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 libcore.util.HexEncoding; 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 JDK1.1 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 * Returns a new {@code String} object representing the 69 * specified {@code byte}. The radix is assumed to be 10. 70 * 71 * @param b the {@code byte} to be converted 72 * @return the string representation of the specified {@code byte} 73 * @see java.lang.Integer#toString(int) 74 */ toString(byte b)75 public static String toString(byte b) { 76 return Integer.toString((int)b, 10); 77 } 78 79 private static class ByteCache { ByteCache()80 private ByteCache(){} 81 82 static final Byte cache[] = new Byte[-(-128) + 127 + 1]; 83 84 static { 85 for(int i = 0; i < cache.length; i++) 86 cache[i] = new Byte((byte)(i - 128)); 87 } 88 } 89 90 /** 91 * Returns a {@code Byte} instance representing the specified 92 * {@code byte} value. 93 * If a new {@code Byte} instance is not required, this method 94 * should generally be used in preference to the constructor 95 * {@link #Byte(byte)}, as this method is likely to yield 96 * significantly better space and time performance since 97 * all byte values are cached. 98 * 99 * @param b a byte value. 100 * @return a {@code Byte} instance representing {@code b}. 101 * @since 1.5 102 */ valueOf(byte b)103 public static Byte valueOf(byte b) { 104 final int offset = 128; 105 return ByteCache.cache[(int)b + offset]; 106 } 107 108 /** 109 * Parses the string argument as a signed {@code byte} in the 110 * radix specified by the second argument. The characters in the 111 * string must all be digits, of the specified radix (as 112 * determined by whether {@link java.lang.Character#digit(char, 113 * int)} returns a nonnegative value) except that the first 114 * character may be an ASCII minus sign {@code '-'} 115 * ({@code '\u005Cu002D'}) to indicate a negative value or an 116 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to 117 * indicate a positive value. The resulting {@code byte} value is 118 * returned. 119 * 120 * <p>An exception of type {@code NumberFormatException} is 121 * thrown if any of the following situations occurs: 122 * <ul> 123 * <li> The first argument is {@code null} or is a string of 124 * length zero. 125 * 126 * <li> The radix is either smaller than {@link 127 * java.lang.Character#MIN_RADIX} or larger than {@link 128 * java.lang.Character#MAX_RADIX}. 129 * 130 * <li> Any character of the string is not a digit of the 131 * specified radix, except that the first character may be a minus 132 * sign {@code '-'} ({@code '\u005Cu002D'}) or plus sign 133 * {@code '+'} ({@code '\u005Cu002B'}) provided that the 134 * string is longer than length 1. 135 * 136 * <li> The value represented by the string is not a value of type 137 * {@code byte}. 138 * </ul> 139 * 140 * @param s the {@code String} containing the 141 * {@code byte} 142 * representation to be parsed 143 * @param radix the radix to be used while parsing {@code s} 144 * @return the {@code byte} value represented by the string 145 * argument in the specified radix 146 * @throws NumberFormatException If the string does 147 * not contain a parsable {@code byte}. 148 */ parseByte(String s, int radix)149 public static byte parseByte(String s, int radix) 150 throws NumberFormatException { 151 int i = Integer.parseInt(s, radix); 152 if (i < MIN_VALUE || i > MAX_VALUE) 153 throw new NumberFormatException( 154 "Value out of range. Value:\"" + s + "\" Radix:" + radix); 155 return (byte)i; 156 } 157 158 /** 159 * Parses the string argument as a signed decimal {@code 160 * byte}. The characters in the string must all be decimal digits, 161 * except that the first character may be an ASCII minus sign 162 * {@code '-'} ({@code '\u005Cu002D'}) to indicate a negative 163 * value or an ASCII plus sign {@code '+'} 164 * ({@code '\u005Cu002B'}) to indicate a positive value. The 165 * resulting {@code byte} value is returned, exactly as if the 166 * argument and the radix 10 were given as arguments to the {@link 167 * #parseByte(java.lang.String, int)} method. 168 * 169 * @param s a {@code String} containing the 170 * {@code byte} representation to be parsed 171 * @return the {@code byte} value represented by the 172 * argument in decimal 173 * @throws NumberFormatException if the string does not 174 * contain a parsable {@code byte}. 175 */ parseByte(String s)176 public static byte parseByte(String s) throws NumberFormatException { 177 return parseByte(s, 10); 178 } 179 180 /** 181 * Returns a {@code Byte} object holding the value 182 * extracted from the specified {@code String} when parsed 183 * with the radix given by the second argument. The first argument 184 * is interpreted as representing a signed {@code byte} in 185 * the radix specified by the second argument, exactly as if the 186 * argument were given to the {@link #parseByte(java.lang.String, 187 * int)} method. The result is a {@code Byte} object that 188 * represents the {@code byte} value specified by the string. 189 * 190 * <p> In other words, this method returns a {@code Byte} object 191 * equal to the value of: 192 * 193 * <blockquote> 194 * {@code new Byte(Byte.parseByte(s, radix))} 195 * </blockquote> 196 * 197 * @param s the string to be parsed 198 * @param radix the radix to be used in interpreting {@code s} 199 * @return a {@code Byte} object holding the value 200 * represented by the string argument in the 201 * specified radix. 202 * @throws NumberFormatException If the {@code String} does 203 * not contain a parsable {@code byte}. 204 */ valueOf(String s, int radix)205 public static Byte valueOf(String s, int radix) 206 throws NumberFormatException { 207 return valueOf(parseByte(s, radix)); 208 } 209 210 /** 211 * Returns a {@code Byte} object holding the value 212 * given by the specified {@code String}. The argument is 213 * interpreted as representing a signed decimal {@code byte}, 214 * exactly as if the argument were given to the {@link 215 * #parseByte(java.lang.String)} method. The result is a 216 * {@code Byte} object that represents the {@code byte} 217 * value specified by the string. 218 * 219 * <p> In other words, this method returns a {@code Byte} object 220 * equal to the value of: 221 * 222 * <blockquote> 223 * {@code new Byte(Byte.parseByte(s))} 224 * </blockquote> 225 * 226 * @param s the string to be parsed 227 * @return a {@code Byte} object holding the value 228 * represented by the string argument 229 * @throws NumberFormatException If the {@code String} does 230 * not contain a parsable {@code byte}. 231 */ valueOf(String s)232 public static Byte valueOf(String s) throws NumberFormatException { 233 return valueOf(s, 10); 234 } 235 236 /** 237 * Decodes a {@code String} into a {@code Byte}. 238 * Accepts decimal, hexadecimal, and octal numbers given by 239 * the following grammar: 240 * 241 * <blockquote> 242 * <dl> 243 * <dt><i>DecodableString:</i> 244 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i> 245 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i> 246 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i> 247 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i> 248 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i> 249 * 250 * <dt><i>Sign:</i> 251 * <dd>{@code -} 252 * <dd>{@code +} 253 * </dl> 254 * </blockquote> 255 * 256 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i> 257 * are as defined in section 3.10.1 of 258 * <cite>The Java™ Language Specification</cite>, 259 * except that underscores are not accepted between digits. 260 * 261 * <p>The sequence of characters following an optional 262 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}", 263 * "{@code #}", or leading zero) is parsed as by the {@code 264 * Byte.parseByte} method with the indicated radix (10, 16, or 8). 265 * This sequence of characters must represent a positive value or 266 * a {@link NumberFormatException} will be thrown. The result is 267 * negated if first character of the specified {@code String} is 268 * the minus sign. No whitespace characters are permitted in the 269 * {@code String}. 270 * 271 * @param nm the {@code String} to decode. 272 * @return a {@code Byte} object holding the {@code byte} 273 * value represented by {@code nm} 274 * @throws NumberFormatException if the {@code String} does not 275 * contain a parsable {@code byte}. 276 * @see java.lang.Byte#parseByte(java.lang.String, int) 277 */ decode(String nm)278 public static Byte decode(String nm) throws NumberFormatException { 279 int i = Integer.decode(nm); 280 if (i < MIN_VALUE || i > MAX_VALUE) 281 throw new NumberFormatException( 282 "Value " + i + " out of range from input " + nm); 283 return valueOf((byte)i); 284 } 285 286 /** 287 * The value of the {@code Byte}. 288 * 289 * @serial 290 */ 291 private final byte value; 292 293 /** 294 * Constructs a newly allocated {@code Byte} object that 295 * represents the specified {@code byte} value. 296 * 297 * @param value the value to be represented by the 298 * {@code Byte}. 299 */ Byte(byte value)300 public Byte(byte value) { 301 this.value = value; 302 } 303 304 /** 305 * Constructs a newly allocated {@code Byte} object that 306 * represents the {@code byte} value indicated by the 307 * {@code String} parameter. The string is converted to a 308 * {@code byte} value in exactly the manner used by the 309 * {@code parseByte} method for radix 10. 310 * 311 * @param s the {@code String} to be converted to a 312 * {@code Byte} 313 * @throws NumberFormatException If the {@code String} 314 * does not contain a parsable {@code byte}. 315 * @see java.lang.Byte#parseByte(java.lang.String, int) 316 */ Byte(String s)317 public Byte(String s) throws NumberFormatException { 318 this.value = parseByte(s, 10); 319 } 320 321 /** 322 * Returns the value of this {@code Byte} as a 323 * {@code byte}. 324 */ byteValue()325 public byte byteValue() { 326 return value; 327 } 328 329 /** 330 * Returns the value of this {@code Byte} as a {@code short} after 331 * a widening primitive conversion. 332 * @jls 5.1.2 Widening Primitive Conversions 333 */ shortValue()334 public short shortValue() { 335 return (short)value; 336 } 337 338 /** 339 * Returns the value of this {@code Byte} as an {@code int} after 340 * a widening primitive conversion. 341 * @jls 5.1.2 Widening Primitive Conversions 342 */ intValue()343 public int intValue() { 344 return (int)value; 345 } 346 347 /** 348 * Returns the value of this {@code Byte} as a {@code long} after 349 * a widening primitive conversion. 350 * @jls 5.1.2 Widening Primitive Conversions 351 */ longValue()352 public long longValue() { 353 return (long)value; 354 } 355 356 /** 357 * Returns the value of this {@code Byte} as a {@code float} after 358 * a widening primitive conversion. 359 * @jls 5.1.2 Widening Primitive Conversions 360 */ floatValue()361 public float floatValue() { 362 return (float)value; 363 } 364 365 /** 366 * Returns the value of this {@code Byte} as a {@code double} 367 * after a widening primitive conversion. 368 * @jls 5.1.2 Widening Primitive Conversions 369 */ doubleValue()370 public double doubleValue() { 371 return (double)value; 372 } 373 374 /** 375 * Returns a {@code String} object representing this 376 * {@code Byte}'s value. The value is converted to signed 377 * decimal representation and returned as a string, exactly as if 378 * the {@code byte} value were given as an argument to the 379 * {@link java.lang.Byte#toString(byte)} method. 380 * 381 * @return a string representation of the value of this object in 382 * base 10. 383 */ toString()384 public String toString() { 385 return Integer.toString((int)value); 386 } 387 388 /** 389 * Returns a hash code for this {@code Byte}; equal to the result 390 * of invoking {@code intValue()}. 391 * 392 * @return a hash code value for this {@code Byte} 393 */ 394 @Override hashCode()395 public int hashCode() { 396 return Byte.hashCode(value); 397 } 398 399 /** 400 * Returns a hash code for a {@code byte} value; compatible with 401 * {@code Byte.hashCode()}. 402 * 403 * @param value the value to hash 404 * @return a hash code value for a {@code byte} value. 405 * @since 1.8 406 */ hashCode(byte value)407 public static int hashCode(byte value) { 408 return (int)value; 409 } 410 411 /** 412 * Compares this object to the specified object. The result is 413 * {@code true} if and only if the argument is not 414 * {@code null} and is a {@code Byte} object that 415 * contains the same {@code byte} value as this object. 416 * 417 * @param obj the object to compare with 418 * @return {@code true} if the objects are the same; 419 * {@code false} otherwise. 420 */ equals(Object obj)421 public boolean equals(Object obj) { 422 if (obj instanceof Byte) { 423 return value == ((Byte)obj).byteValue(); 424 } 425 return false; 426 } 427 428 /** 429 * Compares two {@code Byte} objects numerically. 430 * 431 * @param anotherByte the {@code Byte} to be compared. 432 * @return the value {@code 0} if this {@code Byte} is 433 * equal to the argument {@code Byte}; a value less than 434 * {@code 0} if this {@code Byte} is numerically less 435 * than the argument {@code Byte}; and a value greater than 436 * {@code 0} if this {@code Byte} is numerically 437 * greater than the argument {@code Byte} (signed 438 * comparison). 439 * @since 1.2 440 */ compareTo(Byte anotherByte)441 public int compareTo(Byte anotherByte) { 442 return compare(this.value, anotherByte.value); 443 } 444 445 /** 446 * Compares two {@code byte} values numerically. 447 * The value returned is identical to what would be returned by: 448 * <pre> 449 * Byte.valueOf(x).compareTo(Byte.valueOf(y)) 450 * </pre> 451 * 452 * @param x the first {@code byte} to compare 453 * @param y the second {@code byte} to compare 454 * @return the value {@code 0} if {@code x == y}; 455 * a value less than {@code 0} if {@code x < y}; and 456 * a value greater than {@code 0} if {@code x > y} 457 * @since 1.7 458 */ compare(byte x, byte y)459 public static int compare(byte x, byte y) { 460 return x - y; 461 } 462 463 /** 464 * Converts the argument to an {@code int} by an unsigned 465 * conversion. In an unsigned conversion to an {@code int}, the 466 * high-order 24 bits of the {@code int} are zero and the 467 * low-order 8 bits are equal to the bits of the {@code byte} argument. 468 * 469 * Consequently, zero and positive {@code byte} values are mapped 470 * to a numerically equal {@code int} value and negative {@code 471 * byte} values are mapped to an {@code int} value equal to the 472 * input plus 2<sup>8</sup>. 473 * 474 * @param x the value to convert to an unsigned {@code int} 475 * @return the argument converted to {@code int} by an unsigned 476 * conversion 477 * @since 1.8 478 */ toUnsignedInt(byte x)479 public static int toUnsignedInt(byte x) { 480 return ((int) x) & 0xff; 481 } 482 483 /** 484 * Converts the argument to a {@code long} by an unsigned 485 * conversion. In an unsigned conversion to a {@code long}, the 486 * high-order 56 bits of the {@code long} are zero and the 487 * low-order 8 bits are equal to the bits of the {@code byte} argument. 488 * 489 * Consequently, zero and positive {@code byte} values are mapped 490 * to a numerically equal {@code long} value and negative {@code 491 * byte} values are mapped to a {@code long} value equal to the 492 * input plus 2<sup>8</sup>. 493 * 494 * @param x the value to convert to an unsigned {@code long} 495 * @return the argument converted to {@code long} by an unsigned 496 * conversion 497 * @since 1.8 498 */ toUnsignedLong(byte x)499 public static long toUnsignedLong(byte x) { 500 return ((long) x) & 0xffL; 501 } 502 503 504 /** 505 * The number of bits used to represent a {@code byte} value in two's 506 * complement binary form. 507 * 508 * @since 1.5 509 */ 510 public static final int SIZE = 8; 511 512 /** 513 * The number of bytes used to represent a {@code byte} value in two's 514 * complement binary form. 515 * 516 * @since 1.8 517 */ 518 public static final int BYTES = SIZE / Byte.SIZE; 519 520 /** use serialVersionUID from JDK 1.1. for interoperability */ 521 private static final long serialVersionUID = -7183698231559129828L; 522 523 // BEGIN Android-added: toHexString() for internal use. 524 /** 525 * @hide 526 */ toHexString(byte b, boolean upperCase)527 public static String toHexString(byte b, boolean upperCase) { 528 // This method currently retained because it is marked @UnsupportedAppUsage. 529 return HexEncoding.encodeToString(b, upperCase); 530 } 531 // END Android-added: toHexString() for internal use. 532 } 533