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 }