1 /*
2 * Copyright (c) 1996, 2020, 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 jdk.internal.misc.VM;
30
31 import java.lang.constant.Constable;
32 import java.lang.constant.DynamicConstantDesc;
33 import java.util.Optional;
34
35 import static java.lang.constant.ConstantDescs.BSM_EXPLICIT_CAST;
36 import static java.lang.constant.ConstantDescs.CD_byte;
37 import static java.lang.constant.ConstantDescs.CD_int;
38 import static java.lang.constant.ConstantDescs.DEFAULT_NAME;
39
40 /**
41 *
42 * The {@code Byte} class wraps a value of primitive type {@code byte}
43 * in an object. An object of type {@code Byte} contains a single
44 * field whose type is {@code byte}.
45 *
46 * <p>In addition, this class provides several methods for converting
47 * a {@code byte} to a {@code String} and a {@code String} to a {@code
48 * byte}, as well as other constants and methods useful when dealing
49 * with a {@code byte}.
50 *
51 * @author Nakul Saraiya
52 * @author Joseph D. Darcy
53 * @see java.lang.Number
54 * @since 1.1
55 */
56 public final class Byte extends Number implements Comparable<Byte>, Constable {
57
58 /**
59 * A constant holding the minimum value a {@code byte} can
60 * have, -2<sup>7</sup>.
61 */
62 public static final byte MIN_VALUE = -128;
63
64 /**
65 * A constant holding the maximum value a {@code byte} can
66 * have, 2<sup>7</sup>-1.
67 */
68 public static final byte MAX_VALUE = 127;
69
70 /**
71 * The {@code Class} instance representing the primitive type
72 * {@code byte}.
73 */
74 @SuppressWarnings("unchecked")
75 public static final Class<Byte> TYPE = (Class<Byte>) Class.getPrimitiveClass("byte");
76
77 /**
78 * Returns a new {@code String} object representing the
79 * specified {@code byte}. The radix is assumed to be 10.
80 *
81 * @param b the {@code byte} to be converted
82 * @return the string representation of the specified {@code byte}
83 * @see java.lang.Integer#toString(int)
84 */
85 public static String toString(byte b) {
86 return Integer.toString((int)b, 10);
87 }
88
89 /**
90 * Returns an {@link Optional} containing the nominal descriptor for this
91 * instance.
92 *
93 * @return an {@link Optional} describing the {@linkplain Byte} instance
94 * @since 15
95 */
96 @Override
97 public Optional<DynamicConstantDesc<Byte>> describeConstable() {
98 return Optional.of(DynamicConstantDesc.ofNamed(BSM_EXPLICIT_CAST, DEFAULT_NAME, CD_byte, intValue()));
99 }
100
101 private static class ByteCache {
102 private ByteCache() {}
103
104 static final Byte[] cache;
105 static Byte[] archivedCache;
106
107 static {
108 final int size = -(-128) + 127 + 1;
109
110 // Load and use the archived cache if it exists
111 VM.initializeFromArchive(ByteCache.class);
112 if (archivedCache == null || archivedCache.length != size) {
113 Byte[] c = new Byte[size];
114 byte value = (byte)-128;
115 for(int i = 0; i < size; i++) {
116 c[i] = new Byte(value++);
117 }
118 archivedCache = c;
119 }
120 cache = archivedCache;
121 }
122 }
123
124 /**
125 * Returns a {@code Byte} instance representing the specified
126 * {@code byte} value.
127 * If a new {@code Byte} instance is not required, this method
128 * should generally be used in preference to the constructor
129 * {@link #Byte(byte)}, as this method is likely to yield
130 * significantly better space and time performance since
131 * all byte values are cached.
132 *
133 * @param b a byte value.
134 * @return a {@code Byte} instance representing {@code b}.
135 * @since 1.5
136 */
137 @HotSpotIntrinsicCandidate
138 public static Byte valueOf(byte b) {
139 final int offset = 128;
140 return ByteCache.cache[(int)b + offset];
141 }
142
143 /**
144 * Parses the string argument as a signed {@code byte} in the
145 * radix specified by the second argument. The characters in the
146 * string must all be digits, of the specified radix (as
147 * determined by whether {@link java.lang.Character#digit(char,
148 * int)} returns a nonnegative value) except that the first
149 * character may be an ASCII minus sign {@code '-'}
150 * ({@code '\u005Cu002D'}) to indicate a negative value or an
151 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to
152 * indicate a positive value. The resulting {@code byte} value is
153 * returned.
154 *
155 * <p>An exception of type {@code NumberFormatException} is
156 * thrown if any of the following situations occurs:
157 * <ul>
158 * <li> The first argument is {@code null} or is a string of
159 * length zero.
160 *
161 * <li> The radix is either smaller than {@link
162 * java.lang.Character#MIN_RADIX} or larger than {@link
163 * java.lang.Character#MAX_RADIX}.
164 *
165 * <li> Any character of the string is not a digit of the
166 * specified radix, except that the first character may be a minus
167 * sign {@code '-'} ({@code '\u005Cu002D'}) or plus sign
168 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
169 * string is longer than length 1.
170 *
171 * <li> The value represented by the string is not a value of type
172 * {@code byte}.
173 * </ul>
174 *
175 * @param s the {@code String} containing the
176 * {@code byte}
177 * representation to be parsed
178 * @param radix the radix to be used while parsing {@code s}
179 * @return the {@code byte} value represented by the string
180 * argument in the specified radix
181 * @throws NumberFormatException If the string does
182 * not contain a parsable {@code byte}.
183 */
184 public static byte parseByte(String s, int radix)
185 throws NumberFormatException {
186 int i = Integer.parseInt(s, radix);
187 if (i < MIN_VALUE || i > MAX_VALUE)
188 throw new NumberFormatException(
189 "Value out of range. Value:\"" + s + "\" Radix:" + radix);
190 return (byte)i;
191 }
192
193 /**
194 * Parses the string argument as a signed decimal {@code
195 * byte}. The characters in the string must all be decimal digits,
196 * except that the first character may be an ASCII minus sign
197 * {@code '-'} ({@code '\u005Cu002D'}) to indicate a negative
198 * value or an ASCII plus sign {@code '+'}
199 * ({@code '\u005Cu002B'}) to indicate a positive value. The
200 * resulting {@code byte} value is returned, exactly as if the
201 * argument and the radix 10 were given as arguments to the {@link
202 * #parseByte(java.lang.String, int)} method.
203 *
204 * @param s a {@code String} containing the
205 * {@code byte} representation to be parsed
206 * @return the {@code byte} value represented by the
207 * argument in decimal
208 * @throws NumberFormatException if the string does not
209 * contain a parsable {@code byte}.
210 */
211 public static byte parseByte(String s) throws NumberFormatException {
212 return parseByte(s, 10);
213 }
214
215 /**
216 * Returns a {@code Byte} object holding the value
217 * extracted from the specified {@code String} when parsed
218 * with the radix given by the second argument. The first argument
219 * is interpreted as representing a signed {@code byte} in
220 * the radix specified by the second argument, exactly as if the
221 * argument were given to the {@link #parseByte(java.lang.String,
222 * int)} method. The result is a {@code Byte} object that
223 * represents the {@code byte} value specified by the string.
224 *
225 * <p> In other words, this method returns a {@code Byte} object
226 * equal to the value of:
227 *
228 * <blockquote>
229 * {@code new Byte(Byte.parseByte(s, radix))}
230 * </blockquote>
231 *
232 * @param s the string to be parsed
233 * @param radix the radix to be used in interpreting {@code s}
234 * @return a {@code Byte} object holding the value
235 * represented by the string argument in the
236 * specified radix.
237 * @throws NumberFormatException If the {@code String} does
238 * not contain a parsable {@code byte}.
239 */
240 public static Byte valueOf(String s, int radix)
241 throws NumberFormatException {
242 return valueOf(parseByte(s, radix));
243 }
244
245 /**
246 * Returns a {@code Byte} object holding the value
247 * given by the specified {@code String}. The argument is
248 * interpreted as representing a signed decimal {@code byte},
249 * exactly as if the argument were given to the {@link
250 * #parseByte(java.lang.String)} method. The result is a
251 * {@code Byte} object that represents the {@code byte}
252 * value specified by the string.
253 *
254 * <p> In other words, this method returns a {@code Byte} object
255 * equal to the value of:
256 *
257 * <blockquote>
258 * {@code new Byte(Byte.parseByte(s))}
259 * </blockquote>
260 *
261 * @param s the string to be parsed
262 * @return a {@code Byte} object holding the value
263 * represented by the string argument
264 * @throws NumberFormatException If the {@code String} does
265 * not contain a parsable {@code byte}.
266 */
267 public static Byte valueOf(String s) throws NumberFormatException {
268 return valueOf(s, 10);
269 }
270
271 /**
272 * Decodes a {@code String} into a {@code Byte}.
273 * Accepts decimal, hexadecimal, and octal numbers given by
274 * the following grammar:
275 *
276 * <blockquote>
277 * <dl>
278 * <dt><i>DecodableString:</i>
279 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
280 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
281 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
282 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
283 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
284 *
285 * <dt><i>Sign:</i>
286 * <dd>{@code -}
287 * <dd>{@code +}
288 * </dl>
289 * </blockquote>
290 *
291 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
292 * are as defined in section 3.10.1 of
293 * <cite>The Java Language Specification</cite>,
294 * except that underscores are not accepted between digits.
295 *
296 * <p>The sequence of characters following an optional
297 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
298 * "{@code #}", or leading zero) is parsed as by the {@code
299 * Byte.parseByte} method with the indicated radix (10, 16, or 8).
300 * This sequence of characters must represent a positive value or
301 * a {@link NumberFormatException} will be thrown. The result is
302 * negated if first character of the specified {@code String} is
303 * the minus sign. No whitespace characters are permitted in the
304 * {@code String}.
305 *
306 * @param nm the {@code String} to decode.
307 * @return a {@code Byte} object holding the {@code byte}
308 * value represented by {@code nm}
309 * @throws NumberFormatException if the {@code String} does not
310 * contain a parsable {@code byte}.
311 * @see java.lang.Byte#parseByte(java.lang.String, int)
312 */
313 public static Byte decode(String nm) throws NumberFormatException {
314 int i = Integer.decode(nm);
315 if (i < MIN_VALUE || i > MAX_VALUE)
316 throw new NumberFormatException(
317 "Value " + i + " out of range from input " + nm);
318 return valueOf((byte)i);
319 }
320
321 /**
322 * The value of the {@code Byte}.
323 *
324 * @serial
325 */
326 private final byte value;
327
328 /**
329 * Constructs a newly allocated {@code Byte} object that
330 * represents the specified {@code byte} value.
331 *
332 * @param value the value to be represented by the
333 * {@code Byte}.
334 *
335 * @deprecated
336 * It is rarely appropriate to use this constructor. The static factory
337 * {@link #valueOf(byte)} is generally a better choice, as it is
338 * likely to yield significantly better space and time performance.
339 */
340 @Deprecated(since="9")
341 public Byte(byte value) {
342 this.value = value;
343 }
344
345 /**
346 * Constructs a newly allocated {@code Byte} object that
347 * represents the {@code byte} value indicated by the
348 * {@code String} parameter. The string is converted to a
349 * {@code byte} value in exactly the manner used by the
350 * {@code parseByte} method for radix 10.
351 *
352 * @param s the {@code String} to be converted to a
353 * {@code Byte}
354 * @throws NumberFormatException if the {@code String}
355 * does not contain a parsable {@code byte}.
356 *
357 * @deprecated
358 * It is rarely appropriate to use this constructor.
359 * Use {@link #parseByte(String)} to convert a string to a
360 * {@code byte} primitive, or use {@link #valueOf(String)}
361 * to convert a string to a {@code Byte} object.
362 */
363 @Deprecated(since="9")
364 public Byte(String s) throws NumberFormatException {
365 this.value = parseByte(s, 10);
366 }
367
368 /**
369 * Returns the value of this {@code Byte} as a
370 * {@code byte}.
371 */
372 @HotSpotIntrinsicCandidate
373 public byte byteValue() {
374 return value;
375 }
376
377 /**
378 * Returns the value of this {@code Byte} as a {@code short} after
379 * a widening primitive conversion.
380 * @jls 5.1.2 Widening Primitive Conversion
381 */
382 public short shortValue() {
383 return (short)value;
384 }
385
386 /**
387 * Returns the value of this {@code Byte} as an {@code int} after
388 * a widening primitive conversion.
389 * @jls 5.1.2 Widening Primitive Conversion
390 */
391 public int intValue() {
392 return (int)value;
393 }
394
395 /**
396 * Returns the value of this {@code Byte} as a {@code long} after
397 * a widening primitive conversion.
398 * @jls 5.1.2 Widening Primitive Conversion
399 */
400 public long longValue() {
401 return (long)value;
402 }
403
404 /**
405 * Returns the value of this {@code Byte} as a {@code float} after
406 * a widening primitive conversion.
407 * @jls 5.1.2 Widening Primitive Conversion
408 */
409 public float floatValue() {
410 return (float)value;
411 }
412
413 /**
414 * Returns the value of this {@code Byte} as a {@code double}
415 * after a widening primitive conversion.
416 * @jls 5.1.2 Widening Primitive Conversion
417 */
418 public double doubleValue() {
419 return (double)value;
420 }
421
422 /**
423 * Returns a {@code String} object representing this
424 * {@code Byte}'s value. The value is converted to signed
425 * decimal representation and returned as a string, exactly as if
426 * the {@code byte} value were given as an argument to the
427 * {@link java.lang.Byte#toString(byte)} method.
428 *
429 * @return a string representation of the value of this object in
430 * base 10.
431 */
432 public String toString() {
433 return Integer.toString((int)value);
434 }
435
436 /**
437 * Returns a hash code for this {@code Byte}; equal to the result
438 * of invoking {@code intValue()}.
439 *
440 * @return a hash code value for this {@code Byte}
441 */
442 @Override
443 public int hashCode() {
444 return Byte.hashCode(value);
445 }
446
447 /**
448 * Returns a hash code for a {@code byte} value; compatible with
449 * {@code Byte.hashCode()}.
450 *
451 * @param value the value to hash
452 * @return a hash code value for a {@code byte} value.
453 * @since 1.8
454 */
455 public static int hashCode(byte value) {
456 return (int)value;
457 }
458
459 /**
460 * Compares this object to the specified object. The result is
461 * {@code true} if and only if the argument is not
462 * {@code null} and is a {@code Byte} object that
463 * contains the same {@code byte} value as this object.
464 *
465 * @param obj the object to compare with
466 * @return {@code true} if the objects are the same;
467 * {@code false} otherwise.
468 */
469 public boolean equals(Object obj) {
470 if (obj instanceof Byte) {
471 return value == ((Byte)obj).byteValue();
472 }
473 return false;
474 }
475
476 /**
477 * Compares two {@code Byte} objects numerically.
478 *
479 * @param anotherByte the {@code Byte} to be compared.
480 * @return the value {@code 0} if this {@code Byte} is
481 * equal to the argument {@code Byte}; a value less than
482 * {@code 0} if this {@code Byte} is numerically less
483 * than the argument {@code Byte}; and a value greater than
484 * {@code 0} if this {@code Byte} is numerically
485 * greater than the argument {@code Byte} (signed
486 * comparison).
487 * @since 1.2
488 */
489 public int compareTo(Byte anotherByte) {
490 return compare(this.value, anotherByte.value);
491 }
492
493 /**
494 * Compares two {@code byte} values numerically.
495 * The value returned is identical to what would be returned by:
496 * <pre>
497 * Byte.valueOf(x).compareTo(Byte.valueOf(y))
498 * </pre>
499 *
500 * @param x the first {@code byte} to compare
501 * @param y the second {@code byte} to compare
502 * @return the value {@code 0} if {@code x == y};
503 * a value less than {@code 0} if {@code x < y}; and
504 * a value greater than {@code 0} if {@code x > y}
505 * @since 1.7
506 */
507 public static int compare(byte x, byte y) {
508 return x - y;
509 }
510
511 /**
512 * Compares two {@code byte} values numerically treating the values
513 * as unsigned.
514 *
515 * @param x the first {@code byte} to compare
516 * @param y the second {@code byte} to compare
517 * @return the value {@code 0} if {@code x == y}; a value less
518 * than {@code 0} if {@code x < y} as unsigned values; and
519 * a value greater than {@code 0} if {@code x > y} as
520 * unsigned values
521 * @since 9
522 */
523 public static int compareUnsigned(byte x, byte y) {
524 return Byte.toUnsignedInt(x) - Byte.toUnsignedInt(y);
525 }
526
527 /**
528 * Converts the argument to an {@code int} by an unsigned
529 * conversion. In an unsigned conversion to an {@code int}, the
530 * high-order 24 bits of the {@code int} are zero and the
531 * low-order 8 bits are equal to the bits of the {@code byte} argument.
532 *
533 * Consequently, zero and positive {@code byte} values are mapped
534 * to a numerically equal {@code int} value and negative {@code
535 * byte} values are mapped to an {@code int} value equal to the
536 * input plus 2<sup>8</sup>.
537 *
538 * @param x the value to convert to an unsigned {@code int}
539 * @return the argument converted to {@code int} by an unsigned
540 * conversion
541 * @since 1.8
542 */
543 public static int toUnsignedInt(byte x) {
544 return ((int) x) & 0xff;
545 }
546
547 /**
548 * Converts the argument to a {@code long} by an unsigned
549 * conversion. In an unsigned conversion to a {@code long}, the
550 * high-order 56 bits of the {@code long} are zero and the
551 * low-order 8 bits are equal to the bits of the {@code byte} argument.
552 *
553 * Consequently, zero and positive {@code byte} values are mapped
554 * to a numerically equal {@code long} value and negative {@code
555 * byte} values are mapped to a {@code long} value equal to the
556 * input plus 2<sup>8</sup>.
557 *
558 * @param x the value to convert to an unsigned {@code long}
559 * @return the argument converted to {@code long} by an unsigned
560 * conversion
561 * @since 1.8
562 */
563 public static long toUnsignedLong(byte x) {
564 return ((long) x) & 0xffL;
565 }
566
567
568 /**
569 * The number of bits used to represent a {@code byte} value in two's
570 * complement binary form.
571 *
572 * @since 1.5
573 */
574 public static final int SIZE = 8;
575
576 /**
577 * The number of bytes used to represent a {@code byte} value in two's
578 * complement binary form.
579 *
580 * @since 1.8
581 */
582 public static final int BYTES = SIZE / Byte.SIZE;
583
584 /** use serialVersionUID from JDK 1.1. for interoperability */
585 @java.io.Serial
586 private static final long serialVersionUID = -7183698231559129828L;
587 }