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28 import org.apidesign.bck2brwsr.core.JavaScriptBody;
31 * The {@code Float} class wraps a value of primitive type
32 * {@code float} in an object. An object of type
33 * {@code Float} contains a single field whose type is
36 * <p>In addition, this class provides several methods for converting a
37 * {@code float} to a {@code String} and a
38 * {@code String} to a {@code float}, as well as other
39 * constants and methods useful when dealing with a
43 * @author Arthur van Hoff
44 * @author Joseph D. Darcy
47 public final class Float extends Number implements Comparable<Float> {
49 * A constant holding the positive infinity of type
50 * {@code float}. It is equal to the value returned by
51 * {@code Float.intBitsToFloat(0x7f800000)}.
53 public static final float POSITIVE_INFINITY = 1.0f / 0.0f;
56 * A constant holding the negative infinity of type
57 * {@code float}. It is equal to the value returned by
58 * {@code Float.intBitsToFloat(0xff800000)}.
60 public static final float NEGATIVE_INFINITY = -1.0f / 0.0f;
63 * A constant holding a Not-a-Number (NaN) value of type
64 * {@code float}. It is equivalent to the value returned by
65 * {@code Float.intBitsToFloat(0x7fc00000)}.
67 public static final float NaN = 0.0f / 0.0f;
70 * A constant holding the largest positive finite value of type
71 * {@code float}, (2-2<sup>-23</sup>)·2<sup>127</sup>.
72 * It is equal to the hexadecimal floating-point literal
73 * {@code 0x1.fffffeP+127f} and also equal to
74 * {@code Float.intBitsToFloat(0x7f7fffff)}.
76 public static final float MAX_VALUE = 0x1.fffffeP+127f; // 3.4028235e+38f
79 * A constant holding the smallest positive normal value of type
80 * {@code float}, 2<sup>-126</sup>. It is equal to the
81 * hexadecimal floating-point literal {@code 0x1.0p-126f} and also
82 * equal to {@code Float.intBitsToFloat(0x00800000)}.
86 public static final float MIN_NORMAL = 0x1.0p-126f; // 1.17549435E-38f
89 * A constant holding the smallest positive nonzero value of type
90 * {@code float}, 2<sup>-149</sup>. It is equal to the
91 * hexadecimal floating-point literal {@code 0x0.000002P-126f}
92 * and also equal to {@code Float.intBitsToFloat(0x1)}.
94 public static final float MIN_VALUE = 0x0.000002P-126f; // 1.4e-45f
97 * Maximum exponent a finite {@code float} variable may have. It
98 * is equal to the value returned by {@code
99 * Math.getExponent(Float.MAX_VALUE)}.
103 public static final int MAX_EXPONENT = 127;
106 * Minimum exponent a normalized {@code float} variable may have.
107 * It is equal to the value returned by {@code
108 * Math.getExponent(Float.MIN_NORMAL)}.
112 public static final int MIN_EXPONENT = -126;
115 * The number of bits used to represent a {@code float} value.
119 public static final int SIZE = 32;
122 * The {@code Class} instance representing the primitive type
127 public static final Class<Float> TYPE = Class.getPrimitiveClass("float");
130 * Returns a string representation of the {@code float}
131 * argument. All characters mentioned below are ASCII characters.
133 * <li>If the argument is NaN, the result is the string
135 * <li>Otherwise, the result is a string that represents the sign and
136 * magnitude (absolute value) of the argument. If the sign is
137 * negative, the first character of the result is
138 * '{@code -}' (<code>'\u002D'</code>); if the sign is
139 * positive, no sign character appears in the result. As for
140 * the magnitude <i>m</i>:
142 * <li>If <i>m</i> is infinity, it is represented by the characters
143 * {@code "Infinity"}; thus, positive infinity produces
144 * the result {@code "Infinity"} and negative infinity
145 * produces the result {@code "-Infinity"}.
146 * <li>If <i>m</i> is zero, it is represented by the characters
147 * {@code "0.0"}; thus, negative zero produces the result
148 * {@code "-0.0"} and positive zero produces the result
150 * <li> If <i>m</i> is greater than or equal to 10<sup>-3</sup> but
151 * less than 10<sup>7</sup>, then it is represented as the
152 * integer part of <i>m</i>, in decimal form with no leading
153 * zeroes, followed by '{@code .}'
154 * (<code>'\u002E'</code>), followed by one or more
155 * decimal digits representing the fractional part of
157 * <li> If <i>m</i> is less than 10<sup>-3</sup> or greater than or
158 * equal to 10<sup>7</sup>, then it is represented in
159 * so-called "computerized scientific notation." Let <i>n</i>
160 * be the unique integer such that 10<sup><i>n</i> </sup>≤
161 * <i>m</i> {@literal <} 10<sup><i>n</i>+1</sup>; then let <i>a</i>
162 * be the mathematically exact quotient of <i>m</i> and
163 * 10<sup><i>n</i></sup> so that 1 ≤ <i>a</i> {@literal <} 10.
164 * The magnitude is then represented as the integer part of
165 * <i>a</i>, as a single decimal digit, followed by
166 * '{@code .}' (<code>'\u002E'</code>), followed by
167 * decimal digits representing the fractional part of
168 * <i>a</i>, followed by the letter '{@code E}'
169 * (<code>'\u0045'</code>), followed by a representation
170 * of <i>n</i> as a decimal integer, as produced by the
171 * method {@link java.lang.Integer#toString(int)}.
175 * How many digits must be printed for the fractional part of
176 * <i>m</i> or <i>a</i>? There must be at least one digit
177 * to represent the fractional part, and beyond that as many, but
178 * only as many, more digits as are needed to uniquely distinguish
179 * the argument value from adjacent values of type
180 * {@code float}. That is, suppose that <i>x</i> is the
181 * exact mathematical value represented by the decimal
182 * representation produced by this method for a finite nonzero
183 * argument <i>f</i>. Then <i>f</i> must be the {@code float}
184 * value nearest to <i>x</i>; or, if two {@code float} values are
185 * equally close to <i>x</i>, then <i>f</i> must be one of
186 * them and the least significant bit of the significand of
187 * <i>f</i> must be {@code 0}.
189 * <p>To create localized string representations of a floating-point
190 * value, use subclasses of {@link java.text.NumberFormat}.
192 * @param f the float to be converted.
193 * @return a string representation of the argument.
195 public static String toString(float f) {
196 return Double.toString(f);
200 * Returns a hexadecimal string representation of the
201 * {@code float} argument. All characters mentioned below are
205 * <li>If the argument is NaN, the result is the string
207 * <li>Otherwise, the result is a string that represents the sign and
208 * magnitude (absolute value) of the argument. If the sign is negative,
209 * the first character of the result is '{@code -}'
210 * (<code>'\u002D'</code>); if the sign is positive, no sign character
211 * appears in the result. As for the magnitude <i>m</i>:
214 * <li>If <i>m</i> is infinity, it is represented by the string
215 * {@code "Infinity"}; thus, positive infinity produces the
216 * result {@code "Infinity"} and negative infinity produces
217 * the result {@code "-Infinity"}.
219 * <li>If <i>m</i> is zero, it is represented by the string
220 * {@code "0x0.0p0"}; thus, negative zero produces the result
221 * {@code "-0x0.0p0"} and positive zero produces the result
224 * <li>If <i>m</i> is a {@code float} value with a
225 * normalized representation, substrings are used to represent the
226 * significand and exponent fields. The significand is
227 * represented by the characters {@code "0x1."}
228 * followed by a lowercase hexadecimal representation of the rest
229 * of the significand as a fraction. Trailing zeros in the
230 * hexadecimal representation are removed unless all the digits
231 * are zero, in which case a single zero is used. Next, the
232 * exponent is represented by {@code "p"} followed
233 * by a decimal string of the unbiased exponent as if produced by
234 * a call to {@link Integer#toString(int) Integer.toString} on the
237 * <li>If <i>m</i> is a {@code float} value with a subnormal
238 * representation, the significand is represented by the
239 * characters {@code "0x0."} followed by a
240 * hexadecimal representation of the rest of the significand as a
241 * fraction. Trailing zeros in the hexadecimal representation are
242 * removed. Next, the exponent is represented by
243 * {@code "p-126"}. Note that there must be at
244 * least one nonzero digit in a subnormal significand.
251 * <caption><h3>Examples</h3></caption>
252 * <tr><th>Floating-point Value</th><th>Hexadecimal String</th>
253 * <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td>
254 * <tr><td>{@code -1.0}</td> <td>{@code -0x1.0p0}</td>
255 * <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td>
256 * <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td>
257 * <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td>
258 * <tr><td>{@code 0.25}</td> <td>{@code 0x1.0p-2}</td>
259 * <tr><td>{@code Float.MAX_VALUE}</td>
260 * <td>{@code 0x1.fffffep127}</td>
261 * <tr><td>{@code Minimum Normal Value}</td>
262 * <td>{@code 0x1.0p-126}</td>
263 * <tr><td>{@code Maximum Subnormal Value}</td>
264 * <td>{@code 0x0.fffffep-126}</td>
265 * <tr><td>{@code Float.MIN_VALUE}</td>
266 * <td>{@code 0x0.000002p-126}</td>
268 * @param f the {@code float} to be converted.
269 * @return a hex string representation of the argument.
271 * @author Joseph D. Darcy
273 public static String toHexString(float f) {
274 throw new UnsupportedOperationException();
275 // if (Math.abs(f) < FloatConsts.MIN_NORMAL
276 // && f != 0.0f ) {// float subnormal
277 // // Adjust exponent to create subnormal double, then
278 // // replace subnormal double exponent with subnormal float
280 // String s = Double.toHexString(FpUtils.scalb((double)f,
282 // DoubleConsts.MIN_EXPONENT-
283 // FloatConsts.MIN_EXPONENT));
284 // return s.replaceFirst("p-1022$", "p-126");
286 // else // double string will be the same as float string
287 // return Double.toHexString(f);
291 * Returns a {@code Float} object holding the
292 * {@code float} value represented by the argument string
295 * <p>If {@code s} is {@code null}, then a
296 * {@code NullPointerException} is thrown.
298 * <p>Leading and trailing whitespace characters in {@code s}
299 * are ignored. Whitespace is removed as if by the {@link
300 * String#trim} method; that is, both ASCII space and control
301 * characters are removed. The rest of {@code s} should
302 * constitute a <i>FloatValue</i> as described by the lexical
307 * <dt><i>FloatValue:</i>
308 * <dd><i>Sign<sub>opt</sub></i> {@code NaN}
309 * <dd><i>Sign<sub>opt</sub></i> {@code Infinity}
310 * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
311 * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
312 * <dd><i>SignedInteger</i>
318 * <dt><i>HexFloatingPointLiteral</i>:
319 * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
325 * <dt><i>HexSignificand:</i>
326 * <dd><i>HexNumeral</i>
327 * <dd><i>HexNumeral</i> {@code .}
328 * <dd>{@code 0x} <i>HexDigits<sub>opt</sub>
329 * </i>{@code .}<i> HexDigits</i>
330 * <dd>{@code 0X}<i> HexDigits<sub>opt</sub>
331 * </i>{@code .} <i>HexDigits</i>
337 * <dt><i>BinaryExponent:</i>
338 * <dd><i>BinaryExponentIndicator SignedInteger</i>
344 * <dt><i>BinaryExponentIndicator:</i>
351 * where <i>Sign</i>, <i>FloatingPointLiteral</i>,
352 * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
353 * <i>FloatTypeSuffix</i> are as defined in the lexical structure
355 * <cite>The Java™ Language Specification</cite>,
356 * except that underscores are not accepted between digits.
357 * If {@code s} does not have the form of
358 * a <i>FloatValue</i>, then a {@code NumberFormatException}
359 * is thrown. Otherwise, {@code s} is regarded as
360 * representing an exact decimal value in the usual
361 * "computerized scientific notation" or as an exact
362 * hexadecimal value; this exact numerical value is then
363 * conceptually converted to an "infinitely precise"
364 * binary value that is then rounded to type {@code float}
365 * by the usual round-to-nearest rule of IEEE 754 floating-point
366 * arithmetic, which includes preserving the sign of a zero
369 * Note that the round-to-nearest rule also implies overflow and
370 * underflow behaviour; if the exact value of {@code s} is large
371 * enough in magnitude (greater than or equal to ({@link
372 * #MAX_VALUE} + {@link Math#ulp(float) ulp(MAX_VALUE)}/2),
373 * rounding to {@code float} will result in an infinity and if the
374 * exact value of {@code s} is small enough in magnitude (less
375 * than or equal to {@link #MIN_VALUE}/2), rounding to float will
378 * Finally, after rounding a {@code Float} object representing
379 * this {@code float} value is returned.
381 * <p>To interpret localized string representations of a
382 * floating-point value, use subclasses of {@link
383 * java.text.NumberFormat}.
385 * <p>Note that trailing format specifiers, specifiers that
386 * determine the type of a floating-point literal
387 * ({@code 1.0f} is a {@code float} value;
388 * {@code 1.0d} is a {@code double} value), do
389 * <em>not</em> influence the results of this method. In other
390 * words, the numerical value of the input string is converted
391 * directly to the target floating-point type. In general, the
392 * two-step sequence of conversions, string to {@code double}
393 * followed by {@code double} to {@code float}, is
394 * <em>not</em> equivalent to converting a string directly to
395 * {@code float}. For example, if first converted to an
396 * intermediate {@code double} and then to
397 * {@code float}, the string<br>
398 * {@code "1.00000017881393421514957253748434595763683319091796875001d"}<br>
399 * results in the {@code float} value
400 * {@code 1.0000002f}; if the string is converted directly to
401 * {@code float}, <code>1.000000<b>1</b>f</code> results.
403 * <p>To avoid calling this method on an invalid string and having
404 * a {@code NumberFormatException} be thrown, the documentation
405 * for {@link Double#valueOf Double.valueOf} lists a regular
406 * expression which can be used to screen the input.
408 * @param s the string to be parsed.
409 * @return a {@code Float} object holding the value
410 * represented by the {@code String} argument.
411 * @throws NumberFormatException if the string does not contain a
414 public static Float valueOf(String s) throws NumberFormatException {
415 return new Float(parseFloat(s));
419 * Returns a {@code Float} instance representing the specified
420 * {@code float} value.
421 * If a new {@code Float} instance is not required, this method
422 * should generally be used in preference to the constructor
423 * {@link #Float(float)}, as this method is likely to yield
424 * significantly better space and time performance by caching
425 * frequently requested values.
427 * @param f a float value.
428 * @return a {@code Float} instance representing {@code f}.
431 public static Float valueOf(float f) {
436 * Returns a new {@code float} initialized to the value
437 * represented by the specified {@code String}, as performed
438 * by the {@code valueOf} method of class {@code Float}.
440 * @param s the string to be parsed.
441 * @return the {@code float} value represented by the string
443 * @throws NullPointerException if the string is null
444 * @throws NumberFormatException if the string does not contain a
445 * parsable {@code float}.
446 * @see java.lang.Float#valueOf(String)
449 @JavaScriptBody(args="s", body="return parseFloat(s);")
450 public static float parseFloat(String s) throws NumberFormatException {
455 * Returns {@code true} if the specified number is a
456 * Not-a-Number (NaN) value, {@code false} otherwise.
458 * @param v the value to be tested.
459 * @return {@code true} if the argument is NaN;
460 * {@code false} otherwise.
462 static public boolean isNaN(float v) {
467 * Returns {@code true} if the specified number is infinitely
468 * large in magnitude, {@code false} otherwise.
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.
474 static public boolean isInfinite(float v) {
475 return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
479 * The value of the Float.
483 private final float value;
486 * Constructs a newly allocated {@code Float} object that
487 * represents the primitive {@code float} argument.
489 * @param value the value to be represented by the {@code Float}.
491 public Float(float value) {
496 * Constructs a newly allocated {@code Float} object that
497 * represents the argument converted to type {@code float}.
499 * @param value the value to be represented by the {@code Float}.
501 public Float(double value) {
502 this.value = (float)value;
506 * Constructs a newly allocated {@code Float} object that
507 * represents the floating-point value of type {@code float}
508 * represented by the string. The string is converted to a
509 * {@code float} value as if by the {@code valueOf} method.
511 * @param s a string to be converted to a {@code Float}.
512 * @throws NumberFormatException if the string does not contain a
514 * @see java.lang.Float#valueOf(java.lang.String)
516 public Float(String s) throws NumberFormatException {
517 // REMIND: this is inefficient
518 this(valueOf(s).floatValue());
522 * Returns {@code true} if this {@code Float} value is a
523 * Not-a-Number (NaN), {@code false} otherwise.
525 * @return {@code true} if the value represented by this object is
526 * NaN; {@code false} otherwise.
528 public boolean isNaN() {
533 * Returns {@code true} if this {@code Float} value is
534 * infinitely large in magnitude, {@code false} otherwise.
536 * @return {@code true} if the value represented by this object is
537 * positive infinity or negative infinity;
538 * {@code false} otherwise.
540 public boolean isInfinite() {
541 return isInfinite(value);
545 * Returns a string representation of this {@code Float} object.
546 * The primitive {@code float} value represented by this object
547 * is converted to a {@code String} exactly as if by the method
548 * {@code toString} of one argument.
550 * @return a {@code String} representation of this object.
551 * @see java.lang.Float#toString(float)
553 public String toString() {
554 return Float.toString(value);
558 * Returns the value of this {@code Float} as a {@code byte} (by
559 * casting to a {@code byte}).
561 * @return the {@code float} value represented by this object
562 * converted to type {@code byte}
564 public byte byteValue() {
569 * Returns the value of this {@code Float} as a {@code short} (by
570 * casting to a {@code short}).
572 * @return the {@code float} value represented by this object
573 * converted to type {@code short}
576 public short shortValue() {
581 * Returns the value of this {@code Float} as an {@code int} (by
582 * casting to type {@code int}).
584 * @return the {@code float} value represented by this object
585 * converted to type {@code int}
587 public int intValue() {
592 * Returns value of this {@code Float} as a {@code long} (by
593 * casting to type {@code long}).
595 * @return the {@code float} value represented by this object
596 * converted to type {@code long}
598 public long longValue() {
603 * Returns the {@code float} value of this {@code Float} object.
605 * @return the {@code float} value represented by this object
607 public float floatValue() {
612 * Returns the {@code double} value of this {@code Float} object.
614 * @return the {@code float} value represented by this
615 * object is converted to type {@code double} and the
616 * result of the conversion is returned.
618 public double doubleValue() {
619 return (double)value;
623 * Returns a hash code for this {@code Float} object. The
624 * result is the integer bit representation, exactly as produced
625 * by the method {@link #floatToIntBits(float)}, of the primitive
626 * {@code float} value represented by this {@code Float}
629 * @return a hash code value for this object.
631 public int hashCode() {
632 return floatToIntBits(value);
637 * Compares this object against the specified object. The result
638 * is {@code true} if and only if the argument is not
639 * {@code null} and is a {@code Float} object that
640 * represents a {@code float} with the same value as the
641 * {@code float} represented by this object. For this
642 * purpose, two {@code float} values are considered to be the
643 * same if and only if the method {@link #floatToIntBits(float)}
644 * returns the identical {@code int} value when applied to
647 * <p>Note that in most cases, for two instances of class
648 * {@code Float}, {@code f1} and {@code f2}, the value
649 * of {@code f1.equals(f2)} is {@code true} if and only if
652 * f1.floatValue() == f2.floatValue()
653 * </pre></blockquote>
655 * <p>also has the value {@code true}. However, there are two exceptions:
657 * <li>If {@code f1} and {@code f2} both represent
658 * {@code Float.NaN}, then the {@code equals} method returns
659 * {@code true}, even though {@code Float.NaN==Float.NaN}
660 * has the value {@code false}.
661 * <li>If {@code f1} represents {@code +0.0f} while
662 * {@code f2} represents {@code -0.0f}, or vice
663 * versa, the {@code equal} test has the value
664 * {@code false}, even though {@code 0.0f==-0.0f}
665 * has the value {@code true}.
668 * This definition allows hash tables to operate properly.
670 * @param obj the object to be compared
671 * @return {@code true} if the objects are the same;
672 * {@code false} otherwise.
673 * @see java.lang.Float#floatToIntBits(float)
675 public boolean equals(Object obj) {
676 return (obj instanceof Float)
677 && (floatToIntBits(((Float)obj).value) == floatToIntBits(value));
681 * Returns a representation of the specified floating-point value
682 * according to the IEEE 754 floating-point "single format" bit
685 * <p>Bit 31 (the bit that is selected by the mask
686 * {@code 0x80000000}) represents the sign of the floating-point
688 * Bits 30-23 (the bits that are selected by the mask
689 * {@code 0x7f800000}) represent the exponent.
690 * Bits 22-0 (the bits that are selected by the mask
691 * {@code 0x007fffff}) represent the significand (sometimes called
692 * the mantissa) of the floating-point number.
694 * <p>If the argument is positive infinity, the result is
695 * {@code 0x7f800000}.
697 * <p>If the argument is negative infinity, the result is
698 * {@code 0xff800000}.
700 * <p>If the argument is NaN, the result is {@code 0x7fc00000}.
702 * <p>In all cases, the result is an integer that, when given to the
703 * {@link #intBitsToFloat(int)} method, will produce a floating-point
704 * value the same as the argument to {@code floatToIntBits}
705 * (except all NaN values are collapsed to a single
706 * "canonical" NaN value).
708 * @param value a floating-point number.
709 * @return the bits that represent the floating-point number.
711 public static int floatToIntBits(float value) {
712 final int EXP_BIT_MASK = 2139095040;
713 final int SIGNIF_BIT_MASK = 8388607;
715 int result = floatToRawIntBits(value);
716 // Check for NaN based on values of bit fields, maximum
717 // exponent and nonzero significand.
718 if ( ((result & EXP_BIT_MASK) ==
720 (result & SIGNIF_BIT_MASK) != 0)
726 * Returns a representation of the specified floating-point value
727 * according to the IEEE 754 floating-point "single format" bit
728 * layout, preserving Not-a-Number (NaN) values.
730 * <p>Bit 31 (the bit that is selected by the mask
731 * {@code 0x80000000}) represents the sign of the floating-point
733 * Bits 30-23 (the bits that are selected by the mask
734 * {@code 0x7f800000}) represent the exponent.
735 * Bits 22-0 (the bits that are selected by the mask
736 * {@code 0x007fffff}) represent the significand (sometimes called
737 * the mantissa) of the floating-point number.
739 * <p>If the argument is positive infinity, the result is
740 * {@code 0x7f800000}.
742 * <p>If the argument is negative infinity, the result is
743 * {@code 0xff800000}.
745 * <p>If the argument is NaN, the result is the integer representing
746 * the actual NaN value. Unlike the {@code floatToIntBits}
747 * method, {@code floatToRawIntBits} does not collapse all the
748 * bit patterns encoding a NaN to a single "canonical"
751 * <p>In all cases, the result is an integer that, when given to the
752 * {@link #intBitsToFloat(int)} method, will produce a
753 * floating-point value the same as the argument to
754 * {@code floatToRawIntBits}.
756 * @param value a floating-point number.
757 * @return the bits that represent the floating-point number.
760 @JavaScriptBody(args = { "value" }, body = ""
761 + "var a = new ArrayBuffer(4);"
762 + "new Float32Array(a)[0] = value;"
763 + "return new Int32Array(a)[0];"
765 public static native int floatToRawIntBits(float value);
768 * Returns the {@code float} value corresponding to a given
769 * bit representation.
770 * The argument is considered to be a representation of a
771 * floating-point value according to the IEEE 754 floating-point
772 * "single format" bit layout.
774 * <p>If the argument is {@code 0x7f800000}, the result is positive
777 * <p>If the argument is {@code 0xff800000}, the result is negative
780 * <p>If the argument is any value in the range
781 * {@code 0x7f800001} through {@code 0x7fffffff} or in
782 * the range {@code 0xff800001} through
783 * {@code 0xffffffff}, the result is a NaN. No IEEE 754
784 * floating-point operation provided by Java can distinguish
785 * between two NaN values of the same type with different bit
786 * patterns. Distinct values of NaN are only distinguishable by
787 * use of the {@code Float.floatToRawIntBits} method.
789 * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
790 * values that can be computed from the argument:
793 * int s = ((bits >> 31) == 0) ? 1 : -1;
794 * int e = ((bits >> 23) & 0xff);
796 * (bits & 0x7fffff) << 1 :
797 * (bits & 0x7fffff) | 0x800000;
798 * </pre></blockquote>
800 * Then the floating-point result equals the value of the mathematical
801 * expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-150</sup>.
803 * <p>Note that this method may not be able to return a
804 * {@code float} NaN with exactly same bit pattern as the
805 * {@code int} argument. IEEE 754 distinguishes between two
806 * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The
807 * differences between the two kinds of NaN are generally not
808 * visible in Java. Arithmetic operations on signaling NaNs turn
809 * them into quiet NaNs with a different, but often similar, bit
810 * pattern. However, on some processors merely copying a
811 * signaling NaN also performs that conversion. In particular,
812 * copying a signaling NaN to return it to the calling method may
813 * perform this conversion. So {@code intBitsToFloat} may
814 * not be able to return a {@code float} with a signaling NaN
815 * bit pattern. Consequently, for some {@code int} values,
816 * {@code floatToRawIntBits(intBitsToFloat(start))} may
817 * <i>not</i> equal {@code start}. Moreover, which
818 * particular bit patterns represent signaling NaNs is platform
819 * dependent; although all NaN bit patterns, quiet or signaling,
820 * must be in the NaN range identified above.
822 * @param bits an integer.
823 * @return the {@code float} floating-point value with the same bit
826 @JavaScriptBody(args = "bits",
828 "var s = ((bits >> 31) == 0) ? 1 : -1;\n"
829 + "var e = ((bits >> 23) & 0xff);\n"
830 + "if (e === 0xff) {\n"
831 + " if ((bits & 0x7fffff) === 0) {\n"
832 + " return (s > 0) ? Number.POSITIVE_INFINITY"
833 + " : Number.NEGATIVE_INFINITY;\n"
835 + " return Number.NaN;\n"
837 + "var m = (e === 0) ?\n"
838 + " (bits & 0x7fffff) << 1 :\n"
839 + " (bits & 0x7fffff) | 0x800000;\n"
840 + "return s * m * Math.pow(2.0, e - 150);\n"
842 public static native float intBitsToFloat(int bits);
845 * Compares two {@code Float} objects numerically. There are
846 * two ways in which comparisons performed by this method differ
847 * from those performed by the Java language numerical comparison
848 * operators ({@code <, <=, ==, >=, >}) when
849 * applied to primitive {@code float} values:
852 * {@code Float.NaN} is considered by this method to
853 * be equal to itself and greater than all other
854 * {@code float} values
855 * (including {@code Float.POSITIVE_INFINITY}).
857 * {@code 0.0f} is considered by this method to be greater
858 * than {@code -0.0f}.
861 * This ensures that the <i>natural ordering</i> of {@code Float}
862 * objects imposed by this method is <i>consistent with equals</i>.
864 * @param anotherFloat the {@code Float} to be compared.
865 * @return the value {@code 0} if {@code anotherFloat} is
866 * numerically equal to this {@code Float}; a value
867 * less than {@code 0} if this {@code Float}
868 * is numerically less than {@code anotherFloat};
869 * and a value greater than {@code 0} if this
870 * {@code Float} is numerically greater than
871 * {@code anotherFloat}.
874 * @see Comparable#compareTo(Object)
876 public int compareTo(Float anotherFloat) {
877 return Float.compare(value, anotherFloat.value);
881 * Compares the two specified {@code float} values. The sign
882 * of the integer value returned is the same as that of the
883 * integer that would be returned by the call:
885 * new Float(f1).compareTo(new Float(f2))
888 * @param f1 the first {@code float} to compare.
889 * @param f2 the second {@code float} to compare.
890 * @return the value {@code 0} if {@code f1} is
891 * numerically equal to {@code f2}; a value less than
892 * {@code 0} if {@code f1} is numerically less than
893 * {@code f2}; and a value greater than {@code 0}
894 * if {@code f1} is numerically greater than
898 public static int compare(float f1, float f2) {
900 return -1; // Neither val is NaN, thisVal is smaller
902 return 1; // Neither val is NaN, thisVal is larger
904 // Cannot use floatToRawIntBits because of possibility of NaNs.
905 int thisBits = Float.floatToIntBits(f1);
906 int anotherBits = Float.floatToIntBits(f2);
908 return (thisBits == anotherBits ? 0 : // Values are equal
909 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
910 1)); // (0.0, -0.0) or (NaN, !NaN)
913 /** use serialVersionUID from JDK 1.0.2 for interoperability */
914 private static final long serialVersionUID = -2671257302660747028L;