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966 lines
36 KiB
966 lines
36 KiB
/*
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* Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*/
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package java.lang;
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import sun.misc.FloatingDecimal;
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import sun.misc.FloatConsts;
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import sun.misc.DoubleConsts;
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/**
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* The {@code Float} class wraps a value of primitive type
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* {@code float} in an object. An object of type
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* {@code Float} contains a single field whose type is
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* {@code float}.
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*
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* <p>In addition, this class provides several methods for converting a
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* {@code float} to a {@code String} and a
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* {@code String} to a {@code float}, as well as other
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* constants and methods useful when dealing with a
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* {@code float}.
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*
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* @author Lee Boynton
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* @author Arthur van Hoff
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* @author Joseph D. Darcy
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* @since JDK1.0
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*/
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public final class Float extends Number implements Comparable<Float> {
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/**
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* A constant holding the positive infinity of type
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* {@code float}. It is equal to the value returned by
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* {@code Float.intBitsToFloat(0x7f800000)}.
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*/
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public static final float POSITIVE_INFINITY = 1.0f / 0.0f;
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/**
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* A constant holding the negative infinity of type
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* {@code float}. It is equal to the value returned by
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* {@code Float.intBitsToFloat(0xff800000)}.
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*/
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public static final float NEGATIVE_INFINITY = -1.0f / 0.0f;
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/**
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* A constant holding a Not-a-Number (NaN) value of type
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* {@code float}. It is equivalent to the value returned by
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* {@code Float.intBitsToFloat(0x7fc00000)}.
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*/
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public static final float NaN = 0.0f / 0.0f;
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/**
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* A constant holding the largest positive finite value of type
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* {@code float}, (2-2<sup>-23</sup>)·2<sup>127</sup>.
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* It is equal to the hexadecimal floating-point literal
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* {@code 0x1.fffffeP+127f} and also equal to
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* {@code Float.intBitsToFloat(0x7f7fffff)}.
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*/
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public static final float MAX_VALUE = 0x1.fffffeP+127f; // 3.4028235e+38f
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/**
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* A constant holding the smallest positive normal value of type
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* {@code float}, 2<sup>-126</sup>. It is equal to the
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* hexadecimal floating-point literal {@code 0x1.0p-126f} and also
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* equal to {@code Float.intBitsToFloat(0x00800000)}.
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*
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* @since 1.6
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*/
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public static final float MIN_NORMAL = 0x1.0p-126f; // 1.17549435E-38f
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/**
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* A constant holding the smallest positive nonzero value of type
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* {@code float}, 2<sup>-149</sup>. It is equal to the
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* hexadecimal floating-point literal {@code 0x0.000002P-126f}
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* and also equal to {@code Float.intBitsToFloat(0x1)}.
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*/
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public static final float MIN_VALUE = 0x0.000002P-126f; // 1.4e-45f
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/**
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* Maximum exponent a finite {@code float} variable may have. It
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* is equal to the value returned by {@code
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* Math.getExponent(Float.MAX_VALUE)}.
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*
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* @since 1.6
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*/
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public static final int MAX_EXPONENT = 127;
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/**
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* Minimum exponent a normalized {@code float} variable may have.
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* It is equal to the value returned by {@code
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* Math.getExponent(Float.MIN_NORMAL)}.
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*
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* @since 1.6
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*/
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public static final int MIN_EXPONENT = -126;
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/**
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* The number of bits used to represent a {@code float} value.
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*
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* @since 1.5
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*/
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public static final int SIZE = 32;
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/**
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* The number of bytes used to represent a {@code float} value.
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*
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* @since 1.8
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*/
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public static final int BYTES = SIZE / Byte.SIZE;
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/**
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* The {@code Class} instance representing the primitive type
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* {@code float}.
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*
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* @since JDK1.1
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*/
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@SuppressWarnings("unchecked")
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public static final Class<Float> TYPE = (Class<Float>) Class.getPrimitiveClass("float");
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/**
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* Returns a string representation of the {@code float}
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* argument. All characters mentioned below are ASCII characters.
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* <ul>
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* <li>If the argument is NaN, the result is the string
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* "{@code NaN}".
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* <li>Otherwise, the result is a string that represents the sign and
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* magnitude (absolute value) of the argument. If the sign is
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* negative, the first character of the result is
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* '{@code -}' ({@code '\u005Cu002D'}); if the sign is
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* positive, no sign character appears in the result. As for
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* the magnitude <i>m</i>:
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* <ul>
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* <li>If <i>m</i> is infinity, it is represented by the characters
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* {@code "Infinity"}; thus, positive infinity produces
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* the result {@code "Infinity"} and negative infinity
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* produces the result {@code "-Infinity"}.
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* <li>If <i>m</i> is zero, it is represented by the characters
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* {@code "0.0"}; thus, negative zero produces the result
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* {@code "-0.0"} and positive zero produces the result
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* {@code "0.0"}.
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* <li> If <i>m</i> is greater than or equal to 10<sup>-3</sup> but
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* less than 10<sup>7</sup>, then it is represented as the
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* integer part of <i>m</i>, in decimal form with no leading
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* zeroes, followed by '{@code .}'
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* ({@code '\u005Cu002E'}), followed by one or more
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* decimal digits representing the fractional part of
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* <i>m</i>.
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* <li> If <i>m</i> is less than 10<sup>-3</sup> or greater than or
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* equal to 10<sup>7</sup>, then it is represented in
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* so-called "computerized scientific notation." Let <i>n</i>
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* be the unique integer such that 10<sup><i>n</i> </sup>≤
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* <i>m</i> {@literal <} 10<sup><i>n</i>+1</sup>; then let <i>a</i>
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* be the mathematically exact quotient of <i>m</i> and
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* 10<sup><i>n</i></sup> so that 1 ≤ <i>a</i> {@literal <} 10.
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* The magnitude is then represented as the integer part of
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* <i>a</i>, as a single decimal digit, followed by
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* '{@code .}' ({@code '\u005Cu002E'}), followed by
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* decimal digits representing the fractional part of
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* <i>a</i>, followed by the letter '{@code E}'
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* ({@code '\u005Cu0045'}), followed by a representation
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* of <i>n</i> as a decimal integer, as produced by the
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* method {@link java.lang.Integer#toString(int)}.
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*
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* </ul>
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* </ul>
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* How many digits must be printed for the fractional part of
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* <i>m</i> or <i>a</i>? There must be at least one digit
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* to represent the fractional part, and beyond that as many, but
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* only as many, more digits as are needed to uniquely distinguish
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* the argument value from adjacent values of type
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* {@code float}. That is, suppose that <i>x</i> is the
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* exact mathematical value represented by the decimal
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* representation produced by this method for a finite nonzero
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* argument <i>f</i>. Then <i>f</i> must be the {@code float}
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* value nearest to <i>x</i>; or, if two {@code float} values are
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* equally close to <i>x</i>, then <i>f</i> must be one of
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* them and the least significant bit of the significand of
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* <i>f</i> must be {@code 0}.
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*
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* <p>To create localized string representations of a floating-point
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* value, use subclasses of {@link java.text.NumberFormat}.
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*
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* @param f the float to be converted.
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* @return a string representation of the argument.
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*/
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public static String toString(float f) {
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return FloatingDecimal.toJavaFormatString(f);
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}
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/**
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* Returns a hexadecimal string representation of the
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* {@code float} argument. All characters mentioned below are
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* ASCII characters.
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*
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* <ul>
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* <li>If the argument is NaN, the result is the string
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* "{@code NaN}".
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* <li>Otherwise, the result is a string that represents the sign and
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* magnitude (absolute value) of the argument. If the sign is negative,
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* the first character of the result is '{@code -}'
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* ({@code '\u005Cu002D'}); if the sign is positive, no sign character
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* appears in the result. As for the magnitude <i>m</i>:
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*
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* <ul>
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* <li>If <i>m</i> is infinity, it is represented by the string
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* {@code "Infinity"}; thus, positive infinity produces the
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* result {@code "Infinity"} and negative infinity produces
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* the result {@code "-Infinity"}.
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*
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* <li>If <i>m</i> is zero, it is represented by the string
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* {@code "0x0.0p0"}; thus, negative zero produces the result
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* {@code "-0x0.0p0"} and positive zero produces the result
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* {@code "0x0.0p0"}.
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*
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* <li>If <i>m</i> is a {@code float} value with a
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* normalized representation, substrings are used to represent the
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* significand and exponent fields. The significand is
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* represented by the characters {@code "0x1."}
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* followed by a lowercase hexadecimal representation of the rest
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* of the significand as a fraction. Trailing zeros in the
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* hexadecimal representation are removed unless all the digits
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* are zero, in which case a single zero is used. Next, the
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* exponent is represented by {@code "p"} followed
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* by a decimal string of the unbiased exponent as if produced by
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* a call to {@link Integer#toString(int) Integer.toString} on the
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* exponent value.
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*
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* <li>If <i>m</i> is a {@code float} value with a subnormal
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* representation, the significand is represented by the
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* characters {@code "0x0."} followed by a
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* hexadecimal representation of the rest of the significand as a
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* fraction. Trailing zeros in the hexadecimal representation are
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* removed. Next, the exponent is represented by
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* {@code "p-126"}. Note that there must be at
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* least one nonzero digit in a subnormal significand.
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*
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* </ul>
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*
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* </ul>
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*
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* <table border>
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* <caption>Examples</caption>
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* <tr><th>Floating-point Value</th><th>Hexadecimal String</th>
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* <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td>
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* <tr><td>{@code -1.0}</td> <td>{@code -0x1.0p0}</td>
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* <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td>
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* <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td>
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* <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td>
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* <tr><td>{@code 0.25}</td> <td>{@code 0x1.0p-2}</td>
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* <tr><td>{@code Float.MAX_VALUE}</td>
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* <td>{@code 0x1.fffffep127}</td>
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* <tr><td>{@code Minimum Normal Value}</td>
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* <td>{@code 0x1.0p-126}</td>
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* <tr><td>{@code Maximum Subnormal Value}</td>
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* <td>{@code 0x0.fffffep-126}</td>
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* <tr><td>{@code Float.MIN_VALUE}</td>
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* <td>{@code 0x0.000002p-126}</td>
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* </table>
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* @param f the {@code float} to be converted.
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* @return a hex string representation of the argument.
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* @since 1.5
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* @author Joseph D. Darcy
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*/
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public static String toHexString(float f) {
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if (Math.abs(f) < FloatConsts.MIN_NORMAL
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&& f != 0.0f ) {// float subnormal
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// Adjust exponent to create subnormal double, then
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// replace subnormal double exponent with subnormal float
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// exponent
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String s = Double.toHexString(Math.scalb((double)f,
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/* -1022+126 */
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DoubleConsts.MIN_EXPONENT-
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FloatConsts.MIN_EXPONENT));
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return s.replaceFirst("p-1022$", "p-126");
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}
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else // double string will be the same as float string
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return Double.toHexString(f);
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}
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/**
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* Returns a {@code Float} object holding the
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* {@code float} value represented by the argument string
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* {@code s}.
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*
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* <p>If {@code s} is {@code null}, then a
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* {@code NullPointerException} is thrown.
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*
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* <p>Leading and trailing whitespace characters in {@code s}
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* are ignored. Whitespace is removed as if by the {@link
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* String#trim} method; that is, both ASCII space and control
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* characters are removed. The rest of {@code s} should
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* constitute a <i>FloatValue</i> as described by the lexical
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* syntax rules:
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*
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* <blockquote>
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* <dl>
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* <dt><i>FloatValue:</i>
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* <dd><i>Sign<sub>opt</sub></i> {@code NaN}
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* <dd><i>Sign<sub>opt</sub></i> {@code Infinity}
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* <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
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* <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
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* <dd><i>SignedInteger</i>
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* </dl>
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*
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* <dl>
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* <dt><i>HexFloatingPointLiteral</i>:
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* <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
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* </dl>
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*
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* <dl>
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* <dt><i>HexSignificand:</i>
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* <dd><i>HexNumeral</i>
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* <dd><i>HexNumeral</i> {@code .}
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* <dd>{@code 0x} <i>HexDigits<sub>opt</sub>
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* </i>{@code .}<i> HexDigits</i>
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* <dd>{@code 0X}<i> HexDigits<sub>opt</sub>
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* </i>{@code .} <i>HexDigits</i>
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* </dl>
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*
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* <dl>
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* <dt><i>BinaryExponent:</i>
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* <dd><i>BinaryExponentIndicator SignedInteger</i>
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* </dl>
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*
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* <dl>
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* <dt><i>BinaryExponentIndicator:</i>
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* <dd>{@code p}
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* <dd>{@code P}
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* </dl>
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*
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* </blockquote>
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*
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* where <i>Sign</i>, <i>FloatingPointLiteral</i>,
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* <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
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* <i>FloatTypeSuffix</i> are as defined in the lexical structure
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* sections of
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* <cite>The Java™ Language Specification</cite>,
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* except that underscores are not accepted between digits.
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* If {@code s} does not have the form of
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* a <i>FloatValue</i>, then a {@code NumberFormatException}
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* is thrown. Otherwise, {@code s} is regarded as
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* representing an exact decimal value in the usual
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* "computerized scientific notation" or as an exact
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* hexadecimal value; this exact numerical value is then
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* conceptually converted to an "infinitely precise"
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* binary value that is then rounded to type {@code float}
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* by the usual round-to-nearest rule of IEEE 754 floating-point
|
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* arithmetic, which includes preserving the sign of a zero
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* value.
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*
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* Note that the round-to-nearest rule also implies overflow and
|
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* underflow behaviour; if the exact value of {@code s} is large
|
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* enough in magnitude (greater than or equal to ({@link
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* #MAX_VALUE} + {@link Math#ulp(float) ulp(MAX_VALUE)}/2),
|
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* rounding to {@code float} will result in an infinity and if the
|
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* exact value of {@code s} is small enough in magnitude (less
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* than or equal to {@link #MIN_VALUE}/2), rounding to float will
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* result in a zero.
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*
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* Finally, after rounding a {@code Float} object representing
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* this {@code float} value is returned.
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*
|
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* <p>To interpret localized string representations of a
|
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* floating-point value, use subclasses of {@link
|
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* java.text.NumberFormat}.
|
|
*
|
|
* <p>Note that trailing format specifiers, specifiers that
|
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* determine the type of a floating-point literal
|
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* ({@code 1.0f} is a {@code float} value;
|
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* {@code 1.0d} is a {@code double} value), do
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* <em>not</em> influence the results of this method. In other
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* words, the numerical value of the input string is converted
|
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* directly to the target floating-point type. In general, the
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* two-step sequence of conversions, string to {@code double}
|
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* followed by {@code double} to {@code float}, is
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* <em>not</em> equivalent to converting a string directly to
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* {@code float}. For example, if first converted to an
|
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* intermediate {@code double} and then to
|
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* {@code float}, the string<br>
|
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* {@code "1.00000017881393421514957253748434595763683319091796875001d"}<br>
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* results in the {@code float} value
|
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* {@code 1.0000002f}; if the string is converted directly to
|
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* {@code float}, <code>1.000000<b>1</b>f</code> results.
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*
|
|
* <p>To avoid calling this method on an invalid string and having
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* a {@code NumberFormatException} be thrown, the documentation
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* for {@link Double#valueOf Double.valueOf} lists a regular
|
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* expression which can be used to screen the input.
|
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*
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* @param s the string to be parsed.
|
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* @return a {@code Float} object holding the value
|
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* represented by the {@code String} argument.
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* @throws NumberFormatException if the string does not contain a
|
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* parsable number.
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*/
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public static Float valueOf(String s) throws NumberFormatException {
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return new Float(parseFloat(s));
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}
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|
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/**
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* Returns a {@code Float} instance representing the specified
|
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* {@code float} value.
|
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* 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
|
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* frequently requested values.
|
|
*
|
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* @param f a float value.
|
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* @return a {@code Float} instance representing {@code f}.
|
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* @since 1.5
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*/
|
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public static Float valueOf(float f) {
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return new Float(f);
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}
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|
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/**
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* Returns a new {@code float} initialized to the value
|
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* represented by the specified {@code String}, as performed
|
|
* by the {@code valueOf} method of class {@code Float}.
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*
|
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* @param s the string to be parsed.
|
|
* @return the {@code float} value represented by the string
|
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* argument.
|
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* @throws NullPointerException if the string is null
|
|
* @throws NumberFormatException if the string does not contain a
|
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* parsable {@code float}.
|
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* @see java.lang.Float#valueOf(String)
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* @since 1.2
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*/
|
|
public static float parseFloat(String s) throws NumberFormatException {
|
|
return FloatingDecimal.parseFloat(s);
|
|
}
|
|
|
|
/**
|
|
* 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.
|
|
*/
|
|
public static 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.
|
|
*/
|
|
public static boolean isInfinite(float v) {
|
|
return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
|
|
}
|
|
|
|
|
|
/**
|
|
* Returns {@code true} if the argument is a finite floating-point
|
|
* value; returns {@code false} otherwise (for NaN and infinity
|
|
* arguments).
|
|
*
|
|
* @param f the {@code float} value to be tested
|
|
* @return {@code true} if the argument is a finite
|
|
* floating-point value, {@code false} otherwise.
|
|
* @since 1.8
|
|
*/
|
|
public static boolean isFinite(float f) {
|
|
return Math.abs(f) <= FloatConsts.MAX_VALUE;
|
|
}
|
|
|
|
/**
|
|
* 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 {
|
|
value = parseFloat(s);
|
|
}
|
|
|
|
/**
|
|
* 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} after
|
|
* a narrowing primitive conversion.
|
|
*
|
|
* @return the {@code float} value represented by this object
|
|
* converted to type {@code byte}
|
|
* @jls 5.1.3 Narrowing Primitive Conversions
|
|
*/
|
|
public byte byteValue() {
|
|
return (byte)value;
|
|
}
|
|
|
|
/**
|
|
* Returns the value of this {@code Float} as a {@code short}
|
|
* after a narrowing primitive conversion.
|
|
*
|
|
* @return the {@code float} value represented by this object
|
|
* converted to type {@code short}
|
|
* @jls 5.1.3 Narrowing Primitive Conversions
|
|
* @since JDK1.1
|
|
*/
|
|
public short shortValue() {
|
|
return (short)value;
|
|
}
|
|
|
|
/**
|
|
* Returns the value of this {@code Float} as an {@code int} after
|
|
* a narrowing primitive conversion.
|
|
*
|
|
* @return the {@code float} value represented by this object
|
|
* converted to type {@code int}
|
|
* @jls 5.1.3 Narrowing Primitive Conversions
|
|
*/
|
|
public int intValue() {
|
|
return (int)value;
|
|
}
|
|
|
|
/**
|
|
* Returns value of this {@code Float} as a {@code long} after a
|
|
* narrowing primitive conversion.
|
|
*
|
|
* @return the {@code float} value represented by this object
|
|
* converted to type {@code long}
|
|
* @jls 5.1.3 Narrowing Primitive Conversions
|
|
*/
|
|
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 value of this {@code Float} as a {@code double}
|
|
* after a widening primitive conversion.
|
|
*
|
|
* @return the {@code float} value represented by this
|
|
* object converted to type {@code double}
|
|
* @jls 5.1.2 Widening Primitive Conversions
|
|
*/
|
|
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.
|
|
*/
|
|
@Override
|
|
public int hashCode() {
|
|
return Float.hashCode(value);
|
|
}
|
|
|
|
/**
|
|
* Returns a hash code for a {@code float} value; compatible with
|
|
* {@code Float.hashCode()}.
|
|
*
|
|
* @param value the value to hash
|
|
* @return a hash code value for a {@code float} value.
|
|
* @since 1.8
|
|
*/
|
|
public static int hashCode(float value) {
|
|
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.
|
|
*
|
|
* <p>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
|
|
*
|
|
* <blockquote><pre>
|
|
* f1.floatValue() == f2.floatValue()
|
|
* </pre></blockquote>
|
|
*
|
|
* <p>also has the value {@code true}. However, there are two exceptions:
|
|
* <ul>
|
|
* <li>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}.
|
|
* <li>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}.
|
|
* </ul>
|
|
*
|
|
* 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.
|
|
*
|
|
* <p>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.
|
|
*
|
|
* <p>If the argument is positive infinity, the result is
|
|
* {@code 0x7f800000}.
|
|
*
|
|
* <p>If the argument is negative infinity, the result is
|
|
* {@code 0xff800000}.
|
|
*
|
|
* <p>If the argument is NaN, the result is {@code 0x7fc00000}.
|
|
*
|
|
* <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}
|
|
* (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}) 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.
|
|
*
|
|
* <p>If the argument is positive infinity, the result is
|
|
* {@code 0x7f800000}.
|
|
*
|
|
* <p>If the argument is negative infinity, the result is
|
|
* {@code 0xff800000}.
|
|
*
|
|
* <p>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.
|
|
*
|
|
* <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}.
|
|
*
|
|
* @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} 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}, the result is positive
|
|
* infinity.
|
|
*
|
|
* <p>If the argument is {@code 0xff800000}, the result is negative
|
|
* infinity.
|
|
*
|
|
* <p>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.
|
|
*
|
|
* <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>{@code
|
|
* 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} NaN with exactly same bit pattern as the
|
|
* {@code int} 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} 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
|
|
* <i>not</i> 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.
|
|
*/
|
|
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:
|
|
*
|
|
* <ul><li>
|
|
* {@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}).
|
|
* <li>
|
|
* {@code 0.0f} is considered by this method to be greater
|
|
* than {@code -0.0f}.
|
|
* </ul>
|
|
*
|
|
* This ensures that the <i>natural ordering</i> of {@code Float}
|
|
* objects imposed by this method is <i>consistent with equals</i>.
|
|
*
|
|
* @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:
|
|
* <pre>
|
|
* new Float(f1).compareTo(new Float(f2))
|
|
* </pre>
|
|
*
|
|
* @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)
|
|
}
|
|
|
|
/**
|
|
* Adds two {@code float} values together as per the + operator.
|
|
*
|
|
* @param a the first operand
|
|
* @param b the second operand
|
|
* @return the sum of {@code a} and {@code b}
|
|
* @jls 4.2.4 Floating-Point Operations
|
|
* @see java.util.function.BinaryOperator
|
|
* @since 1.8
|
|
*/
|
|
public static float sum(float a, float b) {
|
|
return a + b;
|
|
}
|
|
|
|
/**
|
|
* Returns the greater of two {@code float} values
|
|
* as if by calling {@link Math#max(float, float) Math.max}.
|
|
*
|
|
* @param a the first operand
|
|
* @param b the second operand
|
|
* @return the greater of {@code a} and {@code b}
|
|
* @see java.util.function.BinaryOperator
|
|
* @since 1.8
|
|
*/
|
|
public static float max(float a, float b) {
|
|
return Math.max(a, b);
|
|
}
|
|
|
|
/**
|
|
* Returns the smaller of two {@code float} values
|
|
* as if by calling {@link Math#min(float, float) Math.min}.
|
|
*
|
|
* @param a the first operand
|
|
* @param b the second operand
|
|
* @return the smaller of {@code a} and {@code b}
|
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* @see java.util.function.BinaryOperator
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* @since 1.8
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*/
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public static float min(float a, float b) {
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return Math.min(a, b);
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}
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/** use serialVersionUID from JDK 1.0.2 for interoperability */
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private static final long serialVersionUID = -2671257302660747028L;
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}
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