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 import libcore.util.HexEncoding; 30 31 /** 32 * 33 * The {@code Byte} class wraps a value of primitive type {@code byte} 34 * in an object. An object of type {@code Byte} contains a single 35 * field whose type is {@code byte}. 36 * 37 * <p>In addition, this class provides several methods for converting 38 * a {@code byte} to a {@code String} and a {@code String} to a {@code 39 * byte}, as well as other constants and methods useful when dealing 40 * with a {@code byte}. 41 * 42 * @author Nakul Saraiya 43 * @author Joseph D. Darcy 44 * @see java.lang.Number 45 * @since 1.1 46 */ 47 public final class Byte extends Number implements Comparable<Byte> { 48 49 /** 50 * A constant holding the minimum value a {@code byte} can 51 * have, -2<sup>7</sup>. 52 */ 53 public static final byte MIN_VALUE = -128; 54 55 /** 56 * A constant holding the maximum value a {@code byte} can 57 * have, 2<sup>7</sup>-1. 58 */ 59 public static final byte MAX_VALUE = 127; 60 61 /** 62 * The {@code Class} instance representing the primitive type 63 * {@code byte}. 64 */ 65 @SuppressWarnings("unchecked") 66 public static final Class<Byte> TYPE = (Class<Byte>) Class.getPrimitiveClass("byte"); 67 68 /** 69 * Returns a new {@code String} object representing the 70 * specified {@code byte}. The radix is assumed to be 10. 71 * 72 * @param b the {@code byte} to be converted 73 * @return the string representation of the specified {@code byte} 74 * @see java.lang.Integer#toString(int) 75 */ toString(byte b)76 public static String toString(byte b) { 77 return Integer.toString((int)b, 10); 78 } 79 80 private static class ByteCache { ByteCache()81 private ByteCache(){} 82 83 static final Byte cache[] = new Byte[-(-128) + 127 + 1]; 84 85 static { 86 for(int i = 0; i < cache.length; i++) 87 cache[i] = new Byte((byte)(i - 128)); 88 } 89 } 90 91 /** 92 * Returns a {@code Byte} instance representing the specified 93 * {@code byte} value. 94 * If a new {@code Byte} instance is not required, this method 95 * should generally be used in preference to the constructor 96 * {@link #Byte(byte)}, as this method is likely to yield 97 * significantly better space and time performance since 98 * all byte values are cached. 99 * 100 * @param b a byte value. 101 * @return a {@code Byte} instance representing {@code b}. 102 * @since 1.5 103 */ 104 @HotSpotIntrinsicCandidate valueOf(byte b)105 public static Byte valueOf(byte b) { 106 final int offset = 128; 107 return ByteCache.cache[(int)b + offset]; 108 } 109 110 /** 111 * Parses the string argument as a signed {@code byte} in the 112 * radix specified by the second argument. The characters in the 113 * string must all be digits, of the specified radix (as 114 * determined by whether {@link java.lang.Character#digit(char, 115 * int)} returns a nonnegative value) except that the first 116 * character may be an ASCII minus sign {@code '-'} 117 * ({@code '\u005Cu002D'}) to indicate a negative value or an 118 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to 119 * indicate a positive value. The resulting {@code byte} value is 120 * returned. 121 * 122 * <p>An exception of type {@code NumberFormatException} is 123 * thrown if any of the following situations occurs: 124 * <ul> 125 * <li> The first argument is {@code null} or is a string of 126 * length zero. 127 * 128 * <li> The radix is either smaller than {@link 129 * java.lang.Character#MIN_RADIX} or larger than {@link 130 * java.lang.Character#MAX_RADIX}. 131 * 132 * <li> Any character of the string is not a digit of the 133 * specified radix, except that the first character may be a minus 134 * sign {@code '-'} ({@code '\u005Cu002D'}) or plus sign 135 * {@code '+'} ({@code '\u005Cu002B'}) provided that the 136 * string is longer than length 1. 137 * 138 * <li> The value represented by the string is not a value of type 139 * {@code byte}. 140 * </ul> 141 * 142 * @param s the {@code String} containing the 143 * {@code byte} 144 * representation to be parsed 145 * @param radix the radix to be used while parsing {@code s} 146 * @return the {@code byte} value represented by the string 147 * argument in the specified radix 148 * @throws NumberFormatException If the string does 149 * not contain a parsable {@code byte}. 150 */ parseByte(String s, int radix)151 public static byte parseByte(String s, int radix) 152 throws NumberFormatException { 153 int i = Integer.parseInt(s, radix); 154 if (i < MIN_VALUE || i > MAX_VALUE) 155 throw new NumberFormatException( 156 "Value out of range. Value:\"" + s + "\" Radix:" + radix); 157 return (byte)i; 158 } 159 160 /** 161 * Parses the string argument as a signed decimal {@code 162 * byte}. The characters in the string must all be decimal digits, 163 * except that the first character may be an ASCII minus sign 164 * {@code '-'} ({@code '\u005Cu002D'}) to indicate a negative 165 * value or an ASCII plus sign {@code '+'} 166 * ({@code '\u005Cu002B'}) to indicate a positive value. The 167 * resulting {@code byte} value is returned, exactly as if the 168 * argument and the radix 10 were given as arguments to the {@link 169 * #parseByte(java.lang.String, int)} method. 170 * 171 * @param s a {@code String} containing the 172 * {@code byte} representation to be parsed 173 * @return the {@code byte} value represented by the 174 * argument in decimal 175 * @throws NumberFormatException if the string does not 176 * contain a parsable {@code byte}. 177 */ parseByte(String s)178 public static byte parseByte(String s) throws NumberFormatException { 179 return parseByte(s, 10); 180 } 181 182 /** 183 * Returns a {@code Byte} object holding the value 184 * extracted from the specified {@code String} when parsed 185 * with the radix given by the second argument. The first argument 186 * is interpreted as representing a signed {@code byte} in 187 * the radix specified by the second argument, exactly as if the 188 * argument were given to the {@link #parseByte(java.lang.String, 189 * int)} method. The result is a {@code Byte} object that 190 * represents the {@code byte} value specified by the string. 191 * 192 * <p> In other words, this method returns a {@code Byte} object 193 * equal to the value of: 194 * 195 * <blockquote> 196 * {@code new Byte(Byte.parseByte(s, radix))} 197 * </blockquote> 198 * 199 * @param s the string to be parsed 200 * @param radix the radix to be used in interpreting {@code s} 201 * @return a {@code Byte} object holding the value 202 * represented by the string argument in the 203 * specified radix. 204 * @throws NumberFormatException If the {@code String} does 205 * not contain a parsable {@code byte}. 206 */ valueOf(String s, int radix)207 public static Byte valueOf(String s, int radix) 208 throws NumberFormatException { 209 return valueOf(parseByte(s, radix)); 210 } 211 212 /** 213 * Returns a {@code Byte} object holding the value 214 * given by the specified {@code String}. The argument is 215 * interpreted as representing a signed decimal {@code byte}, 216 * exactly as if the argument were given to the {@link 217 * #parseByte(java.lang.String)} method. The result is a 218 * {@code Byte} object that represents the {@code byte} 219 * value specified by the string. 220 * 221 * <p> In other words, this method returns a {@code Byte} object 222 * equal to the value of: 223 * 224 * <blockquote> 225 * {@code new Byte(Byte.parseByte(s))} 226 * </blockquote> 227 * 228 * @param s the string to be parsed 229 * @return a {@code Byte} object holding the value 230 * represented by the string argument 231 * @throws NumberFormatException If the {@code String} does 232 * not contain a parsable {@code byte}. 233 */ valueOf(String s)234 public static Byte valueOf(String s) throws NumberFormatException { 235 return valueOf(s, 10); 236 } 237 238 /** 239 * Decodes a {@code String} into a {@code Byte}. 240 * Accepts decimal, hexadecimal, and octal numbers given by 241 * the following grammar: 242 * 243 * <blockquote> 244 * <dl> 245 * <dt><i>DecodableString:</i> 246 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i> 247 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i> 248 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i> 249 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i> 250 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i> 251 * 252 * <dt><i>Sign:</i> 253 * <dd>{@code -} 254 * <dd>{@code +} 255 * </dl> 256 * </blockquote> 257 * 258 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i> 259 * are as defined in section 3.10.1 of 260 * <cite>The Java™ Language Specification</cite>, 261 * except that underscores are not accepted between digits. 262 * 263 * <p>The sequence of characters following an optional 264 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}", 265 * "{@code #}", or leading zero) is parsed as by the {@code 266 * Byte.parseByte} method with the indicated radix (10, 16, or 8). 267 * This sequence of characters must represent a positive value or 268 * a {@link NumberFormatException} will be thrown. The result is 269 * negated if first character of the specified {@code String} is 270 * the minus sign. No whitespace characters are permitted in the 271 * {@code String}. 272 * 273 * @param nm the {@code String} to decode. 274 * @return a {@code Byte} object holding the {@code byte} 275 * value represented by {@code nm} 276 * @throws NumberFormatException if the {@code String} does not 277 * contain a parsable {@code byte}. 278 * @see java.lang.Byte#parseByte(java.lang.String, int) 279 */ decode(String nm)280 public static Byte decode(String nm) throws NumberFormatException { 281 int i = Integer.decode(nm); 282 if (i < MIN_VALUE || i > MAX_VALUE) 283 throw new NumberFormatException( 284 "Value " + i + " out of range from input " + nm); 285 return valueOf((byte)i); 286 } 287 288 /** 289 * The value of the {@code Byte}. 290 * 291 * @serial 292 */ 293 private final byte value; 294 295 /** 296 * Constructs a newly allocated {@code Byte} object that 297 * represents the specified {@code byte} value. 298 * 299 * @param value the value to be represented by the 300 * {@code Byte}. 301 * 302 * @deprecated 303 * It is rarely appropriate to use this constructor. The static factory 304 * {@link #valueOf(byte)} is generally a better choice, as it is 305 * likely to yield significantly better space and time performance. 306 */ 307 @Deprecated(since="9") Byte(byte value)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 * 324 * @deprecated 325 * It is rarely appropriate to use this constructor. 326 * Use {@link #parseByte(String)} to convert a string to a 327 * {@code byte} primitive, or use {@link #valueOf(String)} 328 * to convert a string to a {@code Byte} object. 329 */ 330 @Deprecated(since="9") Byte(String s)331 public Byte(String s) throws NumberFormatException { 332 this.value = parseByte(s, 10); 333 } 334 335 /** 336 * Returns the value of this {@code Byte} as a 337 * {@code byte}. 338 */ 339 @HotSpotIntrinsicCandidate byteValue()340 public byte byteValue() { 341 return value; 342 } 343 344 /** 345 * Returns the value of this {@code Byte} as a {@code short} after 346 * a widening primitive conversion. 347 * @jls 5.1.2 Widening Primitive Conversions 348 */ shortValue()349 public short shortValue() { 350 return (short)value; 351 } 352 353 /** 354 * Returns the value of this {@code Byte} as an {@code int} after 355 * a widening primitive conversion. 356 * @jls 5.1.2 Widening Primitive Conversions 357 */ intValue()358 public int intValue() { 359 return (int)value; 360 } 361 362 /** 363 * Returns the value of this {@code Byte} as a {@code long} after 364 * a widening primitive conversion. 365 * @jls 5.1.2 Widening Primitive Conversions 366 */ longValue()367 public long longValue() { 368 return (long)value; 369 } 370 371 /** 372 * Returns the value of this {@code Byte} as a {@code float} after 373 * a widening primitive conversion. 374 * @jls 5.1.2 Widening Primitive Conversions 375 */ floatValue()376 public float floatValue() { 377 return (float)value; 378 } 379 380 /** 381 * Returns the value of this {@code Byte} as a {@code double} 382 * after a widening primitive conversion. 383 * @jls 5.1.2 Widening Primitive Conversions 384 */ doubleValue()385 public double doubleValue() { 386 return (double)value; 387 } 388 389 /** 390 * Returns a {@code String} object representing this 391 * {@code Byte}'s value. The value is converted to signed 392 * decimal representation and returned as a string, exactly as if 393 * the {@code byte} value were given as an argument to the 394 * {@link java.lang.Byte#toString(byte)} method. 395 * 396 * @return a string representation of the value of this object in 397 * base 10. 398 */ toString()399 public String toString() { 400 return Integer.toString((int)value); 401 } 402 403 /** 404 * Returns a hash code for this {@code Byte}; equal to the result 405 * of invoking {@code intValue()}. 406 * 407 * @return a hash code value for this {@code Byte} 408 */ 409 @Override hashCode()410 public int hashCode() { 411 return Byte.hashCode(value); 412 } 413 414 /** 415 * Returns a hash code for a {@code byte} value; compatible with 416 * {@code Byte.hashCode()}. 417 * 418 * @param value the value to hash 419 * @return a hash code value for a {@code byte} value. 420 * @since 1.8 421 */ hashCode(byte value)422 public static int hashCode(byte value) { 423 return (int)value; 424 } 425 426 /** 427 * Compares this object to the specified object. The result is 428 * {@code true} if and only if the argument is not 429 * {@code null} and is a {@code Byte} object that 430 * contains the same {@code byte} value as this object. 431 * 432 * @param obj the object to compare with 433 * @return {@code true} if the objects are the same; 434 * {@code false} otherwise. 435 */ equals(Object obj)436 public boolean equals(Object obj) { 437 if (obj instanceof Byte) { 438 return value == ((Byte)obj).byteValue(); 439 } 440 return false; 441 } 442 443 /** 444 * Compares two {@code Byte} objects numerically. 445 * 446 * @param anotherByte the {@code Byte} to be compared. 447 * @return the value {@code 0} if this {@code Byte} is 448 * equal to the argument {@code Byte}; a value less than 449 * {@code 0} if this {@code Byte} is numerically less 450 * than the argument {@code Byte}; and a value greater than 451 * {@code 0} if this {@code Byte} is numerically 452 * greater than the argument {@code Byte} (signed 453 * comparison). 454 * @since 1.2 455 */ compareTo(Byte anotherByte)456 public int compareTo(Byte anotherByte) { 457 return compare(this.value, anotherByte.value); 458 } 459 460 /** 461 * Compares two {@code byte} values numerically. 462 * The value returned is identical to what would be returned by: 463 * <pre> 464 * Byte.valueOf(x).compareTo(Byte.valueOf(y)) 465 * </pre> 466 * 467 * @param x the first {@code byte} to compare 468 * @param y the second {@code byte} to compare 469 * @return the value {@code 0} if {@code x == y}; 470 * a value less than {@code 0} if {@code x < y}; and 471 * a value greater than {@code 0} if {@code x > y} 472 * @since 1.7 473 */ compare(byte x, byte y)474 public static int compare(byte x, byte y) { 475 return x - y; 476 } 477 478 /** 479 * Compares two {@code byte} values numerically treating the values 480 * as unsigned. 481 * 482 * @param x the first {@code byte} to compare 483 * @param y the second {@code byte} to compare 484 * @return the value {@code 0} if {@code x == y}; a value less 485 * than {@code 0} if {@code x < y} as unsigned values; and 486 * a value greater than {@code 0} if {@code x > y} as 487 * unsigned values 488 * @since 9 489 */ compareUnsigned(byte x, byte y)490 public static int compareUnsigned(byte x, byte y) { 491 return Byte.toUnsignedInt(x) - Byte.toUnsignedInt(y); 492 } 493 494 /** 495 * Converts the argument to an {@code int} by an unsigned 496 * conversion. In an unsigned conversion to an {@code int}, the 497 * high-order 24 bits of the {@code int} are zero and the 498 * low-order 8 bits are equal to the bits of the {@code byte} argument. 499 * 500 * Consequently, zero and positive {@code byte} values are mapped 501 * to a numerically equal {@code int} value and negative {@code 502 * byte} values are mapped to an {@code int} value equal to the 503 * input plus 2<sup>8</sup>. 504 * 505 * @param x the value to convert to an unsigned {@code int} 506 * @return the argument converted to {@code int} by an unsigned 507 * conversion 508 * @since 1.8 509 */ toUnsignedInt(byte x)510 public static int toUnsignedInt(byte x) { 511 return ((int) x) & 0xff; 512 } 513 514 /** 515 * Converts the argument to a {@code long} by an unsigned 516 * conversion. In an unsigned conversion to a {@code long}, the 517 * high-order 56 bits of the {@code long} are zero and the 518 * low-order 8 bits are equal to the bits of the {@code byte} argument. 519 * 520 * Consequently, zero and positive {@code byte} values are mapped 521 * to a numerically equal {@code long} value and negative {@code 522 * byte} values are mapped to a {@code long} value equal to the 523 * input plus 2<sup>8</sup>. 524 * 525 * @param x the value to convert to an unsigned {@code long} 526 * @return the argument converted to {@code long} by an unsigned 527 * conversion 528 * @since 1.8 529 */ toUnsignedLong(byte x)530 public static long toUnsignedLong(byte x) { 531 return ((long) x) & 0xffL; 532 } 533 534 535 /** 536 * The number of bits used to represent a {@code byte} value in two's 537 * complement binary form. 538 * 539 * @since 1.5 540 */ 541 public static final int SIZE = 8; 542 543 /** 544 * The number of bytes used to represent a {@code byte} value in two's 545 * complement binary form. 546 * 547 * @since 1.8 548 */ 549 public static final int BYTES = SIZE / Byte.SIZE; 550 551 /** use serialVersionUID from JDK 1.1. for interoperability */ 552 private static final long serialVersionUID = -7183698231559129828L; 553 554 // BEGIN Android-added: toHexString() for internal use. 555 /** 556 * @hide 557 */ toHexString(byte b, boolean upperCase)558 public static String toHexString(byte b, boolean upperCase) { 559 // This method currently retained because it is marked @UnsupportedAppUsage. 560 return HexEncoding.encodeToString(b, upperCase); 561 } 562 // END Android-added: toHexString() for internal use. 563 } 564