java.lang.Float Maven / Gradle / Ivy
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
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* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
package java.lang;
import org.apidesign.bck2brwsr.core.JavaScriptBody;
/**
* The {@code Float} class wraps a value of primitive type
* {@code float} in an object. An object of type
* {@code Float} contains a single field whose type is
* {@code float}.
*
* In addition, this class provides several methods for converting a
* {@code float} to a {@code String} and a
* {@code String} to a {@code float}, as well as other
* constants and methods useful when dealing with a
* {@code float}.
*
* @author Lee Boynton
* @author Arthur van Hoff
* @author Joseph D. Darcy
* @since JDK1.0
*/
public final class Float extends Number implements Comparable {
/**
* A constant holding the positive infinity of type
* {@code float}. It is equal to the value returned by
* {@code Float.intBitsToFloat(0x7f800000)}.
*/
public static final float POSITIVE_INFINITY = 1.0f / 0.0f;
/**
* A constant holding the negative infinity of type
* {@code float}. It is equal to the value returned by
* {@code Float.intBitsToFloat(0xff800000)}.
*/
public static final float NEGATIVE_INFINITY = -1.0f / 0.0f;
/**
* A constant holding a Not-a-Number (NaN) value of type
* {@code float}. It is equivalent to the value returned by
* {@code Float.intBitsToFloat(0x7fc00000)}.
*/
public static final float NaN = 0.0f / 0.0f;
/**
* A constant holding the largest positive finite value of type
* {@code float}, (2-2-23)·2127.
* It is equal to the hexadecimal floating-point literal
* {@code 0x1.fffffeP+127f} and also equal to
* {@code Float.intBitsToFloat(0x7f7fffff)}.
*/
public static final float MAX_VALUE = 0x1.fffffeP+127f; // 3.4028235e+38f
/**
* A constant holding the smallest positive normal value of type
* {@code float}, 2-126. It is equal to the
* hexadecimal floating-point literal {@code 0x1.0p-126f} and also
* equal to {@code Float.intBitsToFloat(0x00800000)}.
*
* @since 1.6
*/
public static final float MIN_NORMAL = 0x1.0p-126f; // 1.17549435E-38f
/**
* A constant holding the smallest positive nonzero value of type
* {@code float}, 2-149. It is equal to the
* hexadecimal floating-point literal {@code 0x0.000002P-126f}
* and also equal to {@code Float.intBitsToFloat(0x1)}.
*/
public static final float MIN_VALUE = 0x0.000002P-126f; // 1.4e-45f
/**
* Maximum exponent a finite {@code float} variable may have. It
* is equal to the value returned by {@code
* Math.getExponent(Float.MAX_VALUE)}.
*
* @since 1.6
*/
public static final int MAX_EXPONENT = 127;
/**
* Minimum exponent a normalized {@code float} variable may have.
* It is equal to the value returned by {@code
* Math.getExponent(Float.MIN_NORMAL)}.
*
* @since 1.6
*/
public static final int MIN_EXPONENT = -126;
/**
* The number of bits used to represent a {@code float} value.
*
* @since 1.5
*/
public static final int SIZE = 32;
/**
* The {@code Class} instance representing the primitive type
* {@code float}.
*
* @since JDK1.1
*/
public static final Class TYPE = Class.getPrimitiveClass("float");
/**
* Returns a string representation of the {@code float}
* argument. All characters mentioned below are ASCII characters.
*
* - If the argument is NaN, the result is the string
* "{@code NaN}".
*
- Otherwise, the result is a string that represents the sign and
* magnitude (absolute value) of the argument. If the sign is
* negative, the first character of the result is
* '{@code -}' (
'\u002D'); if the sign is
* positive, no sign character appears in the result. As for
* the magnitude m:
*
* - If m is infinity, it is represented by the characters
* {@code "Infinity"}; thus, positive infinity produces
* the result {@code "Infinity"} and negative infinity
* produces the result {@code "-Infinity"}.
*
- If m is zero, it is represented by the characters
* {@code "0.0"}; thus, negative zero produces the result
* {@code "-0.0"} and positive zero produces the result
* {@code "0.0"}.
*
- If m is greater than or equal to 10-3 but
* less than 107, then it is represented as the
* integer part of m, in decimal form with no leading
* zeroes, followed by '{@code .}'
* (
'\u002E'), followed by one or more
* decimal digits representing the fractional part of
* m.
* - If m is less than 10-3 or greater than or
* equal to 107, then it is represented in
* so-called "computerized scientific notation." Let n
* be the unique integer such that 10n ≤
* m {@literal <} 10n+1; then let a
* be the mathematically exact quotient of m and
* 10n so that 1 ≤ a {@literal <} 10.
* The magnitude is then represented as the integer part of
* a, as a single decimal digit, followed by
* '{@code .}' (
'\u002E'), followed by
* decimal digits representing the fractional part of
* a, followed by the letter '{@code E}'
* ('\u0045'), followed by a representation
* of n as a decimal integer, as produced by the
* method {@link java.lang.Integer#toString(int)}.
*
*
*
* How many digits must be printed for the fractional part of
* m or a? There must be at least one digit
* to represent the fractional part, and beyond that as many, but
* only as many, more digits as are needed to uniquely distinguish
* the argument value from adjacent values of type
* {@code float}. That is, suppose that x is the
* exact mathematical value represented by the decimal
* representation produced by this method for a finite nonzero
* argument f. Then f must be the {@code float}
* value nearest to x; or, if two {@code float} values are
* equally close to x, then f must be one of
* them and the least significant bit of the significand of
* f must be {@code 0}.
*
* To create localized string representations of a floating-point
* value, use subclasses of {@link java.text.NumberFormat}.
*
* @param f the float to be converted.
* @return a string representation of the argument.
*/
public static String toString(float f) {
return Double.toString(f);
}
/**
* Returns a hexadecimal string representation of the
* {@code float} argument. All characters mentioned below are
* ASCII characters.
*
*
* - If the argument is NaN, the result is the string
* "{@code NaN}".
*
- Otherwise, the result is a string that represents the sign and
* magnitude (absolute value) of the argument. If the sign is negative,
* the first character of the result is '{@code -}'
* (
'\u002D'); if the sign is positive, no sign character
* appears in the result. As for the magnitude m:
*
*
* - If m is infinity, it is represented by the string
* {@code "Infinity"}; thus, positive infinity produces the
* result {@code "Infinity"} and negative infinity produces
* the result {@code "-Infinity"}.
*
*
- If m is zero, it is represented by the string
* {@code "0x0.0p0"}; thus, negative zero produces the result
* {@code "-0x0.0p0"} and positive zero produces the result
* {@code "0x0.0p0"}.
*
*
- If m is a {@code float} value with a
* normalized representation, substrings are used to represent the
* significand and exponent fields. The significand is
* represented by the characters {@code "0x1."}
* followed by a lowercase hexadecimal representation of the rest
* of the significand as a fraction. Trailing zeros in the
* hexadecimal representation are removed unless all the digits
* are zero, in which case a single zero is used. Next, the
* exponent is represented by {@code "p"} followed
* by a decimal string of the unbiased exponent as if produced by
* a call to {@link Integer#toString(int) Integer.toString} on the
* exponent value.
*
*
- If m is a {@code float} value with a subnormal
* representation, the significand is represented by the
* characters {@code "0x0."} followed by a
* hexadecimal representation of the rest of the significand as a
* fraction. Trailing zeros in the hexadecimal representation are
* removed. Next, the exponent is represented by
* {@code "p-126"}. Note that there must be at
* least one nonzero digit in a subnormal significand.
*
*
*
*
*
*
* Examples
Floating-point Value Hexadecimal String
* {@code 1.0} {@code 0x1.0p0}
* {@code -1.0} {@code -0x1.0p0}
* {@code 2.0} {@code 0x1.0p1}
* {@code 3.0} {@code 0x1.8p1}
* {@code 0.5} {@code 0x1.0p-1}
* {@code 0.25} {@code 0x1.0p-2}
* {@code Float.MAX_VALUE}
* {@code 0x1.fffffep127}
* {@code Minimum Normal Value}
* {@code 0x1.0p-126}
* {@code Maximum Subnormal Value}
* {@code 0x0.fffffep-126}
* {@code Float.MIN_VALUE}
* {@code 0x0.000002p-126}
*
* @param f the {@code float} to be converted.
* @return a hex string representation of the argument.
* @since 1.5
* @author Joseph D. Darcy
*/
public static String toHexString(float f) {
throw new UnsupportedOperationException();
// if (Math.abs(f) < FloatConsts.MIN_NORMAL
// && f != 0.0f ) {// float subnormal
// // Adjust exponent to create subnormal double, then
// // replace subnormal double exponent with subnormal float
// // exponent
// String s = Double.toHexString(FpUtils.scalb((double)f,
// /* -1022+126 */
// DoubleConsts.MIN_EXPONENT-
// FloatConsts.MIN_EXPONENT));
// return s.replaceFirst("p-1022$", "p-126");
// }
// else // double string will be the same as float string
// return Double.toHexString(f);
}
/**
* Returns a {@code Float} object holding the
* {@code float} value represented by the argument string
* {@code s}.
*
* If {@code s} is {@code null}, then a
* {@code NullPointerException} is thrown.
*
*
Leading and trailing whitespace characters in {@code s}
* are ignored. Whitespace is removed as if by the {@link
* String#trim} method; that is, both ASCII space and control
* characters are removed. The rest of {@code s} should
* constitute a FloatValue as described by the lexical
* syntax rules:
*
*
*
* - FloatValue:
*
- Signopt {@code NaN}
*
- Signopt {@code Infinity}
*
- Signopt FloatingPointLiteral
*
- Signopt HexFloatingPointLiteral
*
- SignedInteger
*
*
*
*
*
* - HexFloatingPointLiteral:
*
- HexSignificand BinaryExponent FloatTypeSuffixopt
*
*
*
*
*
* - HexSignificand:
*
- HexNumeral
*
- HexNumeral {@code .}
*
- {@code 0x} HexDigitsopt
* {@code .} HexDigits
*
- {@code 0X} HexDigitsopt
* {@code .} HexDigits
*
*
*
*
*
* - BinaryExponent:
*
- BinaryExponentIndicator SignedInteger
*
*
*
*
*
* - BinaryExponentIndicator:
*
- {@code p}
*
- {@code P}
*
*
*
*
* where Sign, FloatingPointLiteral,
* HexNumeral, HexDigits, SignedInteger and
* FloatTypeSuffix are as defined in the lexical structure
* sections of
* The Java™ Language Specification,
* except that underscores are not accepted between digits.
* If {@code s} does not have the form of
* a FloatValue, then a {@code NumberFormatException}
* is thrown. Otherwise, {@code s} is regarded as
* representing an exact decimal value in the usual
* "computerized scientific notation" or as an exact
* hexadecimal value; this exact numerical value is then
* conceptually converted to an "infinitely precise"
* binary value that is then rounded to type {@code float}
* by the usual round-to-nearest rule of IEEE 754 floating-point
* arithmetic, which includes preserving the sign of a zero
* value.
*
* Note that the round-to-nearest rule also implies overflow and
* underflow behaviour; if the exact value of {@code s} is large
* enough in magnitude (greater than or equal to ({@link
* #MAX_VALUE} + {@link Math#ulp(float) ulp(MAX_VALUE)}/2),
* rounding to {@code float} will result in an infinity and if the
* exact value of {@code s} is small enough in magnitude (less
* than or equal to {@link #MIN_VALUE}/2), rounding to float will
* result in a zero.
*
* Finally, after rounding a {@code Float} object representing
* this {@code float} value is returned.
*
* To interpret localized string representations of a
* floating-point value, use subclasses of {@link
* java.text.NumberFormat}.
*
*
Note that trailing format specifiers, specifiers that
* determine the type of a floating-point literal
* ({@code 1.0f} is a {@code float} value;
* {@code 1.0d} is a {@code double} value), do
* not influence the results of this method. In other
* words, the numerical value of the input string is converted
* directly to the target floating-point type. In general, the
* two-step sequence of conversions, string to {@code double}
* followed by {@code double} to {@code float}, is
* not equivalent to converting a string directly to
* {@code float}. For example, if first converted to an
* intermediate {@code double} and then to
* {@code float}, the string
* {@code "1.00000017881393421514957253748434595763683319091796875001d"}
* results in the {@code float} value
* {@code 1.0000002f}; if the string is converted directly to
* {@code float}, 1.0000001f results.
*
*
To avoid calling this method on an invalid string and having
* a {@code NumberFormatException} be thrown, the documentation
* for {@link Double#valueOf Double.valueOf} lists a regular
* expression which can be used to screen the input.
*
* @param s the string to be parsed.
* @return a {@code Float} object holding the value
* represented by the {@code String} argument.
* @throws NumberFormatException if the string does not contain a
* parsable number.
*/
public static Float valueOf(String s) throws NumberFormatException {
return new Float(parseFloat(s));
}
/**
* Returns a {@code Float} instance representing the specified
* {@code float} value.
* If a new {@code Float} instance is not required, this method
* should generally be used in preference to the constructor
* {@link #Float(float)}, as this method is likely to yield
* significantly better space and time performance by caching
* frequently requested values.
*
* @param f a float value.
* @return a {@code Float} instance representing {@code f}.
* @since 1.5
*/
public static Float valueOf(float f) {
return new Float(f);
}
/**
* Returns a new {@code float} initialized to the value
* represented by the specified {@code String}, as performed
* by the {@code valueOf} method of class {@code Float}.
*
* @param s the string to be parsed.
* @return the {@code float} value represented by the string
* argument.
* @throws NullPointerException if the string is null
* @throws NumberFormatException if the string does not contain a
* parsable {@code float}.
* @see java.lang.Float#valueOf(String)
* @since 1.2
*/
@JavaScriptBody(args="s", body="return parseFloat(s);")
public static float parseFloat(String s) throws NumberFormatException {
return 0;
}
/**
* Returns {@code true} if the specified number is a
* Not-a-Number (NaN) value, {@code false} otherwise.
*
* @param v the value to be tested.
* @return {@code true} if the argument is NaN;
* {@code false} otherwise.
*/
static public boolean isNaN(float v) {
return (v != v);
}
/**
* Returns {@code true} if the specified number is infinitely
* large in magnitude, {@code false} otherwise.
*
* @param v the value to be tested.
* @return {@code true} if the argument is positive infinity or
* negative infinity; {@code false} otherwise.
*/
static public boolean isInfinite(float v) {
return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
}
/**
* The value of the Float.
*
* @serial
*/
private final float value;
/**
* Constructs a newly allocated {@code Float} object that
* represents the primitive {@code float} argument.
*
* @param value the value to be represented by the {@code Float}.
*/
public Float(float value) {
this.value = value;
}
/**
* Constructs a newly allocated {@code Float} object that
* represents the argument converted to type {@code float}.
*
* @param value the value to be represented by the {@code Float}.
*/
public Float(double value) {
this.value = (float)value;
}
/**
* Constructs a newly allocated {@code Float} object that
* represents the floating-point value of type {@code float}
* represented by the string. The string is converted to a
* {@code float} value as if by the {@code valueOf} method.
*
* @param s a string to be converted to a {@code Float}.
* @throws NumberFormatException if the string does not contain a
* parsable number.
* @see java.lang.Float#valueOf(java.lang.String)
*/
public Float(String s) throws NumberFormatException {
// REMIND: this is inefficient
this(valueOf(s).floatValue());
}
/**
* Returns {@code true} if this {@code Float} value is a
* Not-a-Number (NaN), {@code false} otherwise.
*
* @return {@code true} if the value represented by this object is
* NaN; {@code false} otherwise.
*/
public boolean isNaN() {
return isNaN(value);
}
/**
* Returns {@code true} if this {@code Float} value is
* infinitely large in magnitude, {@code false} otherwise.
*
* @return {@code true} if the value represented by this object is
* positive infinity or negative infinity;
* {@code false} otherwise.
*/
public boolean isInfinite() {
return isInfinite(value);
}
/**
* Returns a string representation of this {@code Float} object.
* The primitive {@code float} value represented by this object
* is converted to a {@code String} exactly as if by the method
* {@code toString} of one argument.
*
* @return a {@code String} representation of this object.
* @see java.lang.Float#toString(float)
*/
public String toString() {
return Float.toString(value);
}
/**
* Returns the value of this {@code Float} as a {@code byte} (by
* casting to a {@code byte}).
*
* @return the {@code float} value represented by this object
* converted to type {@code byte}
*/
public byte byteValue() {
return (byte)value;
}
/**
* Returns the value of this {@code Float} as a {@code short} (by
* casting to a {@code short}).
*
* @return the {@code float} value represented by this object
* converted to type {@code short}
* @since JDK1.1
*/
public short shortValue() {
return (short)value;
}
/**
* Returns the value of this {@code Float} as an {@code int} (by
* casting to type {@code int}).
*
* @return the {@code float} value represented by this object
* converted to type {@code int}
*/
public int intValue() {
return (int)value;
}
/**
* Returns value of this {@code Float} as a {@code long} (by
* casting to type {@code long}).
*
* @return the {@code float} value represented by this object
* converted to type {@code long}
*/
public long longValue() {
return (long)value;
}
/**
* Returns the {@code float} value of this {@code Float} object.
*
* @return the {@code float} value represented by this object
*/
public float floatValue() {
return value;
}
/**
* Returns the {@code double} value of this {@code Float} object.
*
* @return the {@code float} value represented by this
* object is converted to type {@code double} and the
* result of the conversion is returned.
*/
public double doubleValue() {
return (double)value;
}
/**
* Returns a hash code for this {@code Float} object. The
* result is the integer bit representation, exactly as produced
* by the method {@link #floatToIntBits(float)}, of the primitive
* {@code float} value represented by this {@code Float}
* object.
*
* @return a hash code value for this object.
*/
public int hashCode() {
return floatToIntBits(value);
}
/**
* Compares this object against the specified object. The result
* is {@code true} if and only if the argument is not
* {@code null} and is a {@code Float} object that
* represents a {@code float} with the same value as the
* {@code float} represented by this object. For this
* purpose, two {@code float} values are considered to be the
* same if and only if the method {@link #floatToIntBits(float)}
* returns the identical {@code int} value when applied to
* each.
*
*
Note that in most cases, for two instances of class
* {@code Float}, {@code f1} and {@code f2}, the value
* of {@code f1.equals(f2)} is {@code true} if and only if
*
*
* f1.floatValue() == f2.floatValue()
*
*
* also has the value {@code true}. However, there are two exceptions:
*
* - If {@code f1} and {@code f2} both represent
* {@code Float.NaN}, then the {@code equals} method returns
* {@code true}, even though {@code Float.NaN==Float.NaN}
* has the value {@code false}.
*
- If {@code f1} represents {@code +0.0f} while
* {@code f2} represents {@code -0.0f}, or vice
* versa, the {@code equal} test has the value
* {@code false}, even though {@code 0.0f==-0.0f}
* has the value {@code true}.
*
*
* This definition allows hash tables to operate properly.
*
* @param obj the object to be compared
* @return {@code true} if the objects are the same;
* {@code false} otherwise.
* @see java.lang.Float#floatToIntBits(float)
*/
public boolean equals(Object obj) {
return (obj instanceof Float)
&& (floatToIntBits(((Float)obj).value) == floatToIntBits(value));
}
/**
* Returns a representation of the specified floating-point value
* according to the IEEE 754 floating-point "single format" bit
* layout.
*
* Bit 31 (the bit that is selected by the mask
* {@code 0x80000000}) represents the sign of the floating-point
* number.
* Bits 30-23 (the bits that are selected by the mask
* {@code 0x7f800000}) represent the exponent.
* Bits 22-0 (the bits that are selected by the mask
* {@code 0x007fffff}) represent the significand (sometimes called
* the mantissa) of the floating-point number.
*
*
If the argument is positive infinity, the result is
* {@code 0x7f800000}.
*
*
If the argument is negative infinity, the result is
* {@code 0xff800000}.
*
*
If the argument is NaN, the result is {@code 0x7fc00000}.
*
*
In all cases, the result is an integer that, when given to the
* {@link #intBitsToFloat(int)} method, will produce a floating-point
* value the same as the argument to {@code floatToIntBits}
* (except all NaN values are collapsed to a single
* "canonical" NaN value).
*
* @param value a floating-point number.
* @return the bits that represent the floating-point number.
*/
public static int floatToIntBits(float value) {
final int EXP_BIT_MASK = 2139095040;
final int SIGNIF_BIT_MASK = 8388607;
int result = floatToRawIntBits(value);
// Check for NaN based on values of bit fields, maximum
// exponent and nonzero significand.
if ( ((result & EXP_BIT_MASK) ==
EXP_BIT_MASK) &&
(result & SIGNIF_BIT_MASK) != 0)
result = 0x7fc00000;
return result;
}
/**
* Returns a representation of the specified floating-point value
* according to the IEEE 754 floating-point "single format" bit
* layout, preserving Not-a-Number (NaN) values.
*
*
Bit 31 (the bit that is selected by the mask
* {@code 0x80000000}) represents the sign of the floating-point
* number.
* Bits 30-23 (the bits that are selected by the mask
* {@code 0x7f800000}) represent the exponent.
* Bits 22-0 (the bits that are selected by the mask
* {@code 0x007fffff}) represent the significand (sometimes called
* the mantissa) of the floating-point number.
*
*
If the argument is positive infinity, the result is
* {@code 0x7f800000}.
*
*
If the argument is negative infinity, the result is
* {@code 0xff800000}.
*
*
If the argument is NaN, the result is the integer representing
* the actual NaN value. Unlike the {@code floatToIntBits}
* method, {@code floatToRawIntBits} does not collapse all the
* bit patterns encoding a NaN to a single "canonical"
* NaN value.
*
*
In all cases, the result is an integer that, when given to the
* {@link #intBitsToFloat(int)} method, will produce a
* floating-point value the same as the argument to
* {@code floatToRawIntBits}.
*
* @param value a floating-point number.
* @return the bits that represent the floating-point number.
* @since 1.3
*/
@JavaScriptBody(args = { "value" }, body = ""
+ "var a = new ArrayBuffer(4);"
+ "new Float32Array(a)[0] = value;"
+ "return new Int32Array(a)[0];"
)
public static native int floatToRawIntBits(float value);
/**
* Returns the {@code float} value corresponding to a given
* bit representation.
* The argument is considered to be a representation of a
* floating-point value according to the IEEE 754 floating-point
* "single format" bit layout.
*
*
If the argument is {@code 0x7f800000}, the result is positive
* infinity.
*
*
If the argument is {@code 0xff800000}, the result is negative
* infinity.
*
*
If the argument is any value in the range
* {@code 0x7f800001} through {@code 0x7fffffff} or in
* the range {@code 0xff800001} through
* {@code 0xffffffff}, the result is a NaN. No IEEE 754
* floating-point operation provided by Java can distinguish
* between two NaN values of the same type with different bit
* patterns. Distinct values of NaN are only distinguishable by
* use of the {@code Float.floatToRawIntBits} method.
*
*
In all other cases, let s, e, and m be three
* values that can be computed from the argument:
*
*
* int s = ((bits >> 31) == 0) ? 1 : -1;
* int e = ((bits >> 23) & 0xff);
* int m = (e == 0) ?
* (bits & 0x7fffff) << 1 :
* (bits & 0x7fffff) | 0x800000;
*
*
* Then the floating-point result equals the value of the mathematical
* expression s·m·2e-150.
*
* Note that this method may not be able to return a
* {@code float} NaN with exactly same bit pattern as the
* {@code int} argument. IEEE 754 distinguishes between two
* kinds of NaNs, quiet NaNs and signaling NaNs. The
* differences between the two kinds of NaN are generally not
* visible in Java. Arithmetic operations on signaling NaNs turn
* them into quiet NaNs with a different, but often similar, bit
* pattern. However, on some processors merely copying a
* signaling NaN also performs that conversion. In particular,
* copying a signaling NaN to return it to the calling method may
* perform this conversion. So {@code intBitsToFloat} may
* not be able to return a {@code float} with a signaling NaN
* bit pattern. Consequently, for some {@code int} values,
* {@code floatToRawIntBits(intBitsToFloat(start))} may
* not equal {@code start}. Moreover, which
* particular bit patterns represent signaling NaNs is platform
* dependent; although all NaN bit patterns, quiet or signaling,
* must be in the NaN range identified above.
*
* @param bits an integer.
* @return the {@code float} floating-point value with the same bit
* pattern.
*/
@JavaScriptBody(args = "bits",
body =
"var s = ((bits >> 31) == 0) ? 1 : -1;\n"
+ "var e = ((bits >> 23) & 0xff);\n"
+ "if (e === 0xff) {\n"
+ " if ((bits & 0x7fffff) === 0) {\n"
+ " return (s > 0) ? Number.POSITIVE_INFINITY"
+ " : Number.NEGATIVE_INFINITY;\n"
+ " }\n"
+ " return Number.NaN;\n"
+ "}\n"
+ "var m = (e === 0) ?\n"
+ " (bits & 0x7fffff) << 1 :\n"
+ " (bits & 0x7fffff) | 0x800000;\n"
+ "return s * m * Math.pow(2.0, e - 150);\n"
)
public static native float intBitsToFloat(int bits);
/**
* Compares two {@code Float} objects numerically. There are
* two ways in which comparisons performed by this method differ
* from those performed by the Java language numerical comparison
* operators ({@code <, <=, ==, >=, >}) when
* applied to primitive {@code float} values:
*
*
-
* {@code Float.NaN} is considered by this method to
* be equal to itself and greater than all other
* {@code float} values
* (including {@code Float.POSITIVE_INFINITY}).
*
-
* {@code 0.0f} is considered by this method to be greater
* than {@code -0.0f}.
*
*
* This ensures that the natural ordering of {@code Float}
* objects imposed by this method is consistent with equals.
*
* @param anotherFloat the {@code Float} to be compared.
* @return the value {@code 0} if {@code anotherFloat} is
* numerically equal to this {@code Float}; a value
* less than {@code 0} if this {@code Float}
* is numerically less than {@code anotherFloat};
* and a value greater than {@code 0} if this
* {@code Float} is numerically greater than
* {@code anotherFloat}.
*
* @since 1.2
* @see Comparable#compareTo(Object)
*/
public int compareTo(Float anotherFloat) {
return Float.compare(value, anotherFloat.value);
}
/**
* Compares the two specified {@code float} values. The sign
* of the integer value returned is the same as that of the
* integer that would be returned by the call:
*
* new Float(f1).compareTo(new Float(f2))
*
*
* @param f1 the first {@code float} to compare.
* @param f2 the second {@code float} to compare.
* @return the value {@code 0} if {@code f1} is
* numerically equal to {@code f2}; a value less than
* {@code 0} if {@code f1} is numerically less than
* {@code f2}; and a value greater than {@code 0}
* if {@code f1} is numerically greater than
* {@code f2}.
* @since 1.4
*/
public static int compare(float f1, float f2) {
if (f1 < f2)
return -1; // Neither val is NaN, thisVal is smaller
if (f1 > f2)
return 1; // Neither val is NaN, thisVal is larger
// Cannot use floatToRawIntBits because of possibility of NaNs.
int thisBits = Float.floatToIntBits(f1);
int anotherBits = Float.floatToIntBits(f2);
return (thisBits == anotherBits ? 0 : // Values are equal
(thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
1)); // (0.0, -0.0) or (NaN, !NaN)
}
/** use serialVersionUID from JDK 1.0.2 for interoperability */
private static final long serialVersionUID = -2671257302660747028L;
}