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