1 /* 2 * Copyright (c) 1996, 2013, 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 jdk.internal.HotSpotIntrinsicCandidate; 29 30 /** 31 * 32 * The {@code Byte} class wraps a value of primitive type {@code byte} 33 * in an object. An object of type {@code Byte} contains a single 34 * field whose type is {@code byte}. 35 * 36 * <p>In addition, this class provides several methods for converting 37 * a {@code byte} to a {@code String} and a {@code String} to a {@code 38 * byte}, as well as other constants and methods useful when dealing 39 * with a {@code byte}. 40 * 41 * @author Nakul Saraiya 42 * @author Joseph D. Darcy 43 * @see java.lang.Number 44 * @since 1.1 45 */ 46 public final class Byte extends Number implements Comparable<Byte> { 47 48 /** 49 * A constant holding the minimum value a {@code byte} can 50 * have, -2<sup>7</sup>. 51 */ 52 public static final byte MIN_VALUE = -128; 53 54 /** 55 * A constant holding the maximum value a {@code byte} can 56 * have, 2<sup>7</sup>-1. 57 */ 58 public static final byte MAX_VALUE = 127; 59 60 /** 61 * The {@code Class} instance representing the primitive type 62 * {@code byte}. 63 */ 64 @SuppressWarnings("unchecked") 65 public static final Class<Byte> TYPE = (Class<Byte>) Class.getPrimitiveClass("byte"); 66 67 /** 68 * Zero {@code Byte} constant. 69 */ 70 private static final Byte ZERO = new Byte((byte)0); 71 72 /** 73 * Returns a new {@code String} object representing the 74 * specified {@code byte}. The radix is assumed to be 10. 75 * 76 * @param b the {@code byte} to be converted 77 * @return the string representation of the specified {@code byte} 78 * @see java.lang.Integer#toString(int) 79 */ 80 public static String toString(byte b) { 81 return Integer.toString((int)b, 10); 82 } 83 84 private static class ByteCache { 85 private ByteCache(){} 86 87 static final Byte cache[] = new Byte[-(-128) + 127 + 1]; 88 89 static { 90 for(int i = 0; i < cache.length; i++) { 91 int val = i - 128; 92 cache[i] = (val == 0) ? ZERO : new Byte((byte)val); 93 } 94 } 95 } 96 97 /** 98 * Returns a {@code Byte} instance representing the specified 99 * {@code byte} value. 100 * If a new {@code Byte} instance is not required, this method 101 * should generally be used in preference to the constructor 102 * {@link #Byte(byte)}, as this method is likely to yield 103 * significantly better space and time performance since 104 * all byte values are cached. 105 * 106 * @param b a byte value. 107 * @return a {@code Byte} instance representing {@code b}. 108 * @since 1.5 109 */ 110 @HotSpotIntrinsicCandidate 111 public static Byte valueOf(byte b) { 112 final int offset = 128; 113 return ByteCache.cache[(int)b + offset]; 114 } 115 116 /** 117 * Parses the string argument as a signed {@code byte} in the 118 * radix specified by the second argument. The characters in the 119 * string must all be digits, of the specified radix (as 120 * determined by whether {@link java.lang.Character#digit(char, 121 * int)} returns a nonnegative value) except that the first 122 * character may be an ASCII minus sign {@code '-'} 123 * ({@code '\u005Cu002D'}) to indicate a negative value or an 124 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to 125 * indicate a positive value. The resulting {@code byte} value is 126 * returned. 127 * 128 * <p>An exception of type {@code NumberFormatException} is 129 * thrown if any of the following situations occurs: 130 * <ul> 131 * <li> The first argument is {@code null} or is a string of 132 * length zero. 133 * 134 * <li> The radix is either smaller than {@link 135 * java.lang.Character#MIN_RADIX} or larger than {@link 136 * java.lang.Character#MAX_RADIX}. 137 * 138 * <li> Any character of the string is not a digit of the 139 * specified radix, except that the first character may be a minus 140 * sign {@code '-'} ({@code '\u005Cu002D'}) or plus sign 141 * {@code '+'} ({@code '\u005Cu002B'}) provided that the 142 * string is longer than length 1. 143 * 144 * <li> The value represented by the string is not a value of type 145 * {@code byte}. 146 * </ul> 147 * 148 * @param s the {@code String} containing the 149 * {@code byte} 150 * representation to be parsed 151 * @param radix the radix to be used while parsing {@code s} 152 * @return the {@code byte} value represented by the string 153 * argument in the specified radix 154 * @throws NumberFormatException If the string does 155 * not contain a parsable {@code byte}. 156 */ 157 public static byte parseByte(String s, int radix) 158 throws NumberFormatException { 159 int i = Integer.parseInt(s, radix); 160 if (i < MIN_VALUE || i > MAX_VALUE) 161 throw new NumberFormatException( 162 "Value out of range. Value:\"" + s + "\" Radix:" + radix); 163 return (byte)i; 164 } 165 166 /** 167 * Parses the string argument as a signed decimal {@code 168 * byte}. The characters in the string must all be decimal digits, 169 * except that the first character may be an ASCII minus sign 170 * {@code '-'} ({@code '\u005Cu002D'}) to indicate a negative 171 * value or an ASCII plus sign {@code '+'} 172 * ({@code '\u005Cu002B'}) to indicate a positive value. The 173 * resulting {@code byte} value is returned, exactly as if the 174 * argument and the radix 10 were given as arguments to the {@link 175 * #parseByte(java.lang.String, int)} method. 176 * 177 * @param s a {@code String} containing the 178 * {@code byte} representation to be parsed 179 * @return the {@code byte} value represented by the 180 * argument in decimal 181 * @throws NumberFormatException if the string does not 182 * contain a parsable {@code byte}. 183 */ 184 public static byte parseByte(String s) throws NumberFormatException { 185 return parseByte(s, 10); 186 } 187 188 /** 189 * Returns a {@code Byte} object holding the value 190 * extracted from the specified {@code String} when parsed 191 * with the radix given by the second argument. The first argument 192 * is interpreted as representing a signed {@code byte} in 193 * the radix specified by the second argument, exactly as if the 194 * argument were given to the {@link #parseByte(java.lang.String, 195 * int)} method. The result is a {@code Byte} object that 196 * represents the {@code byte} value specified by the string. 197 * 198 * <p> In other words, this method returns a {@code Byte} object 199 * equal to the value of: 200 * 201 * <blockquote> 202 * {@code new Byte(Byte.parseByte(s, radix))} 203 * </blockquote> 204 * 205 * @param s the string to be parsed 206 * @param radix the radix to be used in interpreting {@code s} 207 * @return a {@code Byte} object holding the value 208 * represented by the string argument in the 209 * specified radix. 210 * @throws NumberFormatException If the {@code String} does 211 * not contain a parsable {@code byte}. 212 */ 213 public static Byte valueOf(String s, int radix) 214 throws NumberFormatException { 215 return valueOf(parseByte(s, radix)); 216 } 217 218 /** 219 * Returns a {@code Byte} object holding the value 220 * given by the specified {@code String}. The argument is 221 * interpreted as representing a signed decimal {@code byte}, 222 * exactly as if the argument were given to the {@link 223 * #parseByte(java.lang.String)} method. The result is a 224 * {@code Byte} object that represents the {@code byte} 225 * value specified by the string. 226 * 227 * <p> In other words, this method returns a {@code Byte} object 228 * equal to the value of: 229 * 230 * <blockquote> 231 * {@code new Byte(Byte.parseByte(s))} 232 * </blockquote> 233 * 234 * @param s the string to be parsed 235 * @return a {@code Byte} object holding the value 236 * represented by the string argument 237 * @throws NumberFormatException If the {@code String} does 238 * not contain a parsable {@code byte}. 239 */ 240 public static Byte valueOf(String s) throws NumberFormatException { 241 return valueOf(s, 10); 242 } 243 244 /** 245 * Decodes a {@code String} into a {@code Byte}. 246 * Accepts decimal, hexadecimal, and octal numbers given by 247 * the following grammar: 248 * 249 * <blockquote> 250 * <dl> 251 * <dt><i>DecodableString:</i> 252 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i> 253 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i> 254 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i> 255 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i> 256 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i> 257 * 258 * <dt><i>Sign:</i> 259 * <dd>{@code -} 260 * <dd>{@code +} 261 * </dl> 262 * </blockquote> 263 * 264 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i> 265 * are as defined in section 3.10.1 of 266 * <cite>The Java™ Language Specification</cite>, 267 * except that underscores are not accepted between digits. 268 * 269 * <p>The sequence of characters following an optional 270 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}", 271 * "{@code #}", or leading zero) is parsed as by the {@code 272 * Byte.parseByte} method with the indicated radix (10, 16, or 8). 273 * This sequence of characters must represent a positive value or 274 * a {@link NumberFormatException} will be thrown. The result is 275 * negated if first character of the specified {@code String} is 276 * the minus sign. No whitespace characters are permitted in the 277 * {@code String}. 278 * 279 * @param nm the {@code String} to decode. 280 * @return a {@code Byte} object holding the {@code byte} 281 * value represented by {@code nm} 282 * @throws NumberFormatException if the {@code String} does not 283 * contain a parsable {@code byte}. 284 * @see java.lang.Byte#parseByte(java.lang.String, int) 285 */ 286 public static Byte decode(String nm) throws NumberFormatException { 287 int i = Integer.decode(nm); 288 if (i < MIN_VALUE || i > MAX_VALUE) 289 throw new NumberFormatException( 290 "Value " + i + " out of range from input " + nm); 291 return valueOf((byte)i); 292 } 293 294 /** 295 * The value of the {@code Byte}. 296 * 297 * @serial 298 */ 299 private final byte value; 300 301 /** 302 * Constructs a newly allocated {@code Byte} object that 303 * represents the specified {@code byte} value. 304 * 305 * @param value the value to be represented by the 306 * {@code Byte}. 307 */ 308 public Byte(byte value) { 309 this.value = value; 310 } 311 312 /** 313 * Constructs a newly allocated {@code Byte} object that 314 * represents the {@code byte} value indicated by the 315 * {@code String} parameter. The string is converted to a 316 * {@code byte} value in exactly the manner used by the 317 * {@code parseByte} method for radix 10. 318 * 319 * @param s the {@code String} to be converted to a 320 * {@code Byte} 321 * @throws NumberFormatException If the {@code String} 322 * does not contain a parsable {@code byte}. 323 * @see java.lang.Byte#parseByte(java.lang.String, int) 324 */ 325 public Byte(String s) throws NumberFormatException { 326 this.value = parseByte(s, 10); 327 } 328 329 /** 330 * Returns the value of this {@code Byte} as a 331 * {@code byte}. 332 */ 333 @HotSpotIntrinsicCandidate 334 public byte byteValue() { 335 return value; 336 } 337 338 /** 339 * Returns the value of this {@code Byte} as a {@code short} after 340 * a widening primitive conversion. 341 * @jls 5.1.2 Widening Primitive Conversions 342 */ 343 public short shortValue() { 344 return (short)value; 345 } 346 347 /** 348 * Returns the value of this {@code Byte} as an {@code int} after 349 * a widening primitive conversion. 350 * @jls 5.1.2 Widening Primitive Conversions 351 */ 352 public int intValue() { 353 return (int)value; 354 } 355 356 /** 357 * Returns the value of this {@code Byte} as a {@code long} after 358 * a widening primitive conversion. 359 * @jls 5.1.2 Widening Primitive Conversions 360 */ 361 public long longValue() { 362 return (long)value; 363 } 364 365 /** 366 * Returns the value of this {@code Byte} as a {@code float} after 367 * a widening primitive conversion. 368 * @jls 5.1.2 Widening Primitive Conversions 369 */ 370 public float floatValue() { 371 return (float)value; 372 } 373 374 /** 375 * Returns the value of this {@code Byte} as a {@code double} 376 * after a widening primitive conversion. 377 * @jls 5.1.2 Widening Primitive Conversions 378 */ 379 public double doubleValue() { 380 return (double)value; 381 } 382 383 /** 384 * Returns a {@code String} object representing this 385 * {@code Byte}'s value. The value is converted to signed 386 * decimal representation and returned as a string, exactly as if 387 * the {@code byte} value were given as an argument to the 388 * {@link java.lang.Byte#toString(byte)} method. 389 * 390 * @return a string representation of the value of this object in 391 * base 10. 392 */ 393 public String toString() { 394 return Integer.toString((int)value); 395 } 396 397 /** 398 * Returns a hash code for this {@code Byte}; equal to the result 399 * of invoking {@code intValue()}. 400 * 401 * @return a hash code value for this {@code Byte} 402 */ 403 @Override 404 public int hashCode() { 405 return Byte.hashCode(value); 406 } 407 408 /** 409 * Returns a hash code for a {@code byte} value; compatible with 410 * {@code Byte.hashCode()}. 411 * 412 * @param value the value to hash 413 * @return a hash code value for a {@code byte} value. 414 * @since 1.8 415 */ 416 public static int hashCode(byte value) { 417 return (int)value; 418 } 419 420 /** 421 * Compares this object to the specified object. The result is 422 * {@code true} if and only if the argument is not 423 * {@code null} and is a {@code Byte} object that 424 * contains the same {@code byte} value as this object. 425 * 426 * @param obj the object to compare with 427 * @return {@code true} if the objects are the same; 428 * {@code false} otherwise. 429 */ 430 public boolean equals(Object obj) { 431 if (obj instanceof Byte) { 432 return value == ((Byte)obj).byteValue(); 433 } 434 return false; 435 } 436 437 /** 438 * Compares two {@code Byte} objects numerically. 439 * 440 * @param anotherByte the {@code Byte} to be compared. 441 * @return the value {@code 0} if this {@code Byte} is 442 * equal to the argument {@code Byte}; a value less than 443 * {@code 0} if this {@code Byte} is numerically less 444 * than the argument {@code Byte}; and a value greater than 445 * {@code 0} if this {@code Byte} is numerically 446 * greater than the argument {@code Byte} (signed 447 * comparison). 448 * @since 1.2 449 */ 450 public int compareTo(Byte anotherByte) { 451 return compare(this.value, anotherByte.value); 452 } 453 454 /** 455 * Compares two {@code byte} values numerically. 456 * The value returned is identical to what would be returned by: 457 * <pre> 458 * Byte.valueOf(x).compareTo(Byte.valueOf(y)) 459 * </pre> 460 * 461 * @param x the first {@code byte} to compare 462 * @param y the second {@code byte} to compare 463 * @return the value {@code 0} if {@code x == y}; 464 * a value less than {@code 0} if {@code x < y}; and 465 * a value greater than {@code 0} if {@code x > y} 466 * @since 1.7 467 */ 468 public static int compare(byte x, byte y) { 469 return x - y; 470 } 471 472 /** 473 * Compares two {@code byte} values numerically treating the values 474 * as unsigned. 475 * 476 * @param x the first {@code byte} to compare 477 * @param y the second {@code byte} to compare 478 * @return the value {@code 0} if {@code x == y}; a value less 479 * than {@code 0} if {@code x < y} as unsigned values; and 480 * a value greater than {@code 0} if {@code x > y} as 481 * unsigned values 482 * @since 9 483 */ 484 public static int compareUnsigned(byte x, byte y) { 485 return Byte.toUnsignedInt(x) - Byte.toUnsignedInt(y); 486 } 487 488 /** 489 * Converts the argument to an {@code int} by an unsigned 490 * conversion. In an unsigned conversion to an {@code int}, the 491 * high-order 24 bits of the {@code int} are zero and the 492 * low-order 8 bits are equal to the bits of the {@code byte} argument. 493 * 494 * Consequently, zero and positive {@code byte} values are mapped 495 * to a numerically equal {@code int} value and negative {@code 496 * byte} values are mapped to an {@code int} value equal to the 497 * input plus 2<sup>8</sup>. 498 * 499 * @param x the value to convert to an unsigned {@code int} 500 * @return the argument converted to {@code int} by an unsigned 501 * conversion 502 * @since 1.8 503 */ 504 public static int toUnsignedInt(byte x) { 505 return ((int) x) & 0xff; 506 } 507 508 /** 509 * Converts the argument to a {@code long} by an unsigned 510 * conversion. In an unsigned conversion to a {@code long}, the 511 * high-order 56 bits of the {@code long} are zero and the 512 * low-order 8 bits are equal to the bits of the {@code byte} argument. 513 * 514 * Consequently, zero and positive {@code byte} values are mapped 515 * to a numerically equal {@code long} value and negative {@code 516 * byte} values are mapped to a {@code long} value equal to the 517 * input plus 2<sup>8</sup>. 518 * 519 * @param x the value to convert to an unsigned {@code long} 520 * @return the argument converted to {@code long} by an unsigned 521 * conversion 522 * @since 1.8 523 */ 524 public static long toUnsignedLong(byte x) { 525 return ((long) x) & 0xffL; 526 } 527 528 529 /** 530 * The number of bits used to represent a {@code byte} value in two's 531 * complement binary form. 532 * 533 * @since 1.5 534 */ 535 public static final int SIZE = 8; 536 537 /** 538 * The number of bytes used to represent a {@code byte} value in two's 539 * complement binary form. 540 * 541 * @since 1.8 542 */ 543 public static final int BYTES = SIZE / Byte.SIZE; 544 545 /** use serialVersionUID from JDK 1.1. for interoperability */ 546 private static final long serialVersionUID = -7183698231559129828L; 547 }