| /* |
| * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved. |
| * 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 |
| * particular file as subject to the "Classpath" exception as provided |
| * 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 |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package java.lang; |
| |
| import sun.misc.FloatingDecimal; |
| import sun.misc.FpUtils; |
| import sun.misc.FloatConsts; |
| import sun.misc.DoubleConsts; |
| |
| /** |
| * 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}. |
| * |
| * <p>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<Float> { |
| /** |
| * 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<sup>-23</sup>)·2<sup>127</sup>. |
| * 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<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}, 2<sup>-149</sup>. 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<Float> TYPE = Class.getPrimitiveClass("float"); |
| |
| /** |
| * Returns a string representation of the {@code float} |
| * argument. All characters mentioned below are ASCII characters. |
| * <ul> |
| * <li>If the argument is NaN, the result is the string |
| * "{@code NaN}". |
| * <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>'\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"}; thus, positive infinity produces |
| * the result {@code "Infinity"} and negative infinity |
| * produces the result {@code "-Infinity"}. |
| * <li>If <i>m</i> 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"}. |
| * <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>'\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> {@literal <} 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> {@literal <} 10. |
| * The magnitude is then represented as the integer part of |
| * <i>a</i>, as a single decimal digit, followed by |
| * '{@code .}' (<code>'\u002E'</code>), followed by |
| * decimal digits representing the fractional part of |
| * <i>a</i>, followed by the letter '{@code E}' |
| * (<code>'\u0045'</code>), followed by a representation |
| * of <i>n</i> as a decimal integer, as produced by the |
| * method {@link java.lang.Integer#toString(int)}. |
| * |
| * </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}. 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} |
| * value nearest to <i>x</i>; or, if two {@code float} 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}. |
| * |
| * <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} argument. All characters mentioned below are |
| * ASCII characters. |
| * |
| * <ul> |
| * <li>If the argument is NaN, the result is the string |
| * "{@code NaN}". |
| * <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>'\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"}; thus, positive infinity produces the |
| * result {@code "Infinity"} and negative infinity produces |
| * the result {@code "-Infinity"}. |
| * |
| * <li>If <i>m</i> 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"}. |
| * |
| * <li>If <i>m</i> 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. |
| * |
| * <li>If <i>m</i> 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. |
| * |
| * </ul> |
| * |
| * </ul> |
| * |
| * <table border> |
| * <caption><h3>Examples</h3></caption> |
| * <tr><th>Floating-point Value</th><th>Hexadecimal String</th> |
| * <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td> |
| * <tr><td>{@code -1.0}</td> <td>{@code -0x1.0p0}</td> |
| * <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td> |
| * <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td> |
| * <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td> |
| * <tr><td>{@code 0.25}</td> <td>{@code 0x1.0p-2}</td> |
| * <tr><td>{@code Float.MAX_VALUE}</td> |
| * <td>{@code 0x1.fffffep127}</td> |
| * <tr><td>{@code Minimum Normal Value}</td> |
| * <td>{@code 0x1.0p-126}</td> |
| * <tr><td>{@code Maximum Subnormal Value}</td> |
| * <td>{@code 0x0.fffffep-126}</td> |
| * <tr><td>{@code Float.MIN_VALUE}</td> |
| * <td>{@code 0x0.000002p-126}</td> |
| * </table> |
| * @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) { |
| 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}. |
| * |
| * <p>If {@code s} is {@code null}, then a |
| * {@code NullPointerException} is thrown. |
| * |
| * <p>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 <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} |
| * <dd><i>Sign<sub>opt</sub></i> {@code Infinity} |
| * <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 .} |
| * <dd>{@code 0x} <i>HexDigits<sub>opt</sub> |
| * </i>{@code .}<i> HexDigits</i> |
| * <dd>{@code 0X}<i> HexDigits<sub>opt</sub> |
| * </i>{@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} |
| * <dd>{@code P} |
| * </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 |
| * <cite>The Java™ Language Specification</cite>, |
| * except that underscores are not accepted between digits. |
| * If {@code s} does not have the form of |
| * a <i>FloatValue</i>, 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. |
| * |
| * <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} is a {@code float} value; |
| * {@code 1.0d} is a {@code double} 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} |
| * followed by {@code double} to {@code float}, is |
| * <em>not</em> 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<br> |
| * {@code "1.00000017881393421514957253748434595763683319091796875001d"}<br> |
| * results in the {@code float} value |
| * {@code 1.0000002f}; if the string is converted directly to |
| * {@code float}, <code>1.000000<b>1</b>f</code> results. |
| * |
| * <p>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(FloatingDecimal.readJavaFormatString(s).floatValue()); |
| } |
| |
| /** |
| * 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 |
| */ |
| public static float parseFloat(String s) throws NumberFormatException { |
| return FloatingDecimal.readJavaFormatString(s).floatValue(); |
| } |
| |
| /** |
| * 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. |
| * |
| * <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> |
| * 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) |
| } |
| |
| /** use serialVersionUID from JDK 1.0.2 for interoperability */ |
| private static final long serialVersionUID = -2671257302660747028L; |
| } |
