitive {@code float} value represented by this object
583 * is converted to a {@code String} exactly as if by the method
584 * {@code toString} of one argument.
585 *
586 * @return a {@code String} representation of this object.
587 * @see java.lang.Float#toString(float)
588 */
589 public String toString() {
590 return Float.toString(value);
591 }
592
593 /**
594 * Returns the value of this {@code Float} as a {@code byte} after
595 * a narrowing primitive conversion.
596 *
597 * @return the {@code float} value represented by this object
598 * converted to type {@code byte}
599 * @jls 5.1.3 Narrowing Primitive Conversions
600 */
601 public byte byteValue() {
602 return (byte)value;
603 }
604
605 /**
606 * Returns the value of this {@code Float} as a {@code short}
607 * after a narrowing primitive conversion.
608 *
609 * @return the {@code float} value represented by this object
610 * converted to type {@code short}
611 * @jls 5.1.3 Narrowing Primitive Conversions
612 * @since 1.1
613 */
614 public short shortValue() {
615 return (short)value;
616 }
617
618 /**
619 * Returns the value of this {@code Float} as an {@code int} after
620 * a narrowing primitive conversion.
621 *
622 * @return the {@code float} value represented by this object
623 * converted to type {@code int}
624 * @jls 5.1.3 Narrowing Primitive Conversions
625 */
626 public int intValue() {
627 return (int)value;
628 }
629
630 /**
631 * Returns value of this {@code Float} as a {@code long} after a
632 * narrowing primitive conversion.
633 *
634 * @return the {@code float} value represented by this object
635 * converted to type {@code long}
636 * @jls 5.1.3 Narrowing Primitive Conversions
637 */
638 public long longValue() {
639 return (long)value;
640 }
641
642 /**
643 * Returns the {@code float} value of this {@code Float} object.
644 *
645 * @return the {@code float} value represented by this object
646 */
647 @HotSpotIntrinsicCandidate
648 public float floatValue() {
649 return value;
650 }
651
652 /**
653 * Returns the value of this {@code Float} as a {@code double}
654 * after a widening primitive conversion.
655 *
656 * @return the {@code float} value represented by this
657 * object converted to type {@code double}
658 * @jls 5.1.2 Widening Primitive Conversions
659 */
660 public double doubleValue() {
661 return (double)value;
662 }
663
664 /**
665 * Returns a hash code for this {@code Float} object. The
666 * result is the integer bit representation, exactly as produced
667 * by the method {@link #floatToIntBits(float)}, of the primitive
668 * {@code float} value represented by this {@code Float}
669 * object.
670 *
671 * @return a hash code value for this object.
672 */
673 @Override
674 public int hashCode() {
675 return Float.hashCode(value);
676 }
677
678 /**
679 * Returns a hash code for a {@code float} value; compatible with
680 * {@code Float.hashCode()}.
681 *
682 * @param value the value to hash
683 * @return a hash code value for a {@code float} value.
684 * @since 1.8
685 */
686 public static int hashCode(float value) {
687 return floatToIntBits(value);
688 }
689
690 /**
691
692 * Compares this object against the specified object. The result
693 * is {@code true} if and only if the argument is not
694 * {@code null} and is a {@code Float} object that
695 * represents a {@code float} with the same value as the
696 * {@code float} represented by this object. For this
697 * purpose, two {@code float} values are considered to be the
698 * same if and only if the method {@link #floatToIntBits(float)}
699 * returns the identical {@code int} value when applied to
700 * each.
701 *
702 * <p>Note that in most cases, for two instances of class
703 * {@code Float}, {@code f1} and {@code f2}, the value
704 * of {@code f1.equals(f2)} is {@code true} if and only if
705 *
706 * <blockquote><pre>
707 * f1.floatValue() == f2.floatValue()
708 * </pre></blockquote>
709 *
710 * <p>also has the value {@code true}. However, there are two exceptions:
711 * <ul>
712 * <li>If {@code f1} and {@code f2} both represent
713 * {@code Float.NaN}, then the {@code equals} method returns
714 * {@code true}, even though {@code Float.NaN==Float.NaN}
715 * has the value {@code false}.
716 * <li>If {@code f1} represents {@code +0.0f} while
717 * {@code f2} represents {@code -0.0f}, or vice
718 * versa, the {@code equal} test has the value
719 * {@code false}, even though {@code 0.0f==-0.0f}
720 * has the value {@code true}.
721 * </ul>
722 *
723 * This definition allows hash tables to operate properly.
724 *
725 * @param obj the object to be compared
726 * @return {@code true} if the objects are the same;
727 * {@code false} otherwise.
728 * @see java.lang.Float#floatToIntBits(float)
729 */
730 public boolean equals(Object obj) {
731 return (obj instanceof Float)
732 && (floatToIntBits(((Float)obj).value) == floatToIntBits(value));
733 }
734
735 /**
736 * Returns a representation of the specified floating-point value
737 * according to the IEEE 754 floating-point "single format" bit
738 * layout.
739 *
740 * <p>Bit 31 (the bit that is selected by the mask
741 * {@code 0x80000000}) represents the sign of the floating-point
742 * number.
743 * Bits 30-23 (the bits that are selected by the mask
744 * {@code 0x7f800000}) represent the exponent.
745 * Bits 22-0 (the bits that are selected by the mask
746 * {@code 0x007fffff}) represent the significand (sometimes called
747 * the mantissa) of the floating-point number.
748 *
749 * <p>If the argument is positive infinity, the result is
750 * {@code 0x7f800000}.
751 *
752 * <p>If the argument is negative infinity, the result is
753 * {@code 0xff800000}.
754 *
755 * <p>If the argument is NaN, the result is {@code 0x7fc00000}.
756 *
757 * <p>In all cases, the result is an integer that, when given to the
758 * {@link #intBitsToFloat(int)} method, will produce a floating-point
759 * value the same as the argument to {@code floatToIntBits}
760 * (except all NaN values are collapsed to a single
761 * "canonical" NaN value).
762 *
763 * @param value a floating-point number.
764 * @return the bits that represent the floating-point number.
765 */
766 @HotSpotIntrinsicCandidate
767 public static int floatToIntBits(float value) {
768 if (!isNaN(value)) {
769 return floatToRawIntBits(value);
770 }
771 return 0x7fc00000;
772 }
773
774 /**
775 * Returns a representation of the specified floating-point value
776 * according to the IEEE 754 floating-point "single format" bit
777 * layout, preserving Not-a-Number (NaN) values.
778 *
779 * <p>Bit 31 (the bit that is selected by the mask
780 * {@code 0x80000000}) represents the sign of the floating-point
781 * number.
782 * Bits 30-23 (the bits that are selected by the mask
783 * {@code 0x7f800000}) represent the exponent.
784 * Bits 22-0 (the bits that are selected by the mask
785 * {@code 0x007fffff}) represent the significand (sometimes called
786 * the mantissa) of the floating-point number.
787 *
788 * <p>If the argument is positive infinity, the result is
789 * {@code 0x7f800000}.
790 *
791 * <p>If the argument is negative infinity, the result is
792 * {@code 0xff800000}.
793 *
794 * <p>If the argument is NaN, the result is the integer representing
795 * the actual NaN value. Unlike the {@code floatToIntBits}
796 * method, {@code floatToRawIntBits} does not collapse all the
797 * bit patterns encoding a NaN to a single "canonical"
798 * NaN value.
799 *
800 * <p>In all cases, the result is an integer that, when given to the
801 * {@link #intBitsToFloat(int)} method, will produce a
802 * floating-point value the same as the argument to
803 * {@code floatToRawIntBits}.
804 *
805 * @param value a floating-point number.
806 * @return the bits that represent the floating-point number.
807 * @since 1.3
808 */
809 @HotSpotIntrinsicCandidate
810 public static native int floatToRawIntBits(float value);
811
812 /**
813 * Returns the {@code float} value corresponding to a given
814 * bit representation.
815 * The argument is considered to be a representation of a
816 * floating-point value according to the IEEE 754 floating-point
817 * "single format" bit layout.
818 *
819 * <p>If the argument is {@code 0x7f800000}, the result is positive
820 * infinity.
821 *
822 * <p>If the argument is {@code 0xff800000}, the result is negative
823 * infinity.
824 *
825 * <p>If the argument is any value in the range
826 * {@code 0x7f800001} through {@code 0x7fffffff} or in
827 * the range {@code 0xff800001} through
828 * {@code 0xffffffff}, the result is a NaN. No IEEE 754
829 * floating-point operation provided by Java can distinguish
830 * between two NaN values of the same type with different bit
831 * patterns. Distinct values of NaN are only distinguishable by
832 * use of the {@code Float.floatToRawIntBits} method.
833 *
834 * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
835 * values that can be computed from the argument:
836 *
837 * <blockquote><pre>{@code
838 * int s = ((bits >> 31) == 0) ? 1 : -1;
839 * int e = ((bits >> 23) & 0xff);
840 * int m = (e == 0) ?
841 * (bits & 0x7fffff) << 1 :
842 * (bits & 0x7fffff) | 0x800000;
843 * }</pre></blockquote>
844 *
845 * Then the floating-point result equals the value of the mathematical
846 * expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-150</sup>.
847 *
848 * <p>Note that this method may not be able to return a
849 * {@code float} NaN with exactly same bit pattern as the
850 * {@code int} argument. IEEE 754 distinguishes between two
851 * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The
852 * differences between the two kinds of NaN are generally not
853 * visible in Java. Arithmetic operations on signaling NaNs turn
854 * them into quiet NaNs with a different, but often similar, bit
855 * pattern. However, on some processors merely copying a
856 * signaling NaN also performs that conversion. In particular,
857 * copying a signaling NaN to return it to the calling method may
858 * perform this conversion. So {@code intBitsToFloat} may
859 * not be able to return a {@code float} with a signaling NaN
860 * bit pattern. Consequently, for some {@code int} values,
861 * {@code floatToRawIntBits(intBitsToFloat(start))} may
862 * <i>not</i> equal {@code start}. Moreover, which
863 * particular bit patterns represent signaling NaNs is platform
864 * dependent; although all NaN bit patterns, quiet or signaling,
865 * must be in the NaN range identified above.
866 *
867 * @param bits an integer.
868 * @return the {@code float} floating-point value with the same bit
869 * pattern.
870 */
871 @HotSpotIntrinsicCandidate
872 public static native float intBitsToFloat(int bits);
873
874 /**
875 * Compares two {@code Float} objects numerically. There are
876 * two ways in which comparisons performed by this method differ
877 * from those performed by the Java language numerical comparison
878 * operators ({@code <, <=, ==, >=, >}) when
879 * applied to primitive {@code float} values:
880 *
881 * <ul><li>
882 * {@code Float.NaN} is considered by this method to
883 * be equal to itself and greater than all other
884 * {@code float} values
885 * (including {@code Float.POSITIVE_INFINITY}).
886 * <li>
887 * {@code 0.0f} is considered by this method to be greater
888 * than {@code -0.0f}.
889 * </ul>
890 *
891 * This ensures that the <i>natural ordering</i> of {@code Float}
892 * objects imposed by this method is <i>consistent with equals</i>.
893 *
894 * @param anotherFloat the {@code Float} to be compared.
895 * @return the value {@code 0} if {@code anotherFloat} is
896 * numerically equal to this {@code Float}; a value
897 * less than {@code 0} if this {@code Float}
898 * is numerically less than {@code anotherFloat};
899 * and a value greater than {@code 0} if this
900 * {@code Float} is numerically greater than
901 * {@code anotherFloat}.
902 *
903 * @since 1.2
904 * @see Comparable#compareTo(Object)
905 */
906 public int compareTo(Float anotherFloat) {
907 return Float.compare(value, anotherFloat.value);
908 }
909
910 /**
911 * Compares the two specified {@code float} values. The sign
912 * of the integer value returned is the same as that of the
913 * integer that would be returned by the call:
914 * <pre>
915 * new Float(f1).compareTo(new Float(f2))
916 * </pre>
917 *
918 * @param f1 the first {@code float} to compare.
919 * @param f2 the second {@code float} to compare.
920 * @return the value {@code 0} if {@code f1} is
921 * numerically equal to {@code f2}; a value less than
922 * {@code 0} if {@code f1} is numerically less than
923 * {@code f2}; and a value greater than {@code 0}
924 * if {@code f1} is numerically greater than
925 * {@code f2}.
926 * @since 1.4
927 */
928 public static int compare(float f1, float f2) {
929 if (f1 < f2)
930 return -1; // Neither val is NaN, thisVal is smaller
931 if (f1 > f2)
932 return 1; // Neither val is NaN, thisVal is larger
933
934 // Cannot use floatToRawIntBits because of possibility of NaNs.
935 int thisBits = Float.floatToIntBits(f1);
936 int anotherBits = Float.floatToIntBits(f2);
937
938 return (thisBits == anotherBits ? 0 : // Values are equal
939 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
940 1)); // (0.0, -0.0) or (NaN, !NaN)
941 }
942
943 /**
944 * Adds two {@code float} values together as per the + operator.
945 *
946 * @param a the first operand
947 * @param b the second operand
948 * @return the sum of {@code a} and {@code b}
949 * @jls 4.2.4 Floating-Point Operations
950 * @see java.util.function.BinaryOperator
951 * @since 1.8
952 */
953 public static float sum(float a, float b) {
954 return a + b;
955 }
956
957 /**
958 * Returns the greater of two {@code float} values
959 * as if by calling {@link Math#max(float, float) Math.max}.
960 *
961 * @param a the first operand
962 * @param b the second operand
963 * @return the greater of {@code a} and {@code b}
964 * @see java.util.function.BinaryOperator
965 * @since 1.8
966 */
967 public static float max(float a, float b) {
968 return Math.max(a, b);
969 }
970
971 /**
972 * Returns the smaller of two {@code float} values
973 * as if by calling {@link Math#min(float, float) Math.min}.
974 *
975 * @param a the first operand
976 * @param b the second operand
977 * @return the smaller of {@code a} and {@code b}
978 * @see java.util.function.BinaryOperator
979 * @since 1.8
980 */
981 public static float min(float a, float b) {
982 return Math.min(a, b);
983 }
984
985 /** use serialVersionUID from JDK 1.0.2 for interoperability */
986 private static final long serialVersionUID = -2671257302660747028L;
987 }