J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1996-2006 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package java.lang; |
| 27 | |
| 28 | /** |
| 29 | * |
| 30 | * The {@code Byte} class wraps a value of primitive type {@code byte} |
| 31 | * in an object. An object of type {@code Byte} contains a single |
| 32 | * field whose type is {@code byte}. |
| 33 | * |
| 34 | * <p>In addition, this class provides several methods for converting |
| 35 | * a {@code byte} to a {@code String} and a {@code String} to a {@code |
| 36 | * byte}, as well as other constants and methods useful when dealing |
| 37 | * with a {@code byte}. |
| 38 | * |
| 39 | * @author Nakul Saraiya |
| 40 | * @author Joseph D. Darcy |
| 41 | * @see java.lang.Number |
| 42 | * @since JDK1.1 |
| 43 | */ |
| 44 | public final class Byte extends Number implements Comparable<Byte> { |
| 45 | |
| 46 | /** |
| 47 | * A constant holding the minimum value a {@code byte} can |
| 48 | * have, -2<sup>7</sup>. |
| 49 | */ |
| 50 | public static final byte MIN_VALUE = -128; |
| 51 | |
| 52 | /** |
| 53 | * A constant holding the maximum value a {@code byte} can |
| 54 | * have, 2<sup>7</sup>-1. |
| 55 | */ |
| 56 | public static final byte MAX_VALUE = 127; |
| 57 | |
| 58 | /** |
| 59 | * The {@code Class} instance representing the primitive type |
| 60 | * {@code byte}. |
| 61 | */ |
| 62 | public static final Class<Byte> TYPE = (Class<Byte>) Class.getPrimitiveClass("byte"); |
| 63 | |
| 64 | /** |
| 65 | * Returns a new {@code String} object representing the |
| 66 | * specified {@code byte}. The radix is assumed to be 10. |
| 67 | * |
| 68 | * @param b the {@code byte} to be converted |
| 69 | * @return the string representation of the specified {@code byte} |
| 70 | * @see java.lang.Integer#toString(int) |
| 71 | */ |
| 72 | public static String toString(byte b) { |
| 73 | return Integer.toString((int)b, 10); |
| 74 | } |
| 75 | |
| 76 | private static class ByteCache { |
| 77 | private ByteCache(){} |
| 78 | |
| 79 | static final Byte cache[] = new Byte[-(-128) + 127 + 1]; |
| 80 | |
| 81 | static { |
| 82 | for(int i = 0; i < cache.length; i++) |
| 83 | cache[i] = new Byte((byte)(i - 128)); |
| 84 | } |
| 85 | } |
| 86 | |
| 87 | /** |
| 88 | * Returns a {@code Byte} instance representing the specified |
| 89 | * {@code byte} value. |
| 90 | * If a new {@code Byte} instance is not required, this method |
| 91 | * should generally be used in preference to the constructor |
| 92 | * {@link #Byte(byte)}, as this method is likely to yield |
| 93 | * significantly better space and time performance by caching |
| 94 | * frequently requested values. |
| 95 | * |
| 96 | * @param b a byte value. |
| 97 | * @return a {@code Byte} instance representing {@code b}. |
| 98 | * @since 1.5 |
| 99 | */ |
| 100 | public static Byte valueOf(byte b) { |
| 101 | final int offset = 128; |
| 102 | return ByteCache.cache[(int)b + offset]; |
| 103 | } |
| 104 | |
| 105 | /** |
| 106 | * Parses the string argument as a signed {@code byte} in the |
| 107 | * radix specified by the second argument. The characters in the |
| 108 | * string must all be digits, of the specified radix (as |
| 109 | * determined by whether {@link java.lang.Character#digit(char, |
| 110 | * int)} returns a nonnegative value) except that the first |
| 111 | * character may be an ASCII minus sign {@code '-'} |
| 112 | * (<code>'\u002D'</code>) to indicate a negative value or an |
| 113 | * ASCII plus sign {@code '+'} (<code>'\u002B'</code>) to |
| 114 | * indicate a positive value. The resulting {@code byte} value is |
| 115 | * returned. |
| 116 | * |
| 117 | * <p>An exception of type {@code NumberFormatException} is |
| 118 | * thrown if any of the following situations occurs: |
| 119 | * <ul> |
| 120 | * <li> The first argument is {@code null} or is a string of |
| 121 | * length zero. |
| 122 | * |
| 123 | * <li> The radix is either smaller than {@link |
| 124 | * java.lang.Character#MIN_RADIX} or larger than {@link |
| 125 | * java.lang.Character#MAX_RADIX}. |
| 126 | * |
| 127 | * <li> Any character of the string is not a digit of the |
| 128 | * specified radix, except that the first character may be a minus |
| 129 | * sign {@code '-'} (<code>'\u002D'</code>) or plus sign |
| 130 | * {@code '+'} (<code>'\u002B'</code>) provided that the |
| 131 | * string is longer than length 1. |
| 132 | * |
| 133 | * <li> The value represented by the string is not a value of type |
| 134 | * {@code byte}. |
| 135 | * </ul> |
| 136 | * |
| 137 | * @param s the {@code String} containing the |
| 138 | * {@code byte} |
| 139 | * representation to be parsed |
| 140 | * @param radix the radix to be used while parsing {@code s} |
| 141 | * @return the {@code byte} value represented by the string |
| 142 | * argument in the specified radix |
| 143 | * @throws NumberFormatException If the string does |
| 144 | * not contain a parsable {@code byte}. |
| 145 | */ |
| 146 | public static byte parseByte(String s, int radix) |
| 147 | throws NumberFormatException { |
| 148 | int i = Integer.parseInt(s, radix); |
| 149 | if (i < MIN_VALUE || i > MAX_VALUE) |
| 150 | throw new NumberFormatException( |
| 151 | "Value out of range. Value:\"" + s + "\" Radix:" + radix); |
| 152 | return (byte)i; |
| 153 | } |
| 154 | |
| 155 | /** |
| 156 | * Parses the string argument as a signed decimal {@code |
| 157 | * byte}. The characters in the string must all be decimal digits, |
| 158 | * except that the first character may be an ASCII minus sign |
| 159 | * {@code '-'} (<code>'\u002D'</code>) to indicate a negative |
| 160 | * value or an ASCII plus sign {@code '+'} |
| 161 | * (<code>'\u002B'</code>) to indicate a positive value. The |
| 162 | * resulting {@code byte} value is returned, exactly as if the |
| 163 | * argument and the radix 10 were given as arguments to the {@link |
| 164 | * #parseByte(java.lang.String, int)} method. |
| 165 | * |
| 166 | * @param s a {@code String} containing the |
| 167 | * {@code byte} representation to be parsed |
| 168 | * @return the {@code byte} value represented by the |
| 169 | * argument in decimal |
| 170 | * @throws NumberFormatException if the string does not |
| 171 | * contain a parsable {@code byte}. |
| 172 | */ |
| 173 | public static byte parseByte(String s) throws NumberFormatException { |
| 174 | return parseByte(s, 10); |
| 175 | } |
| 176 | |
| 177 | /** |
| 178 | * Returns a {@code Byte} object holding the value |
| 179 | * extracted from the specified {@code String} when parsed |
| 180 | * with the radix given by the second argument. The first argument |
| 181 | * is interpreted as representing a signed {@code byte} in |
| 182 | * the radix specified by the second argument, exactly as if the |
| 183 | * argument were given to the {@link #parseByte(java.lang.String, |
| 184 | * int)} method. The result is a {@code Byte} object that |
| 185 | * represents the {@code byte} value specified by the string. |
| 186 | * |
| 187 | * <p> In other words, this method returns a {@code Byte} object |
| 188 | * equal to the value of: |
| 189 | * |
| 190 | * <blockquote> |
| 191 | * {@code new Byte(Byte.parseByte(s, radix))} |
| 192 | * </blockquote> |
| 193 | * |
| 194 | * @param s the string to be parsed |
| 195 | * @param radix the radix to be used in interpreting {@code s} |
| 196 | * @return a {@code Byte} object holding the value |
| 197 | * represented by the string argument in the |
| 198 | * specified radix. |
| 199 | * @throws NumberFormatException If the {@code String} does |
| 200 | * not contain a parsable {@code byte}. |
| 201 | */ |
| 202 | public static Byte valueOf(String s, int radix) |
| 203 | throws NumberFormatException { |
| 204 | return new Byte(parseByte(s, radix)); |
| 205 | } |
| 206 | |
| 207 | /** |
| 208 | * Returns a {@code Byte} object holding the value |
| 209 | * given by the specified {@code String}. The argument is |
| 210 | * interpreted as representing a signed decimal {@code byte}, |
| 211 | * exactly as if the argument were given to the {@link |
| 212 | * #parseByte(java.lang.String)} method. The result is a |
| 213 | * {@code Byte} object that represents the {@code byte} |
| 214 | * value specified by the string. |
| 215 | * |
| 216 | * <p> In other words, this method returns a {@code Byte} object |
| 217 | * equal to the value of: |
| 218 | * |
| 219 | * <blockquote> |
| 220 | * {@code new Byte(Byte.parseByte(s))} |
| 221 | * </blockquote> |
| 222 | * |
| 223 | * @param s the string to be parsed |
| 224 | * @return a {@code Byte} object holding the value |
| 225 | * represented by the string argument |
| 226 | * @throws NumberFormatException If the {@code String} does |
| 227 | * not contain a parsable {@code byte}. |
| 228 | */ |
| 229 | public static Byte valueOf(String s) throws NumberFormatException { |
| 230 | return valueOf(s, 10); |
| 231 | } |
| 232 | |
| 233 | /** |
| 234 | * Decodes a {@code String} into a {@code Byte}. |
| 235 | * Accepts decimal, hexadecimal, and octal numbers given by |
| 236 | * the following grammar: |
| 237 | * |
| 238 | * <blockquote> |
| 239 | * <dl> |
| 240 | * <dt><i>DecodableString:</i> |
| 241 | * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i> |
| 242 | * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i> |
| 243 | * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i> |
| 244 | * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i> |
| 245 | * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i> |
| 246 | * <p> |
| 247 | * <dt><i>Sign:</i> |
| 248 | * <dd>{@code -} |
| 249 | * <dd>{@code +} |
| 250 | * </dl> |
| 251 | * </blockquote> |
| 252 | * |
| 253 | * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i> |
| 254 | * are defined in <a href="http://java.sun.com/docs/books/jls/second_edition/html/lexical.doc.html#48282">§3.10.1</a> |
| 255 | * of the <a href="http://java.sun.com/docs/books/jls/html/">Java |
| 256 | * Language Specification</a>. |
| 257 | * |
| 258 | * <p>The sequence of characters following an optional |
| 259 | * sign and/or radix specifier ("{@code 0x}", "{@code 0X}", |
| 260 | * "{@code #}", or leading zero) is parsed as by the {@code |
| 261 | * Byte.parseByte} method with the indicated radix (10, 16, or 8). |
| 262 | * This sequence of characters must represent a positive value or |
| 263 | * a {@link NumberFormatException} will be thrown. The result is |
| 264 | * negated if first character of the specified {@code String} is |
| 265 | * the minus sign. No whitespace characters are permitted in the |
| 266 | * {@code String}. |
| 267 | * |
| 268 | * @param nm the {@code String} to decode. |
| 269 | * @return a {@code Byte} object holding the {@code byte} |
| 270 | * value represented by {@code nm} |
| 271 | * @throws NumberFormatException if the {@code String} does not |
| 272 | * contain a parsable {@code byte}. |
| 273 | * @see java.lang.Byte#parseByte(java.lang.String, int) |
| 274 | */ |
| 275 | public static Byte decode(String nm) throws NumberFormatException { |
| 276 | int i = Integer.decode(nm); |
| 277 | if (i < MIN_VALUE || i > MAX_VALUE) |
| 278 | throw new NumberFormatException( |
| 279 | "Value " + i + " out of range from input " + nm); |
| 280 | return (byte)i; |
| 281 | } |
| 282 | |
| 283 | /** |
| 284 | * The value of the {@code Byte}. |
| 285 | * |
| 286 | * @serial |
| 287 | */ |
| 288 | private final byte value; |
| 289 | |
| 290 | /** |
| 291 | * Constructs a newly allocated {@code Byte} object that |
| 292 | * represents the specified {@code byte} value. |
| 293 | * |
| 294 | * @param value the value to be represented by the |
| 295 | * {@code Byte}. |
| 296 | */ |
| 297 | public Byte(byte value) { |
| 298 | this.value = value; |
| 299 | } |
| 300 | |
| 301 | /** |
| 302 | * Constructs a newly allocated {@code Byte} object that |
| 303 | * represents the {@code byte} value indicated by the |
| 304 | * {@code String} parameter. The string is converted to a |
| 305 | * {@code byte} value in exactly the manner used by the |
| 306 | * {@code parseByte} method for radix 10. |
| 307 | * |
| 308 | * @param s the {@code String} to be converted to a |
| 309 | * {@code Byte} |
| 310 | * @throws NumberFormatException If the {@code String} |
| 311 | * does not contain a parsable {@code byte}. |
| 312 | * @see java.lang.Byte#parseByte(java.lang.String, int) |
| 313 | */ |
| 314 | public Byte(String s) throws NumberFormatException { |
| 315 | this.value = parseByte(s, 10); |
| 316 | } |
| 317 | |
| 318 | /** |
| 319 | * Returns the value of this {@code Byte} as a |
| 320 | * {@code byte}. |
| 321 | */ |
| 322 | public byte byteValue() { |
| 323 | return value; |
| 324 | } |
| 325 | |
| 326 | /** |
| 327 | * Returns the value of this {@code Byte} as a |
| 328 | * {@code short}. |
| 329 | */ |
| 330 | public short shortValue() { |
| 331 | return (short)value; |
| 332 | } |
| 333 | |
| 334 | /** |
| 335 | * Returns the value of this {@code Byte} as an |
| 336 | * {@code int}. |
| 337 | */ |
| 338 | public int intValue() { |
| 339 | return (int)value; |
| 340 | } |
| 341 | |
| 342 | /** |
| 343 | * Returns the value of this {@code Byte} as a |
| 344 | * {@code long}. |
| 345 | */ |
| 346 | public long longValue() { |
| 347 | return (long)value; |
| 348 | } |
| 349 | |
| 350 | /** |
| 351 | * Returns the value of this {@code Byte} as a |
| 352 | * {@code float}. |
| 353 | */ |
| 354 | public float floatValue() { |
| 355 | return (float)value; |
| 356 | } |
| 357 | |
| 358 | /** |
| 359 | * Returns the value of this {@code Byte} as a |
| 360 | * {@code double}. |
| 361 | */ |
| 362 | public double doubleValue() { |
| 363 | return (double)value; |
| 364 | } |
| 365 | |
| 366 | /** |
| 367 | * Returns a {@code String} object representing this |
| 368 | * {@code Byte}'s value. The value is converted to signed |
| 369 | * decimal representation and returned as a string, exactly as if |
| 370 | * the {@code byte} value were given as an argument to the |
| 371 | * {@link java.lang.Byte#toString(byte)} method. |
| 372 | * |
| 373 | * @return a string representation of the value of this object in |
| 374 | * base 10. |
| 375 | */ |
| 376 | public String toString() { |
| 377 | return String.valueOf((int)value); |
| 378 | } |
| 379 | |
| 380 | /** |
| 381 | * Returns a hash code for this {@code Byte}. |
| 382 | */ |
| 383 | public int hashCode() { |
| 384 | return (int)value; |
| 385 | } |
| 386 | |
| 387 | /** |
| 388 | * Compares this object to the specified object. The result is |
| 389 | * {@code true} if and only if the argument is not |
| 390 | * {@code null} and is a {@code Byte} object that |
| 391 | * contains the same {@code byte} value as this object. |
| 392 | * |
| 393 | * @param obj the object to compare with |
| 394 | * @return {@code true} if the objects are the same; |
| 395 | * {@code false} otherwise. |
| 396 | */ |
| 397 | public boolean equals(Object obj) { |
| 398 | if (obj instanceof Byte) { |
| 399 | return value == ((Byte)obj).byteValue(); |
| 400 | } |
| 401 | return false; |
| 402 | } |
| 403 | |
| 404 | /** |
| 405 | * Compares two {@code Byte} objects numerically. |
| 406 | * |
| 407 | * @param anotherByte the {@code Byte} to be compared. |
| 408 | * @return the value {@code 0} if this {@code Byte} is |
| 409 | * equal to the argument {@code Byte}; a value less than |
| 410 | * {@code 0} if this {@code Byte} is numerically less |
| 411 | * than the argument {@code Byte}; and a value greater than |
| 412 | * {@code 0} if this {@code Byte} is numerically |
| 413 | * greater than the argument {@code Byte} (signed |
| 414 | * comparison). |
| 415 | * @since 1.2 |
| 416 | */ |
| 417 | public int compareTo(Byte anotherByte) { |
| 418 | return this.value - anotherByte.value; |
| 419 | } |
| 420 | |
| 421 | /** |
| 422 | * The number of bits used to represent a {@code byte} value in two's |
| 423 | * complement binary form. |
| 424 | * |
| 425 | * @since 1.5 |
| 426 | */ |
| 427 | public static final int SIZE = 8; |
| 428 | |
| 429 | /** use serialVersionUID from JDK 1.1. for interoperability */ |
| 430 | private static final long serialVersionUID = -7183698231559129828L; |
| 431 | } |