/*
* @(#)Float.java 1.101 06/04/07
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.lang;
import sun.misc.FloatingDecimal;
import sun.misc.FpUtils;
import sun.misc.FloatConsts;
import sun.misc.DoubleConsts;
/**
* The <code>Float</code> class wraps a value of primitive type
* <code>float</code> in an object. An object of type
* <code>Float</code> contains a single field whose type is
* <code>float</code>.
* <p>
* In addition, this class provides several methods for converting a
* <code>float</code> to a <code>String</code> and a
* <code>String</code> to a <code>float</code>, as well as other
* constants and methods useful when dealing with a
* <code>float</code>.
*
* @author Lee Boynton
* @author Arthur van Hoff
* @author Joseph D. Darcy
* @version 1.101, 04/07/06
* @since JDK1.0
*/
public final class Float extends Number implements Comparable<Float> {
/**
* A constant holding the positive infinity of type
* <code>float</code>. It is equal to the value returned by
* <code>Float.intBitsToFloat(0x7f800000)</code>.
*/
public static final float POSITIVE_INFINITY = 1.0f / 0.0f;
/**
* A constant holding the negative infinity of type
* <code>float</code>. It is equal to the value returned by
* <code>Float.intBitsToFloat(0xff800000)</code>.
*/
public static final float NEGATIVE_INFINITY = -1.0f / 0.0f;
/**
* A constant holding a Not-a-Number (NaN) value of type
* <code>float</code>. It is equivalent to the value returned by
* <code>Float.intBitsToFloat(0x7fc00000)</code>.
*/
public static final float NaN = 0.0f / 0.0f;
/**
* A constant holding the largest positive finite value of type
* <code>float</code>, (2-2<sup>-23</sup>)·2<sup>127</sup>.
* It is equal to the hexadecimal floating-point literal
* <code>0x1.fffffeP+127f</code> and also equal to
* <code>Float.intBitsToFloat(0x7f7fffff)</code>.
*/
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<sup>-126</sup>. 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</code>, 2<sup>-149</sup>. It is equal to the
* hexadecimal floating-point literal <code>0x0.000002P-126f</code>
* and also equal to <code>Float.intBitsToFloat(0x1)</code>.
*/
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 <tt>float</tt> value.
*
* @since 1.5
*/
public static final int SIZE = 32;
/**
* The <code>Class</code> instance representing the primitive type
* <code>float</code>.
*
* @since JDK1.1
*/
public static final Class<Float> TYPE = Class.getPrimitiveClass("float");
/**
* Returns a string representation of the <code>float</code>
* argument. All characters mentioned below are ASCII characters.
* <ul>
* <li>If the argument is NaN, the result is the string
* "<code>NaN</code>".
* <li>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>-</code>' (<code>'\u002D'</code>); if the sign is
* positive, no sign character appears in the result. As for
* the magnitude <i>m</i>:
* <ul>
* <li>If <i>m</i> is infinity, it is represented by the characters
* <code>"Infinity"</code>; thus, positive infinity produces
* the result <code>"Infinity"</code> and negative infinity
* produces the result <code>"-Infinity"</code>.
* <li>If <i>m</i> is zero, it is represented by the characters
* <code>"0.0"</code>; thus, negative zero produces the result
* <code>"-0.0"</code> and positive zero produces the result
* <code>"0.0"</code>.
* <li> If <i>m</i> is greater than or equal to 10<sup>-3</sup> but
* less than 10<sup>7</sup>, then it is represented as the
* integer part of <i>m</i>, in decimal form with no leading
* zeroes, followed by '<code>.</code>'
* (<code>'\u002E'</code>), followed by one or more
* decimal digits representing the fractional part of
* <i>m</i>.
* <li> If <i>m</i> is less than 10<sup>-3</sup> or greater than or
* equal to 10<sup>7</sup>, then it is represented in
* so-called "computerized scientific notation." Let <i>n</i>
* be the unique integer such that 10<sup><i>n</i> </sup><=
* <i>m</i> < 10<sup><i>n</i>+1</sup>; then let <i>a</i>
* be the mathematically exact quotient of <i>m</i> and
* 10<sup><i>n</i></sup> so that 1 <= <i>a</i> < 10.
* The magnitude is then represented as the integer part of
* <i>a</i>, as a single decimal digit, followed by
* '<code>.</code>' (<code>'\u002E'</code>), followed by
* decimal digits representing the fractional part of
* <i>a</i>, followed by the letter '<code>E</code>'
* (<code>'\u0045'</code>), followed by a representation
* of <i>n</i> as a decimal integer, as produced by the
* method <code>{@link
* java.lang.Integer#toString(int)}</code>.
* </ul>
* </ul>
* How many digits must be printed for the fractional part of
* <i>m</i> or <i>a</i>? 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</code>. That is, suppose that <i>x</i> is the
* exact mathematical value represented by the decimal
* representation produced by this method for a finite nonzero
* argument <i>f</i>. Then <i>f</i> must be the <code>float</code>
* value nearest to <i>x</i>; or, if two <code>float</code> values are
* equally close to <i>x</i>, then <i>f</i> must be one of
* them and the least significant bit of the significand of
* <i>f</i> must be <code>0</code>.
* <p>
* 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 new FloatingDecimal(f).toJavaFormatString();
}
/**
* Returns a hexadecimal string representation of the
* <code>float</code> argument. All characters mentioned below are
* ASCII characters.
*
* <ul>
* <li>If the argument is NaN, the result is the string
* "<code>NaN</code>".
* <li>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>-</code>'
* (<code>'\u002D'</code>); if the sign is positive, no sign character
* appears in the result. As for the magnitude <i>m</i>:
*
* <ul>
* <li>If <i>m</i> is infinity, it is represented by the string
* <code>"Infinity"</code>; thus, positive infinity produces the
* result <code>"Infinity"</code> and negative infinity produces
* the result <code>"-Infinity"</code>.
*
* <li>If <i>m</i> is zero, it is represented by the string
* <code>"0x0.0p0"</code>; thus, negative zero produces the result
* <code>"-0x0.0p0"</code> and positive zero produces the result
* <code>"0x0.0p0"</code>.
*
* <li>If <i>m</i> is a <code>float</code> value with a
* normalized representation, substrings are used to represent the
* significand and exponent fields. The significand is
* represented by the characters <code>"0x1."</code>
* 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"</code> 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.
*
* <li>If <i>m</i> is a <code>float</code> value with a subnormal
* representation, the significand is represented by the
* characters <code>"0x0."</code> 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"</code>. Note that there must be at
* least one nonzero digit in a subnormal significand.
*
* </ul>
*
* </ul>
*
* <table border>
* <caption><h3>Examples</h3></caption>
* <tr><th>Floating-point Value</th><th>Hexadecimal String</th>
* <tr><td><code>1.0</code></td> <td><code>0x1.0p0</code></td>
* <tr><td><code>-1.0</code></td> <td><code>-0x1.0p0</code></td>
* <tr><td><code>2.0</code></td> <td><code>0x1.0p1</code></td>
* <tr><td><code>3.0</code></td> <td><code>0x1.8p1</code></td>
* <tr><td><code>0.5</code></td> <td><code>0x1.0p-1</code></td>
* <tr><td><code>0.25</code></td> <td><code>0x1.0p-2</code></td>
* <tr><td><code>Float.MAX_VALUE</code></td>
* <td><code>0x1.fffffep127</code></td>
* <tr><td><code>Minimum Normal Value</code></td>
* <td><code>0x1.0p-126</code></td>
* <tr><td><code>Maximum Subnormal Value</code></td>
* <td><code>0x0.fffffep-126</code></td>
* <tr><td><code>Float.MIN_VALUE</code></td>
* <td><code>0x0.000002p-126</code></td>
* </table>
* @param f the <code>float</code> to be converted.
* @return a hex string representation of the argument.
* @since 1.5
* @author Joseph D. Darcy
*/
public static String toHexString(float f) {
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</code> object holding the
* <code>float</code> value represented by the argument string
* <code>s</code>.
*
* <p>If <code>s</code> is <code>null</code>, then a
* <code>NullPointerException</code> is thrown.
*
* <p>Leading and trailing whitespace characters in <code>s</code>
* 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</code> should
* constitute a <i>FloatValue</i> as described by the lexical
* syntax rules:
*
* <blockquote>
* <dl>
* <dt><i>FloatValue:</i>
* <dd><i>Sign<sub>opt</sub></i> <code>NaN</code>
* <dd><i>Sign<sub>opt</sub></i> <code>Infinity</code>
* <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
* <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
* <dd><i>SignedInteger</i>
* </dl>
*
* <p>
*
* <dl>
* <dt><i>HexFloatingPointLiteral</i>:
* <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
* </dl>
*
* <p>
*
* <dl>
* <dt><i>HexSignificand:</i>
* <dd><i>HexNumeral</i>
* <dd><i>HexNumeral</i> <code>.</code>
* <dd><code>0x</code> <i>HexDigits<sub>opt</sub>
* </i><code>.</code><i> HexDigits</i>
* <dd><code>0X</code><i> HexDigits<sub>opt</sub>
* </i><code>.</code> <i>HexDigits</i>
* </dl>
*
* <p>
*
* <dl>
* <dt><i>BinaryExponent:</i>
* <dd><i>BinaryExponentIndicator SignedInteger</i>
* </dl>
*
* <p>
*
* <dl>
* <dt><i>BinaryExponentIndicator:</i>
* <dd><code>p</code>
* <dd><code>P</code>
* </dl>
*
* </blockquote>
*
* where <i>Sign</i>, <i>FloatingPointLiteral</i>,
* <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
* <i>FloatTypeSuffix</i> are as defined in the lexical structure
* sections of the of the <a
* href="http://java.sun.com/docs/books/jls/html/">Java Language
* Specification</a>. If <code>s</code> does not have the form of
* a <i>FloatValue</i>, then a <code>NumberFormatException</code>
* is thrown. Otherwise, <code>s</code> 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</code>
* by the usual round-to-nearest rule of IEEE 754 floating-point
* arithmetic, which includes preserving the sign of a zero
* value. Finally, a <code>Float</code> object representing this
* <code>float</code> value is returned.
*
* <p>To interpret localized string representations of a
* floating-point value, use subclasses of {@link
* java.text.NumberFormat}.
*
* <p>Note that trailing format specifiers, specifiers that
* determine the type of a floating-point literal
* (<code>1.0f</code> is a <code>float</code> value;
* <code>1.0d</code> is a <code>double</code> value), do
* <em>not</em> 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</code>
* followed by <code>double</code> to <code>float</code>, is
* <em>not</em> equivalent to converting a string directly to
* <code>float</code>. For example, if first converted to an
* intermediate <code>double</code> and then to
* <code>float</code>, the string<br>
* <code>"1.00000017881393421514957253748434595763683319091796875001d"</code><br>
* results in the <code>float</code> value
* <code>1.0000002f</code>; if the string is converted directly to
* <code>float</code>, <code>1.000000<b>1</b>f</code> results.
*
* <p>To avoid calling this method on an invalid string and having
* a <code>NumberFormatException</code> 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</code> object holding the value
* represented by the <code>String</code> argument.
* @exception NumberFormatException if the string does not contain a
* parsable number.
*/
public static Float valueOf(String s) throws NumberFormatException {
return new Float(FloatingDecimal.readJavaFormatString(s).floatValue());
}
/**
* Returns a <tt>Float</tt> instance representing the specified
* <tt>float</tt> value.
* If a new <tt>Float</tt> 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 <tt>Float</tt> instance representing <tt>f</tt>.
* @since 1.5
*/
public static Float valueOf(float f) {
return new Float(f);
}
/**
* Returns a new <code>float</code> initialized to the value
* represented by the specified <code>String</code>, as performed
* by the <code>valueOf</code> method of class <code>Float</code>.
*
* @param s the string to be parsed.
* @return the <code>float</code> value represented by the string
* argument.
* @exception NumberFormatException if the string does not contain a
* parsable <code>float</code>.
* @see java.lang.Float#valueOf(String)
* @since 1.2
*/
public static float parseFloat(String s) throws NumberFormatException {
return FloatingDecimal.readJavaFormatString(s).floatValue();
}
/**
* Returns <code>true</code> if the specified number is a
* Not-a-Number (NaN) value, <code>false</code> otherwise.
*
* @param v the value to be tested.
* @return <code>true</code> if the argument is NaN;
* <code>false</code> otherwise.
*/
static public boolean isNaN(float v) {
return (v != v);
}
/**
* Returns <code>true</code> if the specified number is infinitely
* large in magnitude, <code>false</code> otherwise.
*
* @param v the value to be tested.
* @return <code>true</code> if the argument is positive infinity or
* negative infinity; <code>false</code> 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</code> object that
* represents the primitive <code>float</code> argument.
*
* @param value the value to be represented by the <code>Float</code>.
*/
public Float(float value) {
this.value = value;
}
/**
* Constructs a newly allocated <code>Float</code> object that
* represents the argument converted to type <code>float</code>.
*
* @param value the value to be represented by the <code>Float</code>.
*/
public Float(double value) {
this.value = (float)value;
}
/**
* Constructs a newly allocated <code>Float</code> object that
* represents the floating-point value of type <code>float</code>
* represented by the string. The string is converted to a
* <code>float</code> value as if by the <code>valueOf</code> method.
*
* @param s a string to be converted to a <code>Float</code>.
* @exception 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</code> if this <code>Float</code> value is a
* Not-a-Number (NaN), <code>false</code> otherwise.
*
* @return <code>true</code> if the value represented by this object is
* NaN; <code>false</code> otherwise.
*/
public boolean isNaN() {
return isNaN(value);
}
/**
* Returns <code>true</code> if this <code>Float</code> value is
* infinitely large in magnitude, <code>false</code> otherwise.
*
* @return <code>true</code> if the value represented by this object is
* positive infinity or negative infinity;
* <code>false</code> otherwise.
*/
public boolean isInfinite() {
return isInfinite(value);
}
/**
* Returns a string representation of this <code>Float</code> object.
* The primitive <code>float</code> value represented by this object
* is converted to a <code>String</code> exactly as if by the method
* <code>toString</code> of one argument.
*
* @return a <code>String</code> representation of this object.
* @see java.lang.Float#toString(float)
*/
public String toString() {
return String.valueOf(value);
}
/**
* Returns the value of this <code>Float</code> as a
* <code>byte</code> (by casting to a <code>byte</code>).
*
* @return the <code>float</code> value represented by this object
* converted to type <code>byte</code>
*/
public byte byteValue() {
return (byte)value;
}
/**
* Returns the value of this <code>Float</code> as a
* <code>short</code> (by casting to a <code>short</code>).
*
* @return the <code>float</code> value represented by this object
* converted to type <code>short</code>
* @since JDK1.1
*/
public short shortValue() {
return (short)value;
}
/**
* Returns the value of this <code>Float</code> as an
* <code>int</code> (by casting to type <code>int</code>).
*
* @return the <code>float</code> value represented by this object
* converted to type <code>int</code>
*/
public int intValue() {
return (int)value;
}
/**
* Returns value of this <code>Float</code> as a <code>long</code>
* (by casting to type <code>long</code>).
*
* @return the <code>float</code> value represented by this object
* converted to type <code>long</code>
*/
public long longValue() {
return (long)value;
}
/**
* Returns the <code>float</code> value of this <code>Float</code>
* object.
*
* @return the <code>float</code> value represented by this object
*/
public float floatValue() {
return value;
}
/**
* Returns the <code>double</code> value of this
* <code>Float</code> object.
*
* @return the <code>float</code> value represented by this
* object is converted to type <code>double</code> and the
* result of the conversion is returned.
*/
public double doubleValue() {
return (double)value;
}
/**
* Returns a hash code for this <code>Float</code> object. The
* result is the integer bit representation, exactly as produced
* by the method {@link #floatToIntBits(float)}, of the primitive
* <code>float</code> value represented by this <code>Float</code>
* 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</code> if and only if the argument is not
* <code>null</code> and is a <code>Float</code> object that
* represents a <code>float</code> with the same value as the
* <code>float</code> represented by this object. For this
* purpose, two <code>float</code> values are considered to be the
* same if and only if the method {@link #floatToIntBits(float)}
* returns the identical <code>int</code> value when applied to
* each.
* <p>
* Note that in most cases, for two instances of class
* <code>Float</code>, <code>f1</code> and <code>f2</code>, the value
* of <code>f1.equals(f2)</code> is <code>true</code> if and only if
* <blockquote><pre>
* f1.floatValue() == f2.floatValue()
* </pre></blockquote>
* <p>
* also has the value <code>true</code>. However, there are two exceptions:
* <ul>
* <li>If <code>f1</code> and <code>f2</code> both represent
* <code>Float.NaN</code>, then the <code>equals</code> method returns
* <code>true</code>, even though <code>Float.NaN==Float.NaN</code>
* has the value <code>false</code>.
* <li>If <code>f1</code> represents <code>+0.0f</code> while
* <code>f2</code> represents <code>-0.0f</code>, or vice
* versa, the <code>equal</code> test has the value
* <code>false</code>, even though <code>0.0f==-0.0f</code>
* has the value <code>true</code>.
* </ul>
* This definition allows hash tables to operate properly.
*
* @param obj the object to be compared
* @return <code>true</code> if the objects are the same;
* <code>false</code> 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.
* <p>
* Bit 31 (the bit that is selected by the mask
* <code>0x80000000</code>) represents the sign of the floating-point
* number.
* Bits 30-23 (the bits that are selected by the mask
* <code>0x7f800000</code>) represent the exponent.
* Bits 22-0 (the bits that are selected by the mask
* <code>0x007fffff</code>) represent the significand (sometimes called
* the mantissa) of the floating-point number.
* <p>If the argument is positive infinity, the result is
* <code>0x7f800000</code>.
* <p>If the argument is negative infinity, the result is
* <code>0xff800000</code>.
* <p>If the argument is NaN, the result is <code>0x7fc00000</code>.
* <p>
* 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</code>
* (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) {
int result = floatToRawIntBits(value);
// Check for NaN based on values of bit fields, maximum
// exponent and nonzero significand.
if ( ((result & FloatConsts.EXP_BIT_MASK) ==
FloatConsts.EXP_BIT_MASK) &&
(result & FloatConsts.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.
* <p>
* Bit 31 (the bit that is selected by the mask
* <code>0x80000000</code>) represents the sign of the floating-point
* number.
* Bits 30-23 (the bits that are selected by the mask
* <code>0x7f800000</code>) represent the exponent.
* Bits 22-0 (the bits that are selected by the mask
* <code>0x007fffff</code>) represent the significand (sometimes called
* the mantissa) of the floating-point number.
* <p>If the argument is positive infinity, the result is
* <code>0x7f800000</code>.
* <p>If the argument is negative infinity, the result is
* <code>0xff800000</code>.
* <p>
* If the argument is NaN, the result is the integer representing
* the actual NaN value. Unlike the <code>floatToIntBits</code>
* method, <code>floatToRawIntBits</code> does not collapse all the
* bit patterns encoding a NaN to a single "canonical"
* NaN value.
* <p>
* 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</code>.
* @param value a floating-point number.
* @return the bits that represent the floating-point number.
* @since 1.3
*/
public static native int floatToRawIntBits(float value);
/**
* Returns the <code>float</code> 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.
* <p>
* If the argument is <code>0x7f800000</code>, the result is positive
* infinity.
* <p>
* If the argument is <code>0xff800000</code>, the result is negative
* infinity.
* <p>
* If the argument is any value in the range
* <code>0x7f800001</code> through <code>0x7fffffff</code> or in
* the range <code>0xff800001</code> through
* <code>0xffffffff</code>, 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</code> method.
* <p>
* In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
* values that can be computed from the argument:
* <blockquote><pre>
* int s = ((bits >> 31) == 0) ? 1 : -1;
* int e = ((bits >> 23) & 0xff);
* int m = (e == 0) ?
* (bits & 0x7fffff) << 1 :
* (bits & 0x7fffff) | 0x800000;
* </pre></blockquote>
* Then the floating-point result equals the value of the mathematical
* expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-150</sup>.
*<p>
* Note that this method may not be able to return a
* <code>float</code> NaN with exactly same bit pattern as the
* <code>int</code> argument. IEEE 754 distinguishes between two
* kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. 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</code> may
* not be able to return a <code>float</code> with a signaling NaN
* bit pattern. Consequently, for some <code>int</code> values,
* <code>floatToRawIntBits(intBitsToFloat(start))</code> may
* <i>not</i> equal <code>start</code>. 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</code> floating-point value with the same bit
* pattern.
*/
public static native float intBitsToFloat(int bits);
/**
* Compares two <code>Float</code> 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><, <=, ==, >= ></code>) when
* applied to primitive <code>float</code> values:
* <ul><li>
* <code>Float.NaN</code> is considered by this method to
* be equal to itself and greater than all other
* <code>float</code> values
* (including <code>Float.POSITIVE_INFINITY</code>).
* <li>
* <code>0.0f</code> is considered by this method to be greater
* than <code>-0.0f</code>.
* </ul>
* This ensures that the <i>natural ordering</i> of <tt>Float</tt>
* objects imposed by this method is <i>consistent with equals</i>.
*
* @param anotherFloat the <code>Float</code> to be compared.
* @return the value <code>0</code> if <code>anotherFloat</code> is
* numerically equal to this <code>Float</code>; a value
* less than <code>0</code> if this <code>Float</code>
* is numerically less than <code>anotherFloat</code>;
* and a value greater than <code>0</code> if this
* <code>Float</code> is numerically greater than
* <code>anotherFloat</code>.
*
* @since 1.2
* @see Comparable#compareTo(Object)
*/
public int compareTo(Float anotherFloat) {
return Float.compare(value, anotherFloat.value);
}
/**
* Compares the two specified <code>float</code> values. The sign
* of the integer value returned is the same as that of the
* integer that would be returned by the call:
* <pre>
* new Float(f1).compareTo(new Float(f2))
* </pre>
*
* @param f1 the first <code>float</code> to compare.
* @param f2 the second <code>float</code> to compare.
* @return the value <code>0</code> if <code>f1</code> is
* numerically equal to <code>f2</code>; a value less than
* <code>0</code> if <code>f1</code> is numerically less than
* <code>f2</code>; and a value greater than <code>0</code>
* if <code>f1</code> is numerically greater than
* <code>f2</code>.
* @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
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;
}
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