1 /* Byte.java -- object wrapper for byte 2 Copyright (C) 1998, 2001, 2002, 2005 Free Software Foundation, Inc. 3 4 This file is part of GNU Classpath. 5 6 GNU Classpath is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 GNU Classpath is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU Classpath; see the file COPYING. If not, write to the 18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19 02110-1301 USA. 20 21 Linking this library statically or dynamically with other modules is 22 making a combined work based on this library. Thus, the terms and 23 conditions of the GNU General Public License cover the whole 24 combination. 25 26 As a special exception, the copyright holders of this library give you 27 permission to link this library with independent modules to produce an 28 executable, regardless of the license terms of these independent 29 modules, and to copy and distribute the resulting executable under 30 terms of your choice, provided that you also meet, for each linked 31 independent module, the terms and conditions of the license of that 32 module. An independent module is a module which is not derived from 33 or based on this library. If you modify this library, you may extend 34 this exception to your version of the library, but you are not 35 obligated to do so. If you do not wish to do so, delete this 36 exception statement from your version. */ 37 38 39 package java.lang; 40 41 /** 42 * Instances of class <code>Byte</code> represent primitive <code>byte</code> 43 * values. 44 * 45 * Additionally, this class provides various helper functions and variables 46 * useful to bytes. 47 * 48 * @author Paul Fisher 49 * @author John Keiser 50 * @author Per Bothner 51 * @author Eric Blake (ebb9@email.byu.edu) 52 * @since 1.1 53 * @status updated to 1.5 54 */ 55 public final class Byte extends Number implements Comparable 56 { 57 /** 58 * Compatible with JDK 1.1+. 59 */ 60 private static final long serialVersionUID = -7183698231559129828L; 61 62 /** 63 * The minimum value a <code>byte</code> can represent is -128 (or 64 * -2<sup>7</sup>). 65 */ 66 public static final byte MIN_VALUE = -128; 67 68 /** 69 * The maximum value a <code>byte</code> can represent is 127 (or 70 * 2<sup>7</sup> - 1). 71 */ 72 public static final byte MAX_VALUE = 127; 73 74 /** 75 * The primitive type <code>byte</code> is represented by this 76 * <code>Class</code> object. 77 */ 78 public static final Class TYPE = VMClassLoader.getPrimitiveClass('B'); 79 80 /** 81 * The number of bits needed to represent a <code>byte</code>. 82 * @since 1.5 83 */ 84 public static final int SIZE = 8; 85 86 // This caches Byte values, and is used by boxing conversions via 87 // valueOf(). We're required to cache all possible values here. 88 private static Byte[] byteCache = new Byte[MAX_VALUE - MIN_VALUE + 1]; 89 90 /** 91 * The immutable value of this Byte. 92 * 93 * @serial the wrapped byte 94 */ 95 private final byte value; 96 97 /** 98 * Create a <code>Byte</code> object representing the value of the 99 * <code>byte</code> argument. 100 * 101 * @param value the value to use 102 */ Byte(byte value)103 public Byte(byte value) 104 { 105 this.value = value; 106 } 107 108 /** 109 * Create a <code>Byte</code> object representing the value specified 110 * by the <code>String</code> argument 111 * 112 * @param s the string to convert 113 * @throws NumberFormatException if the String does not contain a byte 114 * @see #valueOf(String) 115 */ Byte(String s)116 public Byte(String s) 117 { 118 value = parseByte(s, 10); 119 } 120 121 /** 122 * Converts the <code>byte</code> to a <code>String</code> and assumes 123 * a radix of 10. 124 * 125 * @param b the <code>byte</code> to convert to <code>String</code> 126 * @return the <code>String</code> representation of the argument 127 */ toString(byte b)128 public static String toString(byte b) 129 { 130 return String.valueOf(b); 131 } 132 133 /** 134 * Converts the specified <code>String</code> into a <code>byte</code>. 135 * This function assumes a radix of 10. 136 * 137 * @param s the <code>String</code> to convert 138 * @return the <code>byte</code> value of <code>s</code> 139 * @throws NumberFormatException if <code>s</code> cannot be parsed as a 140 * <code>byte</code> 141 * @see #parseByte(String) 142 */ parseByte(String s)143 public static byte parseByte(String s) 144 { 145 return parseByte(s, 10); 146 } 147 148 /** 149 * Converts the specified <code>String</code> into an <code>int</code> 150 * using the specified radix (base). The string must not be <code>null</code> 151 * or empty. It may begin with an optional '-', which will negate the answer, 152 * provided that there are also valid digits. Each digit is parsed as if by 153 * <code>Character.digit(d, radix)</code>, and must be in the range 154 * <code>0</code> to <code>radix - 1</code>. Finally, the result must be 155 * within <code>MIN_VALUE</code> to <code>MAX_VALUE</code>, inclusive. 156 * Unlike Double.parseDouble, you may not have a leading '+'. 157 * 158 * @param s the <code>String</code> to convert 159 * @param radix the radix (base) to use in the conversion 160 * @return the <code>String</code> argument converted to <code>byte</code> 161 * @throws NumberFormatException if <code>s</code> cannot be parsed as a 162 * <code>byte</code> 163 */ parseByte(String s, int radix)164 public static byte parseByte(String s, int radix) 165 { 166 int i = Integer.parseInt(s, radix, false); 167 if ((byte) i != i) 168 throw new NumberFormatException(); 169 return (byte) i; 170 } 171 172 /** 173 * Creates a new <code>Byte</code> object using the <code>String</code> 174 * and specified radix (base). 175 * 176 * @param s the <code>String</code> to convert 177 * @param radix the radix (base) to convert with 178 * @return the new <code>Byte</code> 179 * @throws NumberFormatException if <code>s</code> cannot be parsed as a 180 * <code>byte</code> 181 * @see #parseByte(String, int) 182 */ valueOf(String s, int radix)183 public static Byte valueOf(String s, int radix) 184 { 185 return new Byte(parseByte(s, radix)); 186 } 187 188 /** 189 * Creates a new <code>Byte</code> object using the <code>String</code>, 190 * assuming a radix of 10. 191 * 192 * @param s the <code>String</code> to convert 193 * @return the new <code>Byte</code> 194 * @throws NumberFormatException if <code>s</code> cannot be parsed as a 195 * <code>byte</code> 196 * @see #Byte(String) 197 * @see #parseByte(String) 198 */ valueOf(String s)199 public static Byte valueOf(String s) 200 { 201 return new Byte(parseByte(s, 10)); 202 } 203 204 /** 205 * Returns a <code>Byte</code> object wrapping the value. 206 * In contrast to the <code>Byte</code> constructor, this method 207 * will cache some values. It is used by boxing conversion. 208 * 209 * @param val the value to wrap 210 * @return the <code>Byte</code> 211 * 212 * @since 1.5 213 */ valueOf(byte val)214 public static Byte valueOf(byte val) 215 { 216 synchronized (byteCache) 217 { 218 if (byteCache[val - MIN_VALUE] == null) 219 byteCache[val - MIN_VALUE] = new Byte(val); 220 return byteCache[val - MIN_VALUE]; 221 } 222 } 223 224 /** 225 * Convert the specified <code>String</code> into a <code>Byte</code>. 226 * The <code>String</code> may represent decimal, hexadecimal, or 227 * octal numbers. 228 * 229 * <p>The extended BNF grammar is as follows:<br> 230 * <pre> 231 * <em>DecodableString</em>: 232 * ( [ <code>-</code> ] <em>DecimalNumber</em> ) 233 * | ( [ <code>-</code> ] ( <code>0x</code> | <code>0X</code> 234 * | <code>#</code> ) { <em>HexDigit</em> }+ ) 235 * | ( [ <code>-</code> ] <code>0</code> { <em>OctalDigit</em> } ) 236 * <em>DecimalNumber</em>: 237 * <em>DecimalDigit except '0'</em> { <em>DecimalDigit</em> } 238 * <em>DecimalDigit</em>: 239 * <em>Character.digit(d, 10) has value 0 to 9</em> 240 * <em>OctalDigit</em>: 241 * <em>Character.digit(d, 8) has value 0 to 7</em> 242 * <em>DecimalDigit</em>: 243 * <em>Character.digit(d, 16) has value 0 to 15</em> 244 * </pre> 245 * Finally, the value must be in the range <code>MIN_VALUE</code> to 246 * <code>MAX_VALUE</code>, or an exception is thrown. 247 * 248 * @param s the <code>String</code> to interpret 249 * @return the value of the String as a <code>Byte</code> 250 * @throws NumberFormatException if <code>s</code> cannot be parsed as a 251 * <code>byte</code> 252 * @throws NullPointerException if <code>s</code> is null 253 * @see Integer#decode(String) 254 */ decode(String s)255 public static Byte decode(String s) 256 { 257 int i = Integer.parseInt(s, 10, true); 258 if ((byte) i != i) 259 throw new NumberFormatException(); 260 return new Byte((byte) i); 261 } 262 263 /** 264 * Return the value of this <code>Byte</code>. 265 * 266 * @return the byte value 267 */ byteValue()268 public byte byteValue() 269 { 270 return value; 271 } 272 273 /** 274 * Return the value of this <code>Byte</code> as a <code>short</code>. 275 * 276 * @return the short value 277 */ shortValue()278 public short shortValue() 279 { 280 return value; 281 } 282 283 /** 284 * Return the value of this <code>Byte</code> as an <code>int</code>. 285 * 286 * @return the int value 287 */ intValue()288 public int intValue() 289 { 290 return value; 291 } 292 293 /** 294 * Return the value of this <code>Byte</code> as a <code>long</code>. 295 * 296 * @return the long value 297 */ longValue()298 public long longValue() 299 { 300 return value; 301 } 302 303 /** 304 * Return the value of this <code>Byte</code> as a <code>float</code>. 305 * 306 * @return the float value 307 */ floatValue()308 public float floatValue() 309 { 310 return value; 311 } 312 313 /** 314 * Return the value of this <code>Byte</code> as a <code>double</code>. 315 * 316 * @return the double value 317 */ doubleValue()318 public double doubleValue() 319 { 320 return value; 321 } 322 323 /** 324 * Converts the <code>Byte</code> value to a <code>String</code> and 325 * assumes a radix of 10. 326 * 327 * @return the <code>String</code> representation of this <code>Byte</code> 328 * @see Integer#toString() 329 */ toString()330 public String toString() 331 { 332 return String.valueOf(value); 333 } 334 335 /** 336 * Return a hashcode representing this Object. <code>Byte</code>'s hash 337 * code is simply its value. 338 * 339 * @return this Object's hash code 340 */ hashCode()341 public int hashCode() 342 { 343 return value; 344 } 345 346 /** 347 * Returns <code>true</code> if <code>obj</code> is an instance of 348 * <code>Byte</code> and represents the same byte value. 349 * 350 * @param obj the object to compare 351 * @return whether these Objects are semantically equal 352 */ equals(Object obj)353 public boolean equals(Object obj) 354 { 355 return obj instanceof Byte && value == ((Byte) obj).value; 356 } 357 358 /** 359 * Compare two Bytes numerically by comparing their <code>byte</code> values. 360 * The result is positive if the first is greater, negative if the second 361 * is greater, and 0 if the two are equal. 362 * 363 * @param b the Byte to compare 364 * @return the comparison 365 * @since 1.2 366 */ compareTo(Byte b)367 public int compareTo(Byte b) 368 { 369 return value - b.value; 370 } 371 372 /** 373 * Behaves like <code>compareTo(Byte)</code> unless the Object 374 * is not a <code>Byte</code>. 375 * 376 * @param o the object to compare 377 * @return the comparison 378 * @throws ClassCastException if the argument is not a <code>Byte</code> 379 * @see #compareTo(Byte) 380 * @see Comparable 381 * @since 1.2 382 */ compareTo(Object o)383 public int compareTo(Object o) 384 { 385 return compareTo((Byte) o); 386 } 387 } 388