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| 1 | /* | ||
| 2 | * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package java.lang; | ||
| 27 | |||
| 28 | import sun.misc.FloatingDecimal; | ||
| 29 | import sun.misc.FpUtils; | ||
| 30 | import sun.misc.DoubleConsts; | ||
| 31 | |||
| 32 | /** | ||
| 33 | * The {@code Double} class wraps a value of the primitive type | ||
| 34 | * {@code double} in an object. An object of type | ||
| 35 | * {@code Double} contains a single field whose type is | ||
| 36 | * {@code double}. | ||
| 37 | * | ||
| 38 | * <p>In addition, this class provides several methods for converting a | ||
| 39 | * {@code double} to a {@code String} and a | ||
| 40 | * {@code String} to a {@code double}, as well as other | ||
| 41 | * constants and methods useful when dealing with a | ||
| 42 | * {@code double}. | ||
| 43 | * | ||
| 44 | * @author Lee Boynton | ||
| 45 | * @author Arthur van Hoff | ||
| 46 | * @author Joseph D. Darcy | ||
| 47 | * @since JDK1.0 | ||
| 48 | */ | ||
| 49 | public final class Double extends Number implements Comparable<Double> { | ||
| 50 | /** | ||
| 51 | * A constant holding the positive infinity of type | ||
| 52 | * {@code double}. It is equal to the value returned by | ||
| 53 | * {@code Double.longBitsToDouble(0x7ff0000000000000L)}. | ||
| 54 | */ | ||
| 55 | public static final double POSITIVE_INFINITY = 1.0 / 0.0; | ||
| 56 | |||
| 57 | /** | ||
| 58 | * A constant holding the negative infinity of type | ||
| 59 | * {@code double}. It is equal to the value returned by | ||
| 60 | * {@code Double.longBitsToDouble(0xfff0000000000000L)}. | ||
| 61 | */ | ||
| 62 | public static final double NEGATIVE_INFINITY = -1.0 / 0.0; | ||
| 63 | |||
| 64 | /** | ||
| 65 | * A constant holding a Not-a-Number (NaN) value of type | ||
| 66 | * {@code double}. It is equivalent to the value returned by | ||
| 67 | * {@code Double.longBitsToDouble(0x7ff8000000000000L)}. | ||
| 68 | */ | ||
| 69 | public static final double NaN = 0.0d / 0.0; | ||
| 70 | |||
| 71 | /** | ||
| 72 | * A constant holding the largest positive finite value of type | ||
| 73 | * {@code double}, | ||
| 74 | * (2-2<sup>-52</sup>)·2<sup>1023</sup>. It is equal to | ||
| 75 | * the hexadecimal floating-point literal | ||
| 76 | * {@code 0x1.fffffffffffffP+1023} and also equal to | ||
| 77 | * {@code Double.longBitsToDouble(0x7fefffffffffffffL)}. | ||
| 78 | */ | ||
| 79 | public static final double MAX_VALUE = 0x1.fffffffffffffP+1023; // 1.7976931348623157e+308 | ||
| 80 | |||
| 81 | /** | ||
| 82 | * A constant holding the smallest positive normal value of type | ||
| 83 | * {@code double}, 2<sup>-1022</sup>. It is equal to the | ||
| 84 | * hexadecimal floating-point literal {@code 0x1.0p-1022} and also | ||
| 85 | * equal to {@code Double.longBitsToDouble(0x0010000000000000L)}. | ||
| 86 | * | ||
| 87 | * @since 1.6 | ||
| 88 | */ | ||
| 89 | public static final double MIN_NORMAL = 0x1.0p-1022; // 2.2250738585072014E-308 | ||
| 90 | |||
| 91 | /** | ||
| 92 | * A constant holding the smallest positive nonzero value of type | ||
| 93 | * {@code double}, 2<sup>-1074</sup>. It is equal to the | ||
| 94 | * hexadecimal floating-point literal | ||
| 95 | * {@code 0x0.0000000000001P-1022} and also equal to | ||
| 96 | * {@code Double.longBitsToDouble(0x1L)}. | ||
| 97 | */ | ||
| 98 | public static final double MIN_VALUE = 0x0.0000000000001P-1022; // 4.9e-324 | ||
| 99 | |||
| 100 | /** | ||
| 101 | * Maximum exponent a finite {@code double} variable may have. | ||
| 102 | * It is equal to the value returned by | ||
| 103 | * {@code Math.getExponent(Double.MAX_VALUE)}. | ||
| 104 | * | ||
| 105 | * @since 1.6 | ||
| 106 | */ | ||
| 107 | public static final int MAX_EXPONENT = 1023; | ||
| 108 | |||
| 109 | /** | ||
| 110 | * Minimum exponent a normalized {@code double} variable may | ||
| 111 | * have. It is equal to the value returned by | ||
| 112 | * {@code Math.getExponent(Double.MIN_NORMAL)}. | ||
| 113 | * | ||
| 114 | * @since 1.6 | ||
| 115 | */ | ||
| 116 | public static final int MIN_EXPONENT = -1022; | ||
| 117 | |||
| 118 | /** | ||
| 119 | * The number of bits used to represent a {@code double} value. | ||
| 120 | * | ||
| 121 | * @since 1.5 | ||
| 122 | */ | ||
| 123 | public static final int SIZE = 64; | ||
| 124 | |||
| 125 | /** | ||
| 126 | * The {@code Class} instance representing the primitive type | ||
| 127 | * {@code double}. | ||
| 128 | * | ||
| 129 | * @since JDK1.1 | ||
| 130 | */ | ||
| 131 | public static final Class<Double> TYPE = (Class<Double>) Class.getPrimitiveClass("double"); | ||
| 132 | |||
| 133 | /** | ||
| 134 | * Returns a string representation of the {@code double} | ||
| 135 | * argument. All characters mentioned below are ASCII characters. | ||
| 136 | * <ul> | ||
| 137 | * <li>If the argument is NaN, the result is the string | ||
| 138 | * "{@code NaN}". | ||
| 139 | * <li>Otherwise, the result is a string that represents the sign and | ||
| 140 | * magnitude (absolute value) of the argument. If the sign is negative, | ||
| 141 | * the first character of the result is '{@code -}' | ||
| 142 | * (<code>'\u002D'</code>); if the sign is positive, no sign character | ||
| 143 | * appears in the result. As for the magnitude <i>m</i>: | ||
| 144 | * <ul> | ||
| 145 | * <li>If <i>m</i> is infinity, it is represented by the characters | ||
| 146 | * {@code "Infinity"}; thus, positive infinity produces the result | ||
| 147 | * {@code "Infinity"} and negative infinity produces the result | ||
| 148 | * {@code "-Infinity"}. | ||
| 149 | * | ||
| 150 | * <li>If <i>m</i> is zero, it is represented by the characters | ||
| 151 | * {@code "0.0"}; thus, negative zero produces the result | ||
| 152 | * {@code "-0.0"} and positive zero produces the result | ||
| 153 | * {@code "0.0"}. | ||
| 154 | * | ||
| 155 | * <li>If <i>m</i> is greater than or equal to 10<sup>-3</sup> but less | ||
| 156 | * than 10<sup>7</sup>, then it is represented as the integer part of | ||
| 157 | * <i>m</i>, in decimal form with no leading zeroes, followed by | ||
| 158 | * '{@code .}' (<code>'\u002E'</code>), followed by one or | ||
| 159 | * more decimal digits representing the fractional part of <i>m</i>. | ||
| 160 | * | ||
| 161 | * <li>If <i>m</i> is less than 10<sup>-3</sup> or greater than or | ||
| 162 | * equal to 10<sup>7</sup>, then it is represented in so-called | ||
| 163 | * "computerized scientific notation." Let <i>n</i> be the unique | ||
| 164 | * integer such that 10<sup><i>n</i></sup> ≤ <i>m</i> {@literal <} | ||
| 165 | * 10<sup><i>n</i>+1</sup>; then let <i>a</i> be the | ||
| 166 | * mathematically exact quotient of <i>m</i> and | ||
| 167 | * 10<sup><i>n</i></sup> so that 1 ≤ <i>a</i> {@literal <} 10. The | ||
| 168 | * magnitude is then represented as the integer part of <i>a</i>, | ||
| 169 | * as a single decimal digit, followed by '{@code .}' | ||
| 170 | * (<code>'\u002E'</code>), followed by decimal digits | ||
| 171 | * representing the fractional part of <i>a</i>, followed by the | ||
| 172 | * letter '{@code E}' (<code>'\u0045'</code>), followed | ||
| 173 | * by a representation of <i>n</i> as a decimal integer, as | ||
| 174 | * produced by the method {@link Integer#toString(int)}. | ||
| 175 | * </ul> | ||
| 176 | * </ul> | ||
| 177 | * How many digits must be printed for the fractional part of | ||
| 178 | * <i>m</i> or <i>a</i>? There must be at least one digit to represent | ||
| 179 | * the fractional part, and beyond that as many, but only as many, more | ||
| 180 | * digits as are needed to uniquely distinguish the argument value from | ||
| 181 | * adjacent values of type {@code double}. That is, suppose that | ||
| 182 | * <i>x</i> is the exact mathematical value represented by the decimal | ||
| 183 | * representation produced by this method for a finite nonzero argument | ||
| 184 | * <i>d</i>. Then <i>d</i> must be the {@code double} value nearest | ||
| 185 | * to <i>x</i>; or if two {@code double} values are equally close | ||
| 186 | * to <i>x</i>, then <i>d</i> must be one of them and the least | ||
| 187 | * significant bit of the significand of <i>d</i> must be {@code 0}. | ||
| 188 | * | ||
| 189 | * <p>To create localized string representations of a floating-point | ||
| 190 | * value, use subclasses of {@link java.text.NumberFormat}. | ||
| 191 | * | ||
| 192 | * @param d the {@code double} to be converted. | ||
| 193 | * @return a string representation of the argument. | ||
| 194 | */ | ||
| 195 | public static String toString(double d) { | ||
| 196 | return new FloatingDecimal(d).toJavaFormatString(); | ||
| 197 | } | ||
| 198 | |||
| 199 | /** | ||
| 200 | * Returns a hexadecimal string representation of the | ||
| 201 | * {@code double} argument. All characters mentioned below | ||
| 202 | * are ASCII characters. | ||
| 203 | * | ||
| 204 | * <ul> | ||
| 205 | * <li>If the argument is NaN, the result is the string | ||
| 206 | * "{@code NaN}". | ||
| 207 | * <li>Otherwise, the result is a string that represents the sign | ||
| 208 | * and magnitude of the argument. If the sign is negative, the | ||
| 209 | * first character of the result is '{@code -}' | ||
| 210 | * (<code>'\u002D'</code>); if the sign is positive, no sign | ||
| 211 | * character appears in the result. As for the magnitude <i>m</i>: | ||
| 212 | * | ||
| 213 | * <ul> | ||
| 214 | * <li>If <i>m</i> is infinity, it is represented by the string | ||
| 215 | * {@code "Infinity"}; thus, positive infinity produces the | ||
| 216 | * result {@code "Infinity"} and negative infinity produces | ||
| 217 | * the result {@code "-Infinity"}. | ||
| 218 | * | ||
| 219 | * <li>If <i>m</i> is zero, it is represented by the string | ||
| 220 | * {@code "0x0.0p0"}; thus, negative zero produces the result | ||
| 221 | * {@code "-0x0.0p0"} and positive zero produces the result | ||
| 222 | * {@code "0x0.0p0"}. | ||
| 223 | * | ||
| 224 | * <li>If <i>m</i> is a {@code double} value with a | ||
| 225 | * normalized representation, substrings are used to represent the | ||
| 226 | * significand and exponent fields. The significand is | ||
| 227 | * represented by the characters {@code "0x1."} | ||
| 228 | * followed by a lowercase hexadecimal representation of the rest | ||
| 229 | * of the significand as a fraction. Trailing zeros in the | ||
| 230 | * hexadecimal representation are removed unless all the digits | ||
| 231 | * are zero, in which case a single zero is used. Next, the | ||
| 232 | * exponent is represented by {@code "p"} followed | ||
| 233 | * by a decimal string of the unbiased exponent as if produced by | ||
| 234 | * a call to {@link Integer#toString(int) Integer.toString} on the | ||
| 235 | * exponent value. | ||
| 236 | * | ||
| 237 | * <li>If <i>m</i> is a {@code double} value with a subnormal | ||
| 238 | * representation, the significand is represented by the | ||
| 239 | * characters {@code "0x0."} followed by a | ||
| 240 | * hexadecimal representation of the rest of the significand as a | ||
| 241 | * fraction. Trailing zeros in the hexadecimal representation are | ||
| 242 | * removed. Next, the exponent is represented by | ||
| 243 | * {@code "p-1022"}. Note that there must be at | ||
| 244 | * least one nonzero digit in a subnormal significand. | ||
| 245 | * | ||
| 246 | * </ul> | ||
| 247 | * | ||
| 248 | * </ul> | ||
| 249 | * | ||
| 250 | * <table border> | ||
| 251 | * <caption><h3>Examples</h3></caption> | ||
| 252 | * <tr><th>Floating-point Value</th><th>Hexadecimal String</th> | ||
| 253 | * <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td> | ||
| 254 | * <tr><td>{@code -1.0}</td> <td>{@code -0x1.0p0}</td> | ||
| 255 | * <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td> | ||
| 256 | * <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td> | ||
| 257 | * <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td> | ||
| 258 | * <tr><td>{@code 0.25}</td> <td>{@code 0x1.0p-2}</td> | ||
| 259 | * <tr><td>{@code Double.MAX_VALUE}</td> | ||
| 260 | * <td>{@code 0x1.fffffffffffffp1023}</td> | ||
| 261 | * <tr><td>{@code Minimum Normal Value}</td> | ||
| 262 | * <td>{@code 0x1.0p-1022}</td> | ||
| 263 | * <tr><td>{@code Maximum Subnormal Value}</td> | ||
| 264 | * <td>{@code 0x0.fffffffffffffp-1022}</td> | ||
| 265 | * <tr><td>{@code Double.MIN_VALUE}</td> | ||
| 266 | * <td>{@code 0x0.0000000000001p-1022}</td> | ||
| 267 | * </table> | ||
| 268 | * @param d the {@code double} to be converted. | ||
| 269 | * @return a hex string representation of the argument. | ||
| 270 | * @since 1.5 | ||
| 271 | * @author Joseph D. Darcy | ||
| 272 | */ | ||
| 273 | public static String toHexString(double d) { | ||
| 274 | /* | ||
| 275 | * Modeled after the "a" conversion specifier in C99, section | ||
| 276 | * 7.19.6.1; however, the output of this method is more | ||
| 277 | * tightly specified. | ||
| 278 | */ | ||
| 279 | if (!FpUtils.isFinite(d) ) | ||
| 280 | // For infinity and NaN, use the decimal output. | ||
| 281 | return Double.toString(d); | ||
| 282 | else { | ||
| 283 | // Initialized to maximum size of output. | ||
| 284 | StringBuffer answer = new StringBuffer(24); | ||
| 285 | |||
| 286 | if (FpUtils.rawCopySign(1.0, d) == -1.0) // value is negative, | ||
| 287 | answer.append("-"); // so append sign info | ||
| 288 | |||
| 289 | answer.append("0x"); | ||
| 290 | |||
| 291 | d = Math.abs(d); | ||
| 292 | |||
| 293 | if(d == 0.0) { | ||
| 294 | answer.append("0.0p0"); | ||
| 295 | } | ||
| 296 | else { | ||
| 297 | boolean subnormal = (d < DoubleConsts.MIN_NORMAL); | ||
| 298 | |||
| 299 | // Isolate significand bits and OR in a high-order bit | ||
| 300 | // so that the string representation has a known | ||
| 301 | // length. | ||
| 302 | long signifBits = (Double.doubleToLongBits(d) | ||
| 303 | & DoubleConsts.SIGNIF_BIT_MASK) | | ||
| 304 | 0x1000000000000000L; | ||
| 305 | |||
| 306 | // Subnormal values have a 0 implicit bit; normal | ||
| 307 | // values have a 1 implicit bit. | ||
| 308 | answer.append(subnormal ? "0." : "1."); | ||
| 309 | |||
| 310 | // Isolate the low-order 13 digits of the hex | ||
| 311 | // representation. If all the digits are zero, | ||
| 312 | // replace with a single 0; otherwise, remove all | ||
| 313 | // trailing zeros. | ||
| 314 | String signif = Long.toHexString(signifBits).substring(3,16); | ||
| 315 | answer.append(signif.equals("0000000000000") ? // 13 zeros | ||
| 316 | "0": | ||
| 317 | signif.replaceFirst("0{1,12}$", "")); | ||
| 318 | |||
| 319 | // If the value is subnormal, use the E_min exponent | ||
| 320 | // value for double; otherwise, extract and report d's | ||
| 321 | // exponent (the representation of a subnormal uses | ||
| 322 | // E_min -1). | ||
| 323 | answer.append("p" + (subnormal ? | ||
| 324 | DoubleConsts.MIN_EXPONENT: | ||
| 325 | FpUtils.getExponent(d) )); | ||
| 326 | } | ||
| 327 | return answer.toString(); | ||
| 328 | } | ||
| 329 | } | ||
| 330 | |||
| 331 | /** | ||
| 332 | * Returns a {@code Double} object holding the | ||
| 333 | * {@code double} value represented by the argument string | ||
| 334 | * {@code s}. | ||
| 335 | * | ||
| 336 | * <p>If {@code s} is {@code null}, then a | ||
| 337 | * {@code NullPointerException} is thrown. | ||
| 338 | * | ||
| 339 | * <p>Leading and trailing whitespace characters in {@code s} | ||
| 340 | * are ignored. Whitespace is removed as if by the {@link | ||
| 341 | * String#trim} method; that is, both ASCII space and control | ||
| 342 | * characters are removed. The rest of {@code s} should | ||
| 343 | * constitute a <i>FloatValue</i> as described by the lexical | ||
| 344 | * syntax rules: | ||
| 345 | * | ||
| 346 | * <blockquote> | ||
| 347 | * <dl> | ||
| 348 | * <dt><i>FloatValue:</i> | ||
| 349 | * <dd><i>Sign<sub>opt</sub></i> {@code NaN} | ||
| 350 | * <dd><i>Sign<sub>opt</sub></i> {@code Infinity} | ||
| 351 | * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i> | ||
| 352 | * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i> | ||
| 353 | * <dd><i>SignedInteger</i> | ||
| 354 | * </dl> | ||
| 355 | * | ||
| 356 | * <p> | ||
| 357 | * | ||
| 358 | * <dl> | ||
| 359 | * <dt><i>HexFloatingPointLiteral</i>: | ||
| 360 | * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i> | ||
| 361 | * </dl> | ||
| 362 | * | ||
| 363 | * <p> | ||
| 364 | * | ||
| 365 | * <dl> | ||
| 366 | * <dt><i>HexSignificand:</i> | ||
| 367 | * <dd><i>HexNumeral</i> | ||
| 368 | * <dd><i>HexNumeral</i> {@code .} | ||
| 369 | * <dd>{@code 0x} <i>HexDigits<sub>opt</sub> | ||
| 370 | * </i>{@code .}<i> HexDigits</i> | ||
| 371 | * <dd>{@code 0X}<i> HexDigits<sub>opt</sub> | ||
| 372 | * </i>{@code .} <i>HexDigits</i> | ||
| 373 | * </dl> | ||
| 374 | * | ||
| 375 | * <p> | ||
| 376 | * | ||
| 377 | * <dl> | ||
| 378 | * <dt><i>BinaryExponent:</i> | ||
| 379 | * <dd><i>BinaryExponentIndicator SignedInteger</i> | ||
| 380 | * </dl> | ||
| 381 | * | ||
| 382 | * <p> | ||
| 383 | * | ||
| 384 | * <dl> | ||
| 385 | * <dt><i>BinaryExponentIndicator:</i> | ||
| 386 | * <dd>{@code p} | ||
| 387 | * <dd>{@code P} | ||
| 388 | * </dl> | ||
| 389 | * | ||
| 390 | * </blockquote> | ||
| 391 | * | ||
| 392 | * where <i>Sign</i>, <i>FloatingPointLiteral</i>, | ||
| 393 | * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and | ||
| 394 | * <i>FloatTypeSuffix</i> are as defined in the lexical structure | ||
| 395 | * sections of | ||
| 396 | * <cite>The Java™ Language Specification</cite>, | ||
| 397 | * except that underscores are not accepted between digits. | ||
| 398 | * If {@code s} does not have the form of | ||
| 399 | * a <i>FloatValue</i>, then a {@code NumberFormatException} | ||
| 400 | * is thrown. Otherwise, {@code s} is regarded as | ||
| 401 | * representing an exact decimal value in the usual | ||
| 402 | * "computerized scientific notation" or as an exact | ||
| 403 | * hexadecimal value; this exact numerical value is then | ||
| 404 | * conceptually converted to an "infinitely precise" | ||
| 405 | * binary value that is then rounded to type {@code double} | ||
| 406 | * by the usual round-to-nearest rule of IEEE 754 floating-point | ||
| 407 | * arithmetic, which includes preserving the sign of a zero | ||
| 408 | * value. | ||
| 409 | * | ||
| 410 | * Note that the round-to-nearest rule also implies overflow and | ||
| 411 | * underflow behaviour; if the exact value of {@code s} is large | ||
| 412 | * enough in magnitude (greater than or equal to ({@link | ||
| 413 | * #MAX_VALUE} + {@link Math#ulp(double) ulp(MAX_VALUE)}/2), | ||
| 414 | * rounding to {@code double} will result in an infinity and if the | ||
| 415 | * exact value of {@code s} is small enough in magnitude (less | ||
| 416 | * than or equal to {@link #MIN_VALUE}/2), rounding to float will | ||
| 417 | * result in a zero. | ||
| 418 | * | ||
| 419 | * Finally, after rounding a {@code Double} object representing | ||
| 420 | * this {@code double} value is returned. | ||
| 421 | * | ||
| 422 | * <p> To interpret localized string representations of a | ||
| 423 | * floating-point value, use subclasses of {@link | ||
| 424 | * java.text.NumberFormat}. | ||
| 425 | * | ||
| 426 | * <p>Note that trailing format specifiers, specifiers that | ||
| 427 | * determine the type of a floating-point literal | ||
| 428 | * ({@code 1.0f} is a {@code float} value; | ||
| 429 | * {@code 1.0d} is a {@code double} value), do | ||
| 430 | * <em>not</em> influence the results of this method. In other | ||
| 431 | * words, the numerical value of the input string is converted | ||
| 432 | * directly to the target floating-point type. The two-step | ||
| 433 | * sequence of conversions, string to {@code float} followed | ||
| 434 | * by {@code float} to {@code double}, is <em>not</em> | ||
| 435 | * equivalent to converting a string directly to | ||
| 436 | * {@code double}. For example, the {@code float} | ||
| 437 | * literal {@code 0.1f} is equal to the {@code double} | ||
| 438 | * value {@code 0.10000000149011612}; the {@code float} | ||
| 439 | * literal {@code 0.1f} represents a different numerical | ||
| 440 | * value than the {@code double} literal | ||
| 441 | * {@code 0.1}. (The numerical value 0.1 cannot be exactly | ||
| 442 | * represented in a binary floating-point number.) | ||
| 443 | * | ||
| 444 | * <p>To avoid calling this method on an invalid string and having | ||
| 445 | * a {@code NumberFormatException} be thrown, the regular | ||
| 446 | * expression below can be used to screen the input string: | ||
| 447 | * | ||
| 448 | * <code> | ||
| 449 | * <pre> | ||
| 450 | * final String Digits = "(\\p{Digit}+)"; | ||
| 451 | * final String HexDigits = "(\\p{XDigit}+)"; | ||
| 452 | * // an exponent is 'e' or 'E' followed by an optionally | ||
| 453 | * // signed decimal integer. | ||
| 454 | * final String Exp = "[eE][+-]?"+Digits; | ||
| 455 | * final String fpRegex = | ||
| 456 | * ("[\\x00-\\x20]*"+ // Optional leading "whitespace" | ||
| 457 | * "[+-]?(" + // Optional sign character | ||
| 458 | * "NaN|" + // "NaN" string | ||
| 459 | * "Infinity|" + // "Infinity" string | ||
| 460 | * | ||
| 461 | * // A decimal floating-point string representing a finite positive | ||
| 462 | * // number without a leading sign has at most five basic pieces: | ||
| 463 | * // Digits . Digits ExponentPart FloatTypeSuffix | ||
| 464 | * // | ||
| 465 | * // Since this method allows integer-only strings as input | ||
| 466 | * // in addition to strings of floating-point literals, the | ||
| 467 | * // two sub-patterns below are simplifications of the grammar | ||
| 468 | * // productions from section 3.10.2 of | ||
| 469 | * // <cite>The Java™ Language Specification</cite>. | ||
| 470 | * | ||
| 471 | * // Digits ._opt Digits_opt ExponentPart_opt FloatTypeSuffix_opt | ||
| 472 | * "((("+Digits+"(\\.)?("+Digits+"?)("+Exp+")?)|"+ | ||
| 473 | * | ||
| 474 | * // . Digits ExponentPart_opt FloatTypeSuffix_opt | ||
| 475 | * "(\\.("+Digits+")("+Exp+")?)|"+ | ||
| 476 | * | ||
| 477 | * // Hexadecimal strings | ||
| 478 | * "((" + | ||
| 479 | * // 0[xX] HexDigits ._opt BinaryExponent FloatTypeSuffix_opt | ||
| 480 | * "(0[xX]" + HexDigits + "(\\.)?)|" + | ||
| 481 | * | ||
| 482 | * // 0[xX] HexDigits_opt . HexDigits BinaryExponent FloatTypeSuffix_opt | ||
| 483 | * "(0[xX]" + HexDigits + "?(\\.)" + HexDigits + ")" + | ||
| 484 | * | ||
| 485 | * ")[pP][+-]?" + Digits + "))" + | ||
| 486 | * "[fFdD]?))" + | ||
| 487 | * "[\\x00-\\x20]*");// Optional trailing "whitespace" | ||
| 488 | * | ||
| 489 | * if (Pattern.matches(fpRegex, myString)) | ||
| 490 | * Double.valueOf(myString); // Will not throw NumberFormatException | ||
| 491 | * else { | ||
| 492 | * // Perform suitable alternative action | ||
| 493 | * } | ||
| 494 | * </pre> | ||
| 495 | * </code> | ||
| 496 | * | ||
| 497 | * @param s the string to be parsed. | ||
| 498 | * @return a {@code Double} object holding the value | ||
| 499 | * represented by the {@code String} argument. | ||
| 500 | * @throws NumberFormatException if the string does not contain a | ||
| 501 | * parsable number. | ||
| 502 | */ | ||
| 503 | public static Double valueOf(String s) throws NumberFormatException { | ||
| 504 | return new Double(FloatingDecimal.readJavaFormatString(s).doubleValue()); | ||
| 505 | } | ||
| 506 | |||
| 507 | /** | ||
| 508 | * Returns a {@code Double} instance representing the specified | ||
| 509 | * {@code double} value. | ||
| 510 | * If a new {@code Double} instance is not required, this method | ||
| 511 | * should generally be used in preference to the constructor | ||
| 512 | * {@link #Double(double)}, as this method is likely to yield | ||
| 513 | * significantly better space and time performance by caching | ||
| 514 | * frequently requested values. | ||
| 515 | * | ||
| 516 | * @param d a double value. | ||
| 517 | * @return a {@code Double} instance representing {@code d}. | ||
| 518 | * @since 1.5 | ||
| 519 | */ | ||
| 520 | public static Double valueOf(double d) { | ||
| 521 | return new Double(d); | ||
| 522 | } | ||
| 523 | |||
| 524 | /** | ||
| 525 | * Returns a new {@code double} initialized to the value | ||
| 526 | * represented by the specified {@code String}, as performed | ||
| 527 | * by the {@code valueOf} method of class | ||
| 528 | * {@code Double}. | ||
| 529 | * | ||
| 530 | * @param s the string to be parsed. | ||
| 531 | * @return the {@code double} value represented by the string | ||
| 532 | * argument. | ||
| 533 | * @throws NullPointerException if the string is null | ||
| 534 | * @throws NumberFormatException if the string does not contain | ||
| 535 | * a parsable {@code double}. | ||
| 536 | * @see java.lang.Double#valueOf(String) | ||
| 537 | * @since 1.2 | ||
| 538 | */ | ||
| 539 | public static double parseDouble(String s) throws NumberFormatException { | ||
| 540 | return FloatingDecimal.readJavaFormatString(s).doubleValue(); | ||
| 541 | } | ||
| 542 | |||
| 543 | /** | ||
| 544 | * Returns {@code true} if the specified number is a | ||
| 545 | * Not-a-Number (NaN) value, {@code false} otherwise. | ||
| 546 | * | ||
| 547 | * @param v the value to be tested. | ||
| 548 | * @return {@code true} if the value of the argument is NaN; | ||
| 549 | * {@code false} otherwise. | ||
| 550 | */ | ||
| 551 | static public boolean isNaN(double v) { | ||
| 552 | return (v != v); | ||
| 553 | } | ||
| 554 | |||
| 555 | /** | ||
| 556 | * Returns {@code true} if the specified number is infinitely | ||
| 557 | * large in magnitude, {@code false} otherwise. | ||
| 558 | * | ||
| 559 | * @param v the value to be tested. | ||
| 560 | * @return {@code true} if the value of the argument is positive | ||
| 561 | * infinity or negative infinity; {@code false} otherwise. | ||
| 562 | */ | ||
| 563 | static public boolean isInfinite(double v) { | ||
| 564 | return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY); | ||
| 565 | } | ||
| 566 | |||
| 567 | /** | ||
| 568 | * The value of the Double. | ||
| 569 | * | ||
| 570 | * @serial | ||
| 571 | */ | ||
| 572 | private final double value; | ||
| 573 | |||
| 574 | /** | ||
| 575 | * Constructs a newly allocated {@code Double} object that | ||
| 576 | * represents the primitive {@code double} argument. | ||
| 577 | * | ||
| 578 | * @param value the value to be represented by the {@code Double}. | ||
| 579 | */ | ||
| 580 | public Double(double value) { | ||
| 581 | this.value = value; | ||
| 582 | } | ||
| 583 | |||
| 584 | /** | ||
| 585 | * Constructs a newly allocated {@code Double} object that | ||
| 586 | * represents the floating-point value of type {@code double} | ||
| 587 | * represented by the string. The string is converted to a | ||
| 588 | * {@code double} value as if by the {@code valueOf} method. | ||
| 589 | * | ||
| 590 | * @param s a string to be converted to a {@code Double}. | ||
| 591 | * @throws NumberFormatException if the string does not contain a | ||
| 592 | * parsable number. | ||
| 593 | * @see java.lang.Double#valueOf(java.lang.String) | ||
| 594 | */ | ||
| 595 | public Double(String s) throws NumberFormatException { | ||
| 596 | // REMIND: this is inefficient | ||
| 597 | this(valueOf(s).doubleValue()); | ||
| 598 | } | ||
| 599 | |||
| 600 | /** | ||
| 601 | * Returns {@code true} if this {@code Double} value is | ||
| 602 | * a Not-a-Number (NaN), {@code false} otherwise. | ||
| 603 | * | ||
| 604 | * @return {@code true} if the value represented by this object is | ||
| 605 | * NaN; {@code false} otherwise. | ||
| 606 | */ | ||
| 607 | public boolean isNaN() { | ||
| 608 | return isNaN(value); | ||
| 609 | } | ||
| 610 | |||
| 611 | /** | ||
| 612 | * Returns {@code true} if this {@code Double} value is | ||
| 613 | * infinitely large in magnitude, {@code false} otherwise. | ||
| 614 | * | ||
| 615 | * @return {@code true} if the value represented by this object is | ||
| 616 | * positive infinity or negative infinity; | ||
| 617 | * {@code false} otherwise. | ||
| 618 | */ | ||
| 619 | public boolean isInfinite() { | ||
| 620 | return isInfinite(value); | ||
| 621 | } | ||
| 622 | |||
| 623 | /** | ||
| 624 | * Returns a string representation of this {@code Double} object. | ||
| 625 | * The primitive {@code double} value represented by this | ||
| 626 | * object is converted to a string exactly as if by the method | ||
| 627 | * {@code toString} of one argument. | ||
| 628 | * | ||
| 629 | * @return a {@code String} representation of this object. | ||
| 630 | * @see java.lang.Double#toString(double) | ||
| 631 | */ | ||
| 632 | public String toString() { | ||
| 633 | return toString(value); | ||
| 634 | } | ||
| 635 | |||
| 636 | /** | ||
| 637 | * Returns the value of this {@code Double} as a {@code byte} (by | ||
| 638 | * casting to a {@code byte}). | ||
| 639 | * | ||
| 640 | * @return the {@code double} value represented by this object | ||
| 641 | * converted to type {@code byte} | ||
| 642 | * @since JDK1.1 | ||
| 643 | */ | ||
| 644 | public byte byteValue() { | ||
| 645 | return (byte)value; | ||
| 646 | } | ||
| 647 | |||
| 648 | /** | ||
| 649 | * Returns the value of this {@code Double} as a | ||
| 650 | * {@code short} (by casting to a {@code short}). | ||
| 651 | * | ||
| 652 | * @return the {@code double} value represented by this object | ||
| 653 | * converted to type {@code short} | ||
| 654 | * @since JDK1.1 | ||
| 655 | */ | ||
| 656 | public short shortValue() { | ||
| 657 | return (short)value; | ||
| 658 | } | ||
| 659 | |||
| 660 | /** | ||
| 661 | * Returns the value of this {@code Double} as an | ||
| 662 | * {@code int} (by casting to type {@code int}). | ||
| 663 | * | ||
| 664 | * @return the {@code double} value represented by this object | ||
| 665 | * converted to type {@code int} | ||
| 666 | */ | ||
| 667 | public int intValue() { | ||
| 668 | return (int)value; | ||
| 669 | } | ||
| 670 | |||
| 671 | /** | ||
| 672 | * Returns the value of this {@code Double} as a | ||
| 673 | * {@code long} (by casting to type {@code long}). | ||
| 674 | * | ||
| 675 | * @return the {@code double} value represented by this object | ||
| 676 | * converted to type {@code long} | ||
| 677 | */ | ||
| 678 | public long longValue() { | ||
| 679 | return (long)value; | ||
| 680 | } | ||
| 681 | |||
| 682 | /** | ||
| 683 | * Returns the {@code float} value of this | ||
| 684 | * {@code Double} object. | ||
| 685 | * | ||
| 686 | * @return the {@code double} value represented by this object | ||
| 687 | * converted to type {@code float} | ||
| 688 | * @since JDK1.0 | ||
| 689 | */ | ||
| 690 | public float floatValue() { | ||
| 691 | return (float)value; | ||
| 692 | } | ||
| 693 | |||
| 694 | /** | ||
| 695 | * Returns the {@code double} value of this | ||
| 696 | * {@code Double} object. | ||
| 697 | * | ||
| 698 | * @return the {@code double} value represented by this object | ||
| 699 | */ | ||
| 700 | public double doubleValue() { | ||
| 701 | return (double)value; | ||
| 702 | } | ||
| 703 | |||
| 704 | /** | ||
| 705 | * Returns a hash code for this {@code Double} object. The | ||
| 706 | * result is the exclusive OR of the two halves of the | ||
| 707 | * {@code long} integer bit representation, exactly as | ||
| 708 | * produced by the method {@link #doubleToLongBits(double)}, of | ||
| 709 | * the primitive {@code double} value represented by this | ||
| 710 | * {@code Double} object. That is, the hash code is the value | ||
| 711 | * of the expression: | ||
| 712 | * | ||
| 713 | * <blockquote> | ||
| 714 | * {@code (int)(v^(v>>>32))} | ||
| 715 | * </blockquote> | ||
| 716 | * | ||
| 717 | * where {@code v} is defined by: | ||
| 718 | * | ||
| 719 | * <blockquote> | ||
| 720 | * {@code long v = Double.doubleToLongBits(this.doubleValue());} | ||
| 721 | * </blockquote> | ||
| 722 | * | ||
| 723 | * @return a {@code hash code} value for this object. | ||
| 724 | */ | ||
| 725 | public int hashCode() { | ||
| 726 | long bits = doubleToLongBits(value); | ||
| 727 | return (int)(bits ^ (bits >>> 32)); | ||
| 728 | } | ||
| 729 | |||
| 730 | /** | ||
| 731 | * Compares this object against the specified object. The result | ||
| 732 | * is {@code true} if and only if the argument is not | ||
| 733 | * {@code null} and is a {@code Double} object that | ||
| 734 | * represents a {@code double} that has the same value as the | ||
| 735 | * {@code double} represented by this object. For this | ||
| 736 | * purpose, two {@code double} values are considered to be | ||
| 737 | * the same if and only if the method {@link | ||
| 738 | * #doubleToLongBits(double)} returns the identical | ||
| 739 | * {@code long} value when applied to each. | ||
| 740 | * | ||
| 741 | * <p>Note that in most cases, for two instances of class | ||
| 742 | * {@code Double}, {@code d1} and {@code d2}, the | ||
| 743 | * value of {@code d1.equals(d2)} is {@code true} if and | ||
| 744 | * only if | ||
| 745 | * | ||
| 746 | * <blockquote> | ||
| 747 | * {@code d1.doubleValue() == d2.doubleValue()} | ||
| 748 | * </blockquote> | ||
| 749 | * | ||
| 750 | * <p>also has the value {@code true}. However, there are two | ||
| 751 | * exceptions: | ||
| 752 | * <ul> | ||
| 753 | * <li>If {@code d1} and {@code d2} both represent | ||
| 754 | * {@code Double.NaN}, then the {@code equals} method | ||
| 755 | * returns {@code true}, even though | ||
| 756 | * {@code Double.NaN==Double.NaN} has the value | ||
| 757 | * {@code false}. | ||
| 758 | * <li>If {@code d1} represents {@code +0.0} while | ||
| 759 | * {@code d2} represents {@code -0.0}, or vice versa, | ||
| 760 | * the {@code equal} test has the value {@code false}, | ||
| 761 | * even though {@code +0.0==-0.0} has the value {@code true}. | ||
| 762 | * </ul> | ||
| 763 | * This definition allows hash tables to operate properly. | ||
| 764 | * @param obj the object to compare with. | ||
| 765 | * @return {@code true} if the objects are the same; | ||
| 766 | * {@code false} otherwise. | ||
| 767 | * @see java.lang.Double#doubleToLongBits(double) | ||
| 768 | */ | ||
| 769 | public boolean equals(Object obj) { | ||
| 770 | return (obj instanceof Double) | ||
| 771 | && (doubleToLongBits(((Double)obj).value) == | ||
| 772 | doubleToLongBits(value)); | ||
| 773 | } | ||
| 774 | |||
| 775 | /** | ||
| 776 | * Returns a representation of the specified floating-point value | ||
| 777 | * according to the IEEE 754 floating-point "double | ||
| 778 | * format" bit layout. | ||
| 779 | * | ||
| 780 | * <p>Bit 63 (the bit that is selected by the mask | ||
| 781 | * {@code 0x8000000000000000L}) represents the sign of the | ||
| 782 | * floating-point number. Bits | ||
| 783 | * 62-52 (the bits that are selected by the mask | ||
| 784 | * {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0 | ||
| 785 | * (the bits that are selected by the mask | ||
| 786 | * {@code 0x000fffffffffffffL}) represent the significand | ||
| 787 | * (sometimes called the mantissa) of the floating-point number. | ||
| 788 | * | ||
| 789 | * <p>If the argument is positive infinity, the result is | ||
| 790 | * {@code 0x7ff0000000000000L}. | ||
| 791 | * | ||
| 792 | * <p>If the argument is negative infinity, the result is | ||
| 793 | * {@code 0xfff0000000000000L}. | ||
| 794 | * | ||
| 795 | * <p>If the argument is NaN, the result is | ||
| 796 | * {@code 0x7ff8000000000000L}. | ||
| 797 | * | ||
| 798 | * <p>In all cases, the result is a {@code long} integer that, when | ||
| 799 | * given to the {@link #longBitsToDouble(long)} method, will produce a | ||
| 800 | * floating-point value the same as the argument to | ||
| 801 | * {@code doubleToLongBits} (except all NaN values are | ||
| 802 | * collapsed to a single "canonical" NaN value). | ||
| 803 | * | ||
| 804 | * @param value a {@code double} precision floating-point number. | ||
| 805 | * @return the bits that represent the floating-point number. | ||
| 806 | */ | ||
| 807 | public static long doubleToLongBits(double value) { | ||
| 808 | long result = doubleToRawLongBits(value); | ||
| 809 | // Check for NaN based on values of bit fields, maximum | ||
| 810 | // exponent and nonzero significand. | ||
| 811 | if ( ((result & DoubleConsts.EXP_BIT_MASK) == | ||
| 812 | DoubleConsts.EXP_BIT_MASK) && | ||
| 813 | (result & DoubleConsts.SIGNIF_BIT_MASK) != 0L) | ||
| 814 | result = 0x7ff8000000000000L; | ||
| 815 | return result; | ||
| 816 | } | ||
| 817 | |||
| 818 | /** | ||
| 819 | * Returns a representation of the specified floating-point value | ||
| 820 | * according to the IEEE 754 floating-point "double | ||
| 821 | * format" bit layout, preserving Not-a-Number (NaN) values. | ||
| 822 | * | ||
| 823 | * <p>Bit 63 (the bit that is selected by the mask | ||
| 824 | * {@code 0x8000000000000000L}) represents the sign of the | ||
| 825 | * floating-point number. Bits | ||
| 826 | * 62-52 (the bits that are selected by the mask | ||
| 827 | * {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0 | ||
| 828 | * (the bits that are selected by the mask | ||
| 829 | * {@code 0x000fffffffffffffL}) represent the significand | ||
| 830 | * (sometimes called the mantissa) of the floating-point number. | ||
| 831 | * | ||
| 832 | * <p>If the argument is positive infinity, the result is | ||
| 833 | * {@code 0x7ff0000000000000L}. | ||
| 834 | * | ||
| 835 | * <p>If the argument is negative infinity, the result is | ||
| 836 | * {@code 0xfff0000000000000L}. | ||
| 837 | * | ||
| 838 | * <p>If the argument is NaN, the result is the {@code long} | ||
| 839 | * integer representing the actual NaN value. Unlike the | ||
| 840 | * {@code doubleToLongBits} method, | ||
| 841 | * {@code doubleToRawLongBits} does not collapse all the bit | ||
| 842 | * patterns encoding a NaN to a single "canonical" NaN | ||
| 843 | * value. | ||
| 844 | * | ||
| 845 | * <p>In all cases, the result is a {@code long} integer that, | ||
| 846 | * when given to the {@link #longBitsToDouble(long)} method, will | ||
| 847 | * produce a floating-point value the same as the argument to | ||
| 848 | * {@code doubleToRawLongBits}. | ||
| 849 | * | ||
| 850 | * @param value a {@code double} precision floating-point number. | ||
| 851 | * @return the bits that represent the floating-point number. | ||
| 852 | * @since 1.3 | ||
| 853 | */ | ||
| 854 | public static native long doubleToRawLongBits(double value); | ||
| 855 | |||
| 856 | /** | ||
| 857 | * Returns the {@code double} value corresponding to a given | ||
| 858 | * bit representation. | ||
| 859 | * The argument is considered to be a representation of a | ||
| 860 | * floating-point value according to the IEEE 754 floating-point | ||
| 861 | * "double format" bit layout. | ||
| 862 | * | ||
| 863 | * <p>If the argument is {@code 0x7ff0000000000000L}, the result | ||
| 864 | * is positive infinity. | ||
| 865 | * | ||
| 866 | * <p>If the argument is {@code 0xfff0000000000000L}, the result | ||
| 867 | * is negative infinity. | ||
| 868 | * | ||
| 869 | * <p>If the argument is any value in the range | ||
| 870 | * {@code 0x7ff0000000000001L} through | ||
| 871 | * {@code 0x7fffffffffffffffL} or in the range | ||
| 872 | * {@code 0xfff0000000000001L} through | ||
| 873 | * {@code 0xffffffffffffffffL}, the result is a NaN. No IEEE | ||
| 874 | * 754 floating-point operation provided by Java can distinguish | ||
| 875 | * between two NaN values of the same type with different bit | ||
| 876 | * patterns. Distinct values of NaN are only distinguishable by | ||
| 877 | * use of the {@code Double.doubleToRawLongBits} method. | ||
| 878 | * | ||
| 879 | * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three | ||
| 880 | * values that can be computed from the argument: | ||
| 881 | * | ||
| 882 | * <blockquote><pre> | ||
| 883 | * int s = ((bits >> 63) == 0) ? 1 : -1; | ||
| 884 | * int e = (int)((bits >> 52) & 0x7ffL); | ||
| 885 | * long m = (e == 0) ? | ||
| 886 | * (bits & 0xfffffffffffffL) << 1 : | ||
| 887 | * (bits & 0xfffffffffffffL) | 0x10000000000000L; | ||
| 888 | * </pre></blockquote> | ||
| 889 | * | ||
| 890 | * Then the floating-point result equals the value of the mathematical | ||
| 891 | * expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-1075</sup>. | ||
| 892 | * | ||
| 893 | * <p>Note that this method may not be able to return a | ||
| 894 | * {@code double} NaN with exactly same bit pattern as the | ||
| 895 | * {@code long} argument. IEEE 754 distinguishes between two | ||
| 896 | * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The | ||
| 897 | * differences between the two kinds of NaN are generally not | ||
| 898 | * visible in Java. Arithmetic operations on signaling NaNs turn | ||
| 899 | * them into quiet NaNs with a different, but often similar, bit | ||
| 900 | * pattern. However, on some processors merely copying a | ||
| 901 | * signaling NaN also performs that conversion. In particular, | ||
| 902 | * copying a signaling NaN to return it to the calling method | ||
| 903 | * may perform this conversion. So {@code longBitsToDouble} | ||
| 904 | * may not be able to return a {@code double} with a | ||
| 905 | * signaling NaN bit pattern. Consequently, for some | ||
| 906 | * {@code long} values, | ||
| 907 | * {@code doubleToRawLongBits(longBitsToDouble(start))} may | ||
| 908 | * <i>not</i> equal {@code start}. Moreover, which | ||
| 909 | * particular bit patterns represent signaling NaNs is platform | ||
| 910 | * dependent; although all NaN bit patterns, quiet or signaling, | ||
| 911 | * must be in the NaN range identified above. | ||
| 912 | * | ||
| 913 | * @param bits any {@code long} integer. | ||
| 914 | * @return the {@code double} floating-point value with the same | ||
| 915 | * bit pattern. | ||
| 916 | */ | ||
| 917 | public static native double longBitsToDouble(long bits); | ||
| 918 | |||
| 919 | /** | ||
| 920 | * Compares two {@code Double} objects numerically. There | ||
| 921 | * are two ways in which comparisons performed by this method | ||
| 922 | * differ from those performed by the Java language numerical | ||
| 923 | * comparison operators ({@code <, <=, ==, >=, >}) | ||
| 924 | * when applied to primitive {@code double} values: | ||
| 925 | * <ul><li> | ||
| 926 | * {@code Double.NaN} is considered by this method | ||
| 927 | * to be equal to itself and greater than all other | ||
| 928 | * {@code double} values (including | ||
| 929 | * {@code Double.POSITIVE_INFINITY}). | ||
| 930 | * <li> | ||
| 931 | * {@code 0.0d} is considered by this method to be greater | ||
| 932 | * than {@code -0.0d}. | ||
| 933 | * </ul> | ||
| 934 | * This ensures that the <i>natural ordering</i> of | ||
| 935 | * {@code Double} objects imposed by this method is <i>consistent | ||
| 936 | * with equals</i>. | ||
| 937 | * | ||
| 938 | * @param anotherDouble the {@code Double} to be compared. | ||
| 939 | * @return the value {@code 0} if {@code anotherDouble} is | ||
| 940 | * numerically equal to this {@code Double}; a value | ||
| 941 | * less than {@code 0} if this {@code Double} | ||
| 942 | * is numerically less than {@code anotherDouble}; | ||
| 943 | * and a value greater than {@code 0} if this | ||
| 944 | * {@code Double} is numerically greater than | ||
| 945 | * {@code anotherDouble}. | ||
| 946 | * | ||
| 947 | * @since 1.2 | ||
| 948 | */ | ||
| 949 | public int compareTo(Double anotherDouble) { | ||
| 950 | return Double.compare(value, anotherDouble.value); | ||
| 951 | } | ||
| 952 | |||
| 953 | /** | ||
| 954 | * Compares the two specified {@code double} values. The sign | ||
| 955 | * of the integer value returned is the same as that of the | ||
| 956 | * integer that would be returned by the call: | ||
| 957 | * <pre> | ||
| 958 | * new Double(d1).compareTo(new Double(d2)) | ||
| 959 | * </pre> | ||
| 960 | * | ||
| 961 | * @param d1 the first {@code double} to compare | ||
| 962 | * @param d2 the second {@code double} to compare | ||
| 963 | * @return the value {@code 0} if {@code d1} is | ||
| 964 | * numerically equal to {@code d2}; a value less than | ||
| 965 | * {@code 0} if {@code d1} is numerically less than | ||
| 966 | * {@code d2}; and a value greater than {@code 0} | ||
| 967 | * if {@code d1} is numerically greater than | ||
| 968 | * {@code d2}. | ||
| 969 | * @since 1.4 | ||
| 970 | */ | ||
| 971 | public static int compare(double d1, double d2) { | ||
| 972 | if (d1 < d2) | ||
| 973 | return -1; // Neither val is NaN, thisVal is smaller | ||
| 974 | if (d1 > d2) | ||
| 975 | return 1; // Neither val is NaN, thisVal is larger | ||
| 976 | |||
| 977 | // Cannot use doubleToRawLongBits because of possibility of NaNs. | ||
| 978 | long thisBits = Double.doubleToLongBits(d1); | ||
| 979 | long anotherBits = Double.doubleToLongBits(d2); | ||
| 980 | |||
| 981 | return (thisBits == anotherBits ? 0 : // Values are equal | ||
| 982 | (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN) | ||
| 983 | 1)); // (0.0, -0.0) or (NaN, !NaN) | ||
| 984 | } | ||
| 985 | |||
| 986 | /** use serialVersionUID from JDK 1.0.2 for interoperability */ | ||
| 987 | private static final long serialVersionUID = -9172774392245257468L; | ||
| 988 | } | ||