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29 * The {@code Float} class wraps a value of primitive type
30 * {@code float} in an object. An object of type
31 * {@code Float} contains a single field whose type is
34 * <p>In addition, this class provides several methods for converting a
35 * {@code float} to a {@code String} and a
36 * {@code String} to a {@code float}, as well as other
37 * constants and methods useful when dealing with a
41 * @author Arthur van Hoff
42 * @author Joseph D. Darcy
45 public final class Float extends Number implements Comparable<Float> {
47 * A constant holding the positive infinity of type
48 * {@code float}. It is equal to the value returned by
49 * {@code Float.intBitsToFloat(0x7f800000)}.
51 public static final float POSITIVE_INFINITY = 1.0f / 0.0f;
54 * A constant holding the negative infinity of type
55 * {@code float}. It is equal to the value returned by
56 * {@code Float.intBitsToFloat(0xff800000)}.
58 public static final float NEGATIVE_INFINITY = -1.0f / 0.0f;
61 * A constant holding a Not-a-Number (NaN) value of type
62 * {@code float}. It is equivalent to the value returned by
63 * {@code Float.intBitsToFloat(0x7fc00000)}.
65 public static final float NaN = 0.0f / 0.0f;
68 * A constant holding the largest positive finite value of type
69 * {@code float}, (2-2<sup>-23</sup>)·2<sup>127</sup>.
70 * It is equal to the hexadecimal floating-point literal
71 * {@code 0x1.fffffeP+127f} and also equal to
72 * {@code Float.intBitsToFloat(0x7f7fffff)}.
74 public static final float MAX_VALUE = 0x1.fffffeP+127f; // 3.4028235e+38f
77 * A constant holding the smallest positive normal value of type
78 * {@code float}, 2<sup>-126</sup>. It is equal to the
79 * hexadecimal floating-point literal {@code 0x1.0p-126f} and also
80 * equal to {@code Float.intBitsToFloat(0x00800000)}.
84 public static final float MIN_NORMAL = 0x1.0p-126f; // 1.17549435E-38f
87 * A constant holding the smallest positive nonzero value of type
88 * {@code float}, 2<sup>-149</sup>. It is equal to the
89 * hexadecimal floating-point literal {@code 0x0.000002P-126f}
90 * and also equal to {@code Float.intBitsToFloat(0x1)}.
92 public static final float MIN_VALUE = 0x0.000002P-126f; // 1.4e-45f
95 * Maximum exponent a finite {@code float} variable may have. It
96 * is equal to the value returned by {@code
97 * Math.getExponent(Float.MAX_VALUE)}.
101 public static final int MAX_EXPONENT = 127;
104 * Minimum exponent a normalized {@code float} variable may have.
105 * It is equal to the value returned by {@code
106 * Math.getExponent(Float.MIN_NORMAL)}.
110 public static final int MIN_EXPONENT = -126;
113 * The number of bits used to represent a {@code float} value.
117 public static final int SIZE = 32;
120 * The {@code Class} instance representing the primitive type
125 public static final Class<Float> TYPE = Class.getPrimitiveClass("float");
128 * Returns a string representation of the {@code float}
129 * argument. All characters mentioned below are ASCII characters.
131 * <li>If the argument is NaN, the result is the string
133 * <li>Otherwise, the result is a string that represents the sign and
134 * magnitude (absolute value) of the argument. If the sign is
135 * negative, the first character of the result is
136 * '{@code -}' (<code>'\u002D'</code>); if the sign is
137 * positive, no sign character appears in the result. As for
138 * the magnitude <i>m</i>:
140 * <li>If <i>m</i> is infinity, it is represented by the characters
141 * {@code "Infinity"}; thus, positive infinity produces
142 * the result {@code "Infinity"} and negative infinity
143 * produces the result {@code "-Infinity"}.
144 * <li>If <i>m</i> is zero, it is represented by the characters
145 * {@code "0.0"}; thus, negative zero produces the result
146 * {@code "-0.0"} and positive zero produces the result
148 * <li> If <i>m</i> is greater than or equal to 10<sup>-3</sup> but
149 * less than 10<sup>7</sup>, then it is represented as the
150 * integer part of <i>m</i>, in decimal form with no leading
151 * zeroes, followed by '{@code .}'
152 * (<code>'\u002E'</code>), followed by one or more
153 * decimal digits representing the fractional part of
155 * <li> If <i>m</i> is less than 10<sup>-3</sup> or greater than or
156 * equal to 10<sup>7</sup>, then it is represented in
157 * so-called "computerized scientific notation." Let <i>n</i>
158 * be the unique integer such that 10<sup><i>n</i> </sup>≤
159 * <i>m</i> {@literal <} 10<sup><i>n</i>+1</sup>; then let <i>a</i>
160 * be the mathematically exact quotient of <i>m</i> and
161 * 10<sup><i>n</i></sup> so that 1 ≤ <i>a</i> {@literal <} 10.
162 * The magnitude is then represented as the integer part of
163 * <i>a</i>, as a single decimal digit, followed by
164 * '{@code .}' (<code>'\u002E'</code>), followed by
165 * decimal digits representing the fractional part of
166 * <i>a</i>, followed by the letter '{@code E}'
167 * (<code>'\u0045'</code>), followed by a representation
168 * of <i>n</i> as a decimal integer, as produced by the
169 * method {@link java.lang.Integer#toString(int)}.
173 * How many digits must be printed for the fractional part of
174 * <i>m</i> or <i>a</i>? There must be at least one digit
175 * to represent the fractional part, and beyond that as many, but
176 * only as many, more digits as are needed to uniquely distinguish
177 * the argument value from adjacent values of type
178 * {@code float}. That is, suppose that <i>x</i> is the
179 * exact mathematical value represented by the decimal
180 * representation produced by this method for a finite nonzero
181 * argument <i>f</i>. Then <i>f</i> must be the {@code float}
182 * value nearest to <i>x</i>; or, if two {@code float} values are
183 * equally close to <i>x</i>, then <i>f</i> must be one of
184 * them and the least significant bit of the significand of
185 * <i>f</i> must be {@code 0}.
187 * <p>To create localized string representations of a floating-point
188 * value, use subclasses of {@link java.text.NumberFormat}.
190 * @param f the float to be converted.
191 * @return a string representation of the argument.
193 public static String toString(float f) {
194 throw new UnsupportedOperationException();
195 // return new FloatingDecimal(f).toJavaFormatString();
199 * Returns a hexadecimal string representation of the
200 * {@code float} argument. All characters mentioned below are
204 * <li>If the argument is NaN, the result is the string
206 * <li>Otherwise, the result is a string that represents the sign and
207 * magnitude (absolute value) of the argument. If the sign is negative,
208 * the first character of the result is '{@code -}'
209 * (<code>'\u002D'</code>); if the sign is positive, no sign character
210 * appears in the result. As for the magnitude <i>m</i>:
213 * <li>If <i>m</i> is infinity, it is represented by the string
214 * {@code "Infinity"}; thus, positive infinity produces the
215 * result {@code "Infinity"} and negative infinity produces
216 * the result {@code "-Infinity"}.
218 * <li>If <i>m</i> is zero, it is represented by the string
219 * {@code "0x0.0p0"}; thus, negative zero produces the result
220 * {@code "-0x0.0p0"} and positive zero produces the result
223 * <li>If <i>m</i> is a {@code float} value with a
224 * normalized representation, substrings are used to represent the
225 * significand and exponent fields. The significand is
226 * represented by the characters {@code "0x1."}
227 * followed by a lowercase hexadecimal representation of the rest
228 * of the significand as a fraction. Trailing zeros in the
229 * hexadecimal representation are removed unless all the digits
230 * are zero, in which case a single zero is used. Next, the
231 * exponent is represented by {@code "p"} followed
232 * by a decimal string of the unbiased exponent as if produced by
233 * a call to {@link Integer#toString(int) Integer.toString} on the
236 * <li>If <i>m</i> is a {@code float} value with a subnormal
237 * representation, the significand is represented by the
238 * characters {@code "0x0."} followed by a
239 * hexadecimal representation of the rest of the significand as a
240 * fraction. Trailing zeros in the hexadecimal representation are
241 * removed. Next, the exponent is represented by
242 * {@code "p-126"}. Note that there must be at
243 * least one nonzero digit in a subnormal significand.
250 * <caption><h3>Examples</h3></caption>
251 * <tr><th>Floating-point Value</th><th>Hexadecimal String</th>
252 * <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td>
253 * <tr><td>{@code -1.0}</td> <td>{@code -0x1.0p0}</td>
254 * <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td>
255 * <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td>
256 * <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td>
257 * <tr><td>{@code 0.25}</td> <td>{@code 0x1.0p-2}</td>
258 * <tr><td>{@code Float.MAX_VALUE}</td>
259 * <td>{@code 0x1.fffffep127}</td>
260 * <tr><td>{@code Minimum Normal Value}</td>
261 * <td>{@code 0x1.0p-126}</td>
262 * <tr><td>{@code Maximum Subnormal Value}</td>
263 * <td>{@code 0x0.fffffep-126}</td>
264 * <tr><td>{@code Float.MIN_VALUE}</td>
265 * <td>{@code 0x0.000002p-126}</td>
267 * @param f the {@code float} to be converted.
268 * @return a hex string representation of the argument.
270 * @author Joseph D. Darcy
272 public static String toHexString(float f) {
273 throw new UnsupportedOperationException();
274 // if (Math.abs(f) < FloatConsts.MIN_NORMAL
275 // && f != 0.0f ) {// float subnormal
276 // // Adjust exponent to create subnormal double, then
277 // // replace subnormal double exponent with subnormal float
279 // String s = Double.toHexString(FpUtils.scalb((double)f,
281 // DoubleConsts.MIN_EXPONENT-
282 // FloatConsts.MIN_EXPONENT));
283 // return s.replaceFirst("p-1022$", "p-126");
285 // else // double string will be the same as float string
286 // return Double.toHexString(f);
290 * Returns a {@code Float} object holding the
291 * {@code float} value represented by the argument string
294 * <p>If {@code s} is {@code null}, then a
295 * {@code NullPointerException} is thrown.
297 * <p>Leading and trailing whitespace characters in {@code s}
298 * are ignored. Whitespace is removed as if by the {@link
299 * String#trim} method; that is, both ASCII space and control
300 * characters are removed. The rest of {@code s} should
301 * constitute a <i>FloatValue</i> as described by the lexical
306 * <dt><i>FloatValue:</i>
307 * <dd><i>Sign<sub>opt</sub></i> {@code NaN}
308 * <dd><i>Sign<sub>opt</sub></i> {@code Infinity}
309 * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
310 * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
311 * <dd><i>SignedInteger</i>
317 * <dt><i>HexFloatingPointLiteral</i>:
318 * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
324 * <dt><i>HexSignificand:</i>
325 * <dd><i>HexNumeral</i>
326 * <dd><i>HexNumeral</i> {@code .}
327 * <dd>{@code 0x} <i>HexDigits<sub>opt</sub>
328 * </i>{@code .}<i> HexDigits</i>
329 * <dd>{@code 0X}<i> HexDigits<sub>opt</sub>
330 * </i>{@code .} <i>HexDigits</i>
336 * <dt><i>BinaryExponent:</i>
337 * <dd><i>BinaryExponentIndicator SignedInteger</i>
343 * <dt><i>BinaryExponentIndicator:</i>
350 * where <i>Sign</i>, <i>FloatingPointLiteral</i>,
351 * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
352 * <i>FloatTypeSuffix</i> are as defined in the lexical structure
354 * <cite>The Java™ Language Specification</cite>,
355 * except that underscores are not accepted between digits.
356 * If {@code s} does not have the form of
357 * a <i>FloatValue</i>, then a {@code NumberFormatException}
358 * is thrown. Otherwise, {@code s} is regarded as
359 * representing an exact decimal value in the usual
360 * "computerized scientific notation" or as an exact
361 * hexadecimal value; this exact numerical value is then
362 * conceptually converted to an "infinitely precise"
363 * binary value that is then rounded to type {@code float}
364 * by the usual round-to-nearest rule of IEEE 754 floating-point
365 * arithmetic, which includes preserving the sign of a zero
368 * Note that the round-to-nearest rule also implies overflow and
369 * underflow behaviour; if the exact value of {@code s} is large
370 * enough in magnitude (greater than or equal to ({@link
371 * #MAX_VALUE} + {@link Math#ulp(float) ulp(MAX_VALUE)}/2),
372 * rounding to {@code float} will result in an infinity and if the
373 * exact value of {@code s} is small enough in magnitude (less
374 * than or equal to {@link #MIN_VALUE}/2), rounding to float will
377 * Finally, after rounding a {@code Float} object representing
378 * this {@code float} value is returned.
380 * <p>To interpret localized string representations of a
381 * floating-point value, use subclasses of {@link
382 * java.text.NumberFormat}.
384 * <p>Note that trailing format specifiers, specifiers that
385 * determine the type of a floating-point literal
386 * ({@code 1.0f} is a {@code float} value;
387 * {@code 1.0d} is a {@code double} value), do
388 * <em>not</em> influence the results of this method. In other
389 * words, the numerical value of the input string is converted
390 * directly to the target floating-point type. In general, the
391 * two-step sequence of conversions, string to {@code double}
392 * followed by {@code double} to {@code float}, is
393 * <em>not</em> equivalent to converting a string directly to
394 * {@code float}. For example, if first converted to an
395 * intermediate {@code double} and then to
396 * {@code float}, the string<br>
397 * {@code "1.00000017881393421514957253748434595763683319091796875001d"}<br>
398 * results in the {@code float} value
399 * {@code 1.0000002f}; if the string is converted directly to
400 * {@code float}, <code>1.000000<b>1</b>f</code> results.
402 * <p>To avoid calling this method on an invalid string and having
403 * a {@code NumberFormatException} be thrown, the documentation
404 * for {@link Double#valueOf Double.valueOf} lists a regular
405 * expression which can be used to screen the input.
407 * @param s the string to be parsed.
408 * @return a {@code Float} object holding the value
409 * represented by the {@code String} argument.
410 * @throws NumberFormatException if the string does not contain a
413 public static Float valueOf(String s) throws NumberFormatException {
414 throw new UnsupportedOperationException();
415 // return new Float(FloatingDecimal.readJavaFormatString(s).floatValue());
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 public static float parseFloat(String s) throws NumberFormatException {
450 throw new UnsupportedOperationException();
451 // return FloatingDecimal.readJavaFormatString(s).floatValue();
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 throw new UnsupportedOperationException();
713 // int result = floatToRawIntBits(value);
714 // // Check for NaN based on values of bit fields, maximum
715 // // exponent and nonzero significand.
716 // if ( ((result & FloatConsts.EXP_BIT_MASK) ==
717 // FloatConsts.EXP_BIT_MASK) &&
718 // (result & FloatConsts.SIGNIF_BIT_MASK) != 0)
719 // result = 0x7fc00000;
724 * Returns a representation of the specified floating-point value
725 * according to the IEEE 754 floating-point "single format" bit
726 * layout, preserving Not-a-Number (NaN) values.
728 * <p>Bit 31 (the bit that is selected by the mask
729 * {@code 0x80000000}) represents the sign of the floating-point
731 * Bits 30-23 (the bits that are selected by the mask
732 * {@code 0x7f800000}) represent the exponent.
733 * Bits 22-0 (the bits that are selected by the mask
734 * {@code 0x007fffff}) represent the significand (sometimes called
735 * the mantissa) of the floating-point number.
737 * <p>If the argument is positive infinity, the result is
738 * {@code 0x7f800000}.
740 * <p>If the argument is negative infinity, the result is
741 * {@code 0xff800000}.
743 * <p>If the argument is NaN, the result is the integer representing
744 * the actual NaN value. Unlike the {@code floatToIntBits}
745 * method, {@code floatToRawIntBits} does not collapse all the
746 * bit patterns encoding a NaN to a single "canonical"
749 * <p>In all cases, the result is an integer that, when given to the
750 * {@link #intBitsToFloat(int)} method, will produce a
751 * floating-point value the same as the argument to
752 * {@code floatToRawIntBits}.
754 * @param value a floating-point number.
755 * @return the bits that represent the floating-point number.
758 public static native int floatToRawIntBits(float value);
761 * Returns the {@code float} value corresponding to a given
762 * bit representation.
763 * The argument is considered to be a representation of a
764 * floating-point value according to the IEEE 754 floating-point
765 * "single format" bit layout.
767 * <p>If the argument is {@code 0x7f800000}, the result is positive
770 * <p>If the argument is {@code 0xff800000}, the result is negative
773 * <p>If the argument is any value in the range
774 * {@code 0x7f800001} through {@code 0x7fffffff} or in
775 * the range {@code 0xff800001} through
776 * {@code 0xffffffff}, the result is a NaN. No IEEE 754
777 * floating-point operation provided by Java can distinguish
778 * between two NaN values of the same type with different bit
779 * patterns. Distinct values of NaN are only distinguishable by
780 * use of the {@code Float.floatToRawIntBits} method.
782 * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
783 * values that can be computed from the argument:
786 * int s = ((bits >> 31) == 0) ? 1 : -1;
787 * int e = ((bits >> 23) & 0xff);
789 * (bits & 0x7fffff) << 1 :
790 * (bits & 0x7fffff) | 0x800000;
791 * </pre></blockquote>
793 * Then the floating-point result equals the value of the mathematical
794 * expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-150</sup>.
796 * <p>Note that this method may not be able to return a
797 * {@code float} NaN with exactly same bit pattern as the
798 * {@code int} argument. IEEE 754 distinguishes between two
799 * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The
800 * differences between the two kinds of NaN are generally not
801 * visible in Java. Arithmetic operations on signaling NaNs turn
802 * them into quiet NaNs with a different, but often similar, bit
803 * pattern. However, on some processors merely copying a
804 * signaling NaN also performs that conversion. In particular,
805 * copying a signaling NaN to return it to the calling method may
806 * perform this conversion. So {@code intBitsToFloat} may
807 * not be able to return a {@code float} with a signaling NaN
808 * bit pattern. Consequently, for some {@code int} values,
809 * {@code floatToRawIntBits(intBitsToFloat(start))} may
810 * <i>not</i> equal {@code start}. Moreover, which
811 * particular bit patterns represent signaling NaNs is platform
812 * dependent; although all NaN bit patterns, quiet or signaling,
813 * must be in the NaN range identified above.
815 * @param bits an integer.
816 * @return the {@code float} floating-point value with the same bit
819 public static native float intBitsToFloat(int bits);
822 * Compares two {@code Float} objects numerically. There are
823 * two ways in which comparisons performed by this method differ
824 * from those performed by the Java language numerical comparison
825 * operators ({@code <, <=, ==, >=, >}) when
826 * applied to primitive {@code float} values:
829 * {@code Float.NaN} is considered by this method to
830 * be equal to itself and greater than all other
831 * {@code float} values
832 * (including {@code Float.POSITIVE_INFINITY}).
834 * {@code 0.0f} is considered by this method to be greater
835 * than {@code -0.0f}.
838 * This ensures that the <i>natural ordering</i> of {@code Float}
839 * objects imposed by this method is <i>consistent with equals</i>.
841 * @param anotherFloat the {@code Float} to be compared.
842 * @return the value {@code 0} if {@code anotherFloat} is
843 * numerically equal to this {@code Float}; a value
844 * less than {@code 0} if this {@code Float}
845 * is numerically less than {@code anotherFloat};
846 * and a value greater than {@code 0} if this
847 * {@code Float} is numerically greater than
848 * {@code anotherFloat}.
851 * @see Comparable#compareTo(Object)
853 public int compareTo(Float anotherFloat) {
854 return Float.compare(value, anotherFloat.value);
858 * Compares the two specified {@code float} values. The sign
859 * of the integer value returned is the same as that of the
860 * integer that would be returned by the call:
862 * new Float(f1).compareTo(new Float(f2))
865 * @param f1 the first {@code float} to compare.
866 * @param f2 the second {@code float} to compare.
867 * @return the value {@code 0} if {@code f1} is
868 * numerically equal to {@code f2}; a value less than
869 * {@code 0} if {@code f1} is numerically less than
870 * {@code f2}; and a value greater than {@code 0}
871 * if {@code f1} is numerically greater than
875 public static int compare(float f1, float f2) {
877 return -1; // Neither val is NaN, thisVal is smaller
879 return 1; // Neither val is NaN, thisVal is larger
881 // Cannot use floatToRawIntBits because of possibility of NaNs.
882 int thisBits = Float.floatToIntBits(f1);
883 int anotherBits = Float.floatToIntBits(f2);
885 return (thisBits == anotherBits ? 0 : // Values are equal
886 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
887 1)); // (0.0, -0.0) or (NaN, !NaN)
890 /** use serialVersionUID from JDK 1.0.2 for interoperability */
891 private static final long serialVersionUID = -2671257302660747028L;