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25 
26 package java.lang;
27 
28 import java.lang.annotation.Native;
29 import java.lang.invoke.MethodHandles;
30 import java.lang.constant.Constable;
31 import java.lang.constant.ConstantDesc;
32 import java.math.*;
33 import java.util.Objects;
34 import java.util.Optional;
35 
36 import jdk.internal.misc.CDS;
37 import jdk.internal.vm.annotation.IntrinsicCandidate;
38 
39 import static java.lang.String.COMPACT_STRINGS;
40 import static java.lang.String.LATIN1;
41 import static java.lang.String.UTF16;
42 
43 /**
44  * The {@code Long} class wraps a value of the primitive type {@code
45  * long} in an object. An object of type {@code Long} contains a
46  * single field whose type is {@code long}.
47  *
48  * <p> In addition, this class provides several methods for converting
49  * a {@code long} to a {@code String} and a {@code String} to a {@code
50  * long}, as well as other constants and methods useful when dealing
51  * with a {@code long}.
52  *
53  * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
54  * class; programmers should treat instances that are
55  * {@linkplain #equals(Object) equal} as interchangeable and should not
56  * use instances for synchronization, or unpredictable behavior may
57  * occur. For example, in a future release, synchronization may fail.
58  *
59  * <p>Implementation note: The implementations of the "bit twiddling"
60  * methods (such as {@link #highestOneBit(long) highestOneBit} and
61  * {@link #numberOfTrailingZeros(long) numberOfTrailingZeros}) are
62  * based on material from Henry S. Warren, Jr.'s <i>Hacker's
63  * Delight</i>, (Addison Wesley, 2002).
64  *
65  * @author  Lee Boynton
66  * @author  Arthur van Hoff
67  * @author  Josh Bloch
68  * @author  Joseph D. Darcy
69  * @since   1.0
70  */
71 @jdk.internal.ValueBased
72 public final class Long extends Number
73         implements Comparable<Long>, Constable, ConstantDesc {
74     /**
75      * A constant holding the minimum value a {@code long} can
76      * have, -2<sup>63</sup>.
77      */
78     @Native public static final long MIN_VALUE = 0x8000000000000000L;
79 
80     /**
81      * A constant holding the maximum value a {@code long} can
82      * have, 2<sup>63</sup>-1.
83      */
84     @Native public static final long MAX_VALUE = 0x7fffffffffffffffL;
85 
86     /**
87      * The {@code Class} instance representing the primitive type
88      * {@code long}.
89      *
90      * @since   1.1
91      */
92     @SuppressWarnings("unchecked")
93     public static final Class<Long>     TYPE = (Class<Long>) Class.getPrimitiveClass("long");
94 
95     /**
96      * Returns a string representation of the first argument in the
97      * radix specified by the second argument.
98      *
99      * <p>If the radix is smaller than {@code Character.MIN_RADIX}
100      * or larger than {@code Character.MAX_RADIX}, then the radix
101      * {@code 10} is used instead.
102      *
103      * <p>If the first argument is negative, the first element of the
104      * result is the ASCII minus sign {@code '-'}
105      * ({@code '\u005Cu002d'}). If the first argument is not
106      * negative, no sign character appears in the result.
107      *
108      * <p>The remaining characters of the result represent the magnitude
109      * of the first argument. If the magnitude is zero, it is
110      * represented by a single zero character {@code '0'}
111      * ({@code '\u005Cu0030'}); otherwise, the first character of
112      * the representation of the magnitude will not be the zero
113      * character.  The following ASCII characters are used as digits:
114      *
115      * <blockquote>
116      *   {@code 0123456789abcdefghijklmnopqrstuvwxyz}
117      * </blockquote>
118      *
119      * These are {@code '\u005Cu0030'} through
120      * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
121      * {@code '\u005Cu007a'}. If {@code radix} is
122      * <var>N</var>, then the first <var>N</var> of these characters
123      * are used as radix-<var>N</var> digits in the order shown. Thus,
124      * the digits for hexadecimal (radix 16) are
125      * {@code 0123456789abcdef}. If uppercase letters are
126      * desired, the {@link java.lang.String#toUpperCase()} method may
127      * be called on the result:
128      *
129      * <blockquote>
130      *  {@code Long.toString(n, 16).toUpperCase()}
131      * </blockquote>
132      *
133      * @param   i       a {@code long} to be converted to a string.
134      * @param   radix   the radix to use in the string representation.
135      * @return  a string representation of the argument in the specified radix.
136      * @see     java.lang.Character#MAX_RADIX
137      * @see     java.lang.Character#MIN_RADIX
138      */
toString(long i, int radix)139     public static String toString(long i, int radix) {
140         if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
141             radix = 10;
142         if (radix == 10)
143             return toString(i);
144 
145         if (COMPACT_STRINGS) {
146             byte[] buf = new byte[65];
147             int charPos = 64;
148             boolean negative = (i < 0);
149 
150             if (!negative) {
151                 i = -i;
152             }
153 
154             while (i <= -radix) {
155                 buf[charPos--] = (byte)Integer.digits[(int)(-(i % radix))];
156                 i = i / radix;
157             }
158             buf[charPos] = (byte)Integer.digits[(int)(-i)];
159 
160             if (negative) {
161                 buf[--charPos] = '-';
162             }
163             return StringLatin1.newString(buf, charPos, (65 - charPos));
164         }
165         return toStringUTF16(i, radix);
166     }
167 
toStringUTF16(long i, int radix)168     private static String toStringUTF16(long i, int radix) {
169         byte[] buf = new byte[65 * 2];
170         int charPos = 64;
171         boolean negative = (i < 0);
172         if (!negative) {
173             i = -i;
174         }
175         while (i <= -radix) {
176             StringUTF16.putChar(buf, charPos--, Integer.digits[(int)(-(i % radix))]);
177             i = i / radix;
178         }
179         StringUTF16.putChar(buf, charPos, Integer.digits[(int)(-i)]);
180         if (negative) {
181             StringUTF16.putChar(buf, --charPos, '-');
182         }
183         return StringUTF16.newString(buf, charPos, (65 - charPos));
184     }
185 
186     /**
187      * Returns a string representation of the first argument as an
188      * unsigned integer value in the radix specified by the second
189      * argument.
190      *
191      * <p>If the radix is smaller than {@code Character.MIN_RADIX}
192      * or larger than {@code Character.MAX_RADIX}, then the radix
193      * {@code 10} is used instead.
194      *
195      * <p>Note that since the first argument is treated as an unsigned
196      * value, no leading sign character is printed.
197      *
198      * <p>If the magnitude is zero, it is represented by a single zero
199      * character {@code '0'} ({@code '\u005Cu0030'}); otherwise,
200      * the first character of the representation of the magnitude will
201      * not be the zero character.
202      *
203      * <p>The behavior of radixes and the characters used as digits
204      * are the same as {@link #toString(long, int) toString}.
205      *
206      * @param   i       an integer to be converted to an unsigned string.
207      * @param   radix   the radix to use in the string representation.
208      * @return  an unsigned string representation of the argument in the specified radix.
209      * @see     #toString(long, int)
210      * @since 1.8
211      */
toUnsignedString(long i, int radix)212     public static String toUnsignedString(long i, int radix) {
213         if (i >= 0)
214             return toString(i, radix);
215         else {
216             return switch (radix) {
217                 case 2  -> toBinaryString(i);
218                 case 4  -> toUnsignedString0(i, 2);
219                 case 8  -> toOctalString(i);
220                 case 10 -> {
221                     /*
222                      * We can get the effect of an unsigned division by 10
223                      * on a long value by first shifting right, yielding a
224                      * positive value, and then dividing by 5.  This
225                      * allows the last digit and preceding digits to be
226                      * isolated more quickly than by an initial conversion
227                      * to BigInteger.
228                      */
229                     long quot = (i >>> 1) / 5;
230                     long rem = i - quot * 10;
231                     yield toString(quot) + rem;
232                 }
233                 case 16 -> toHexString(i);
234                 case 32 -> toUnsignedString0(i, 5);
235                 default -> toUnsignedBigInteger(i).toString(radix);
236             };
237         }
238     }
239 
240     /**
241      * Return a BigInteger equal to the unsigned value of the
242      * argument.
243      */
toUnsignedBigInteger(long i)244     private static BigInteger toUnsignedBigInteger(long i) {
245         if (i >= 0L)
246             return BigInteger.valueOf(i);
247         else {
248             int upper = (int) (i >>> 32);
249             int lower = (int) i;
250 
251             // return (upper << 32) + lower
252             return (BigInteger.valueOf(Integer.toUnsignedLong(upper))).shiftLeft(32).
253                 add(BigInteger.valueOf(Integer.toUnsignedLong(lower)));
254         }
255     }
256 
257     /**
258      * Returns a string representation of the {@code long}
259      * argument as an unsigned integer in base&nbsp;16.
260      *
261      * <p>The unsigned {@code long} value is the argument plus
262      * 2<sup>64</sup> if the argument is negative; otherwise, it is
263      * equal to the argument.  This value is converted to a string of
264      * ASCII digits in hexadecimal (base&nbsp;16) with no extra
265      * leading {@code 0}s.
266      *
267      * <p>The value of the argument can be recovered from the returned
268      * string {@code s} by calling {@link
269      * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
270      * 16)}.
271      *
272      * <p>If the unsigned magnitude is zero, it is represented by a
273      * single zero character {@code '0'} ({@code '\u005Cu0030'});
274      * otherwise, the first character of the representation of the
275      * unsigned magnitude will not be the zero character. The
276      * following characters are used as hexadecimal digits:
277      *
278      * <blockquote>
279      *  {@code 0123456789abcdef}
280      * </blockquote>
281      *
282      * These are the characters {@code '\u005Cu0030'} through
283      * {@code '\u005Cu0039'} and  {@code '\u005Cu0061'} through
284      * {@code '\u005Cu0066'}.  If uppercase letters are desired,
285      * the {@link java.lang.String#toUpperCase()} method may be called
286      * on the result:
287      *
288      * <blockquote>
289      *  {@code Long.toHexString(n).toUpperCase()}
290      * </blockquote>
291      *
292      * @apiNote
293      * The {@link java.util.HexFormat} class provides formatting and parsing
294      * of byte arrays and primitives to return a string or adding to an {@link Appendable}.
295      * {@code HexFormat} formats and parses uppercase or lowercase hexadecimal characters,
296      * with leading zeros and for byte arrays includes for each byte
297      * a delimiter, prefix, and suffix.
298      *
299      * @param   i   a {@code long} to be converted to a string.
300      * @return  the string representation of the unsigned {@code long}
301      *          value represented by the argument in hexadecimal
302      *          (base&nbsp;16).
303      * @see java.util.HexFormat
304      * @see #parseUnsignedLong(String, int)
305      * @see #toUnsignedString(long, int)
306      * @since   1.0.2
307      */
toHexString(long i)308     public static String toHexString(long i) {
309         return toUnsignedString0(i, 4);
310     }
311 
312     /**
313      * Returns a string representation of the {@code long}
314      * argument as an unsigned integer in base&nbsp;8.
315      *
316      * <p>The unsigned {@code long} value is the argument plus
317      * 2<sup>64</sup> if the argument is negative; otherwise, it is
318      * equal to the argument.  This value is converted to a string of
319      * ASCII digits in octal (base&nbsp;8) with no extra leading
320      * {@code 0}s.
321      *
322      * <p>The value of the argument can be recovered from the returned
323      * string {@code s} by calling {@link
324      * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
325      * 8)}.
326      *
327      * <p>If the unsigned magnitude is zero, it is represented by a
328      * single zero character {@code '0'} ({@code '\u005Cu0030'});
329      * otherwise, the first character of the representation of the
330      * unsigned magnitude will not be the zero character. The
331      * following characters are used as octal digits:
332      *
333      * <blockquote>
334      *  {@code 01234567}
335      * </blockquote>
336      *
337      * These are the characters {@code '\u005Cu0030'} through
338      * {@code '\u005Cu0037'}.
339      *
340      * @param   i   a {@code long} to be converted to a string.
341      * @return  the string representation of the unsigned {@code long}
342      *          value represented by the argument in octal (base&nbsp;8).
343      * @see #parseUnsignedLong(String, int)
344      * @see #toUnsignedString(long, int)
345      * @since   1.0.2
346      */
toOctalString(long i)347     public static String toOctalString(long i) {
348         return toUnsignedString0(i, 3);
349     }
350 
351     /**
352      * Returns a string representation of the {@code long}
353      * argument as an unsigned integer in base&nbsp;2.
354      *
355      * <p>The unsigned {@code long} value is the argument plus
356      * 2<sup>64</sup> if the argument is negative; otherwise, it is
357      * equal to the argument.  This value is converted to a string of
358      * ASCII digits in binary (base&nbsp;2) with no extra leading
359      * {@code 0}s.
360      *
361      * <p>The value of the argument can be recovered from the returned
362      * string {@code s} by calling {@link
363      * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
364      * 2)}.
365      *
366      * <p>If the unsigned magnitude is zero, it is represented by a
367      * single zero character {@code '0'} ({@code '\u005Cu0030'});
368      * otherwise, the first character of the representation of the
369      * unsigned magnitude will not be the zero character. The
370      * characters {@code '0'} ({@code '\u005Cu0030'}) and {@code
371      * '1'} ({@code '\u005Cu0031'}) are used as binary digits.
372      *
373      * @param   i   a {@code long} to be converted to a string.
374      * @return  the string representation of the unsigned {@code long}
375      *          value represented by the argument in binary (base&nbsp;2).
376      * @see #parseUnsignedLong(String, int)
377      * @see #toUnsignedString(long, int)
378      * @since   1.0.2
379      */
toBinaryString(long i)380     public static String toBinaryString(long i) {
381         return toUnsignedString0(i, 1);
382     }
383 
384     /**
385      * Format a long (treated as unsigned) into a String.
386      * @param val the value to format
387      * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
388      */
toUnsignedString0(long val, int shift)389     static String toUnsignedString0(long val, int shift) {
390         // assert shift > 0 && shift <=5 : "Illegal shift value";
391         int mag = Long.SIZE - Long.numberOfLeadingZeros(val);
392         int chars = Math.max(((mag + (shift - 1)) / shift), 1);
393         if (COMPACT_STRINGS) {
394             byte[] buf = new byte[chars];
395             formatUnsignedLong0(val, shift, buf, 0, chars);
396             return new String(buf, LATIN1);
397         } else {
398             byte[] buf = new byte[chars * 2];
399             formatUnsignedLong0UTF16(val, shift, buf, 0, chars);
400             return new String(buf, UTF16);
401         }
402     }
403 
404     /**
405      * Format a long (treated as unsigned) into a byte buffer (LATIN1 version). If
406      * {@code len} exceeds the formatted ASCII representation of {@code val},
407      * {@code buf} will be padded with leading zeroes.
408      *
409      * @param val the unsigned long to format
410      * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
411      * @param buf the byte buffer to write to
412      * @param offset the offset in the destination buffer to start at
413      * @param len the number of characters to write
414      */
formatUnsignedLong0(long val, int shift, byte[] buf, int offset, int len)415     private static void formatUnsignedLong0(long val, int shift, byte[] buf, int offset, int len) {
416         int charPos = offset + len;
417         int radix = 1 << shift;
418         int mask = radix - 1;
419         do {
420             buf[--charPos] = (byte)Integer.digits[((int) val) & mask];
421             val >>>= shift;
422         } while (charPos > offset);
423     }
424 
425     /**
426      * Format a long (treated as unsigned) into a byte buffer (UTF16 version). If
427      * {@code len} exceeds the formatted ASCII representation of {@code val},
428      * {@code buf} will be padded with leading zeroes.
429      *
430      * @param val the unsigned long to format
431      * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
432      * @param buf the byte buffer to write to
433      * @param offset the offset in the destination buffer to start at
434      * @param len the number of characters to write
435      */
formatUnsignedLong0UTF16(long val, int shift, byte[] buf, int offset, int len)436     private static void formatUnsignedLong0UTF16(long val, int shift, byte[] buf, int offset, int len) {
437         int charPos = offset + len;
438         int radix = 1 << shift;
439         int mask = radix - 1;
440         do {
441             StringUTF16.putChar(buf, --charPos, Integer.digits[((int) val) & mask]);
442             val >>>= shift;
443         } while (charPos > offset);
444     }
445 
fastUUID(long lsb, long msb)446     static String fastUUID(long lsb, long msb) {
447         if (COMPACT_STRINGS) {
448             byte[] buf = new byte[36];
449             formatUnsignedLong0(lsb,        4, buf, 24, 12);
450             formatUnsignedLong0(lsb >>> 48, 4, buf, 19, 4);
451             formatUnsignedLong0(msb,        4, buf, 14, 4);
452             formatUnsignedLong0(msb >>> 16, 4, buf, 9,  4);
453             formatUnsignedLong0(msb >>> 32, 4, buf, 0,  8);
454 
455             buf[23] = '-';
456             buf[18] = '-';
457             buf[13] = '-';
458             buf[8]  = '-';
459 
460             return new String(buf, LATIN1);
461         } else {
462             byte[] buf = new byte[72];
463 
464             formatUnsignedLong0UTF16(lsb,        4, buf, 24, 12);
465             formatUnsignedLong0UTF16(lsb >>> 48, 4, buf, 19, 4);
466             formatUnsignedLong0UTF16(msb,        4, buf, 14, 4);
467             formatUnsignedLong0UTF16(msb >>> 16, 4, buf, 9,  4);
468             formatUnsignedLong0UTF16(msb >>> 32, 4, buf, 0,  8);
469 
470             StringUTF16.putChar(buf, 23, '-');
471             StringUTF16.putChar(buf, 18, '-');
472             StringUTF16.putChar(buf, 13, '-');
473             StringUTF16.putChar(buf,  8, '-');
474 
475             return new String(buf, UTF16);
476         }
477     }
478 
479     /**
480      * Returns a {@code String} object representing the specified
481      * {@code long}.  The argument is converted to signed decimal
482      * representation and returned as a string, exactly as if the
483      * argument and the radix 10 were given as arguments to the {@link
484      * #toString(long, int)} method.
485      *
486      * @param   i   a {@code long} to be converted.
487      * @return  a string representation of the argument in base&nbsp;10.
488      */
toString(long i)489     public static String toString(long i) {
490         int size = stringSize(i);
491         if (COMPACT_STRINGS) {
492             byte[] buf = new byte[size];
493             getChars(i, size, buf);
494             return new String(buf, LATIN1);
495         } else {
496             byte[] buf = new byte[size * 2];
497             StringUTF16.getChars(i, size, buf);
498             return new String(buf, UTF16);
499         }
500     }
501 
502     /**
503      * Returns a string representation of the argument as an unsigned
504      * decimal value.
505      *
506      * The argument is converted to unsigned decimal representation
507      * and returned as a string exactly as if the argument and radix
508      * 10 were given as arguments to the {@link #toUnsignedString(long,
509      * int)} method.
510      *
511      * @param   i  an integer to be converted to an unsigned string.
512      * @return  an unsigned string representation of the argument.
513      * @see     #toUnsignedString(long, int)
514      * @since 1.8
515      */
toUnsignedString(long i)516     public static String toUnsignedString(long i) {
517         return toUnsignedString(i, 10);
518     }
519 
520     /**
521      * Places characters representing the long i into the
522      * character array buf. The characters are placed into
523      * the buffer backwards starting with the least significant
524      * digit at the specified index (exclusive), and working
525      * backwards from there.
526      *
527      * @implNote This method converts positive inputs into negative
528      * values, to cover the Long.MIN_VALUE case. Converting otherwise
529      * (negative to positive) will expose -Long.MIN_VALUE that overflows
530      * long.
531      *
532      * @param i     value to convert
533      * @param index next index, after the least significant digit
534      * @param buf   target buffer, Latin1-encoded
535      * @return index of the most significant digit or minus sign, if present
536      */
getChars(long i, int index, byte[] buf)537     static int getChars(long i, int index, byte[] buf) {
538         long q;
539         int r;
540         int charPos = index;
541 
542         boolean negative = (i < 0);
543         if (!negative) {
544             i = -i;
545         }
546 
547         // Get 2 digits/iteration using longs until quotient fits into an int
548         while (i <= Integer.MIN_VALUE) {
549             q = i / 100;
550             r = (int)((q * 100) - i);
551             i = q;
552             buf[--charPos] = Integer.DigitOnes[r];
553             buf[--charPos] = Integer.DigitTens[r];
554         }
555 
556         // Get 2 digits/iteration using ints
557         int q2;
558         int i2 = (int)i;
559         while (i2 <= -100) {
560             q2 = i2 / 100;
561             r  = (q2 * 100) - i2;
562             i2 = q2;
563             buf[--charPos] = Integer.DigitOnes[r];
564             buf[--charPos] = Integer.DigitTens[r];
565         }
566 
567         // We know there are at most two digits left at this point.
568         q2 = i2 / 10;
569         r  = (q2 * 10) - i2;
570         buf[--charPos] = (byte)('0' + r);
571 
572         // Whatever left is the remaining digit.
573         if (q2 < 0) {
574             buf[--charPos] = (byte)('0' - q2);
575         }
576 
577         if (negative) {
578             buf[--charPos] = (byte)'-';
579         }
580         return charPos;
581     }
582 
583     /**
584      * Returns the string representation size for a given long value.
585      *
586      * @param x long value
587      * @return string size
588      *
589      * @implNote There are other ways to compute this: e.g. binary search,
590      * but values are biased heavily towards zero, and therefore linear search
591      * wins. The iteration results are also routinely inlined in the generated
592      * code after loop unrolling.
593      */
stringSize(long x)594     static int stringSize(long x) {
595         int d = 1;
596         if (x >= 0) {
597             d = 0;
598             x = -x;
599         }
600         long p = -10;
601         for (int i = 1; i < 19; i++) {
602             if (x > p)
603                 return i + d;
604             p = 10 * p;
605         }
606         return 19 + d;
607     }
608 
609     /**
610      * Parses the string argument as a signed {@code long} in the
611      * radix specified by the second argument. The characters in the
612      * string must all be digits of the specified radix (as determined
613      * by whether {@link java.lang.Character#digit(char, int)} returns
614      * a nonnegative value), except that the first character may be an
615      * ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to
616      * indicate a negative value or an ASCII plus sign {@code '+'}
617      * ({@code '\u005Cu002B'}) to indicate a positive value. The
618      * resulting {@code long} value is returned.
619      *
620      * <p>Note that neither the character {@code L}
621      * ({@code '\u005Cu004C'}) nor {@code l}
622      * ({@code '\u005Cu006C'}) is permitted to appear at the end
623      * of the string as a type indicator, as would be permitted in
624      * Java programming language source code - except that either
625      * {@code L} or {@code l} may appear as a digit for a
626      * radix greater than or equal to 22.
627      *
628      * <p>An exception of type {@code NumberFormatException} is
629      * thrown if any of the following situations occurs:
630      * <ul>
631      *
632      * <li>The first argument is {@code null} or is a string of
633      * length zero.
634      *
635      * <li>The {@code radix} is either smaller than {@link
636      * java.lang.Character#MIN_RADIX} or larger than {@link
637      * java.lang.Character#MAX_RADIX}.
638      *
639      * <li>Any character of the string is not a digit of the specified
640      * radix, except that the first character may be a minus sign
641      * {@code '-'} ({@code '\u005Cu002d'}) or plus sign {@code
642      * '+'} ({@code '\u005Cu002B'}) provided that the string is
643      * longer than length 1.
644      *
645      * <li>The value represented by the string is not a value of type
646      *      {@code long}.
647      * </ul>
648      *
649      * <p>Examples:
650      * <blockquote><pre>
651      * parseLong("0", 10) returns 0L
652      * parseLong("473", 10) returns 473L
653      * parseLong("+42", 10) returns 42L
654      * parseLong("-0", 10) returns 0L
655      * parseLong("-FF", 16) returns -255L
656      * parseLong("1100110", 2) returns 102L
657      * parseLong("99", 8) throws a NumberFormatException
658      * parseLong("Hazelnut", 10) throws a NumberFormatException
659      * parseLong("Hazelnut", 36) returns 1356099454469L
660      * </pre></blockquote>
661      *
662      * @param      s       the {@code String} containing the
663      *                     {@code long} representation to be parsed.
664      * @param      radix   the radix to be used while parsing {@code s}.
665      * @return     the {@code long} represented by the string argument in
666      *             the specified radix.
667      * @throws     NumberFormatException  if the string does not contain a
668      *             parsable {@code long}.
669      */
parseLong(String s, int radix)670     public static long parseLong(String s, int radix)
671               throws NumberFormatException
672     {
673         if (s == null) {
674             throw new NumberFormatException("Cannot parse null string");
675         }
676 
677         if (radix < Character.MIN_RADIX) {
678             throw new NumberFormatException("radix " + radix +
679                                             " less than Character.MIN_RADIX");
680         }
681         if (radix > Character.MAX_RADIX) {
682             throw new NumberFormatException("radix " + radix +
683                                             " greater than Character.MAX_RADIX");
684         }
685 
686         boolean negative = false;
687         int i = 0, len = s.length();
688         long limit = -Long.MAX_VALUE;
689 
690         if (len > 0) {
691             char firstChar = s.charAt(0);
692             if (firstChar < '0') { // Possible leading "+" or "-"
693                 if (firstChar == '-') {
694                     negative = true;
695                     limit = Long.MIN_VALUE;
696                 } else if (firstChar != '+') {
697                     throw NumberFormatException.forInputString(s, radix);
698                 }
699 
700                 if (len == 1) { // Cannot have lone "+" or "-"
701                     throw NumberFormatException.forInputString(s, radix);
702                 }
703                 i++;
704             }
705             long multmin = limit / radix;
706             long result = 0;
707             while (i < len) {
708                 // Accumulating negatively avoids surprises near MAX_VALUE
709                 int digit = Character.digit(s.charAt(i++),radix);
710                 if (digit < 0 || result < multmin) {
711                     throw NumberFormatException.forInputString(s, radix);
712                 }
713                 result *= radix;
714                 if (result < limit + digit) {
715                     throw NumberFormatException.forInputString(s, radix);
716                 }
717                 result -= digit;
718             }
719             return negative ? result : -result;
720         } else {
721             throw NumberFormatException.forInputString(s, radix);
722         }
723     }
724 
725     /**
726      * Parses the {@link CharSequence} argument as a signed {@code long} in
727      * the specified {@code radix}, beginning at the specified
728      * {@code beginIndex} and extending to {@code endIndex - 1}.
729      *
730      * <p>The method does not take steps to guard against the
731      * {@code CharSequence} being mutated while parsing.
732      *
733      * @param      s   the {@code CharSequence} containing the {@code long}
734      *                  representation to be parsed
735      * @param      beginIndex   the beginning index, inclusive.
736      * @param      endIndex     the ending index, exclusive.
737      * @param      radix   the radix to be used while parsing {@code s}.
738      * @return     the signed {@code long} represented by the subsequence in
739      *             the specified radix.
740      * @throws     NullPointerException  if {@code s} is null.
741      * @throws     IndexOutOfBoundsException  if {@code beginIndex} is
742      *             negative, or if {@code beginIndex} is greater than
743      *             {@code endIndex} or if {@code endIndex} is greater than
744      *             {@code s.length()}.
745      * @throws     NumberFormatException  if the {@code CharSequence} does not
746      *             contain a parsable {@code long} in the specified
747      *             {@code radix}, or if {@code radix} is either smaller than
748      *             {@link java.lang.Character#MIN_RADIX} or larger than
749      *             {@link java.lang.Character#MAX_RADIX}.
750      * @since  9
751      */
parseLong(CharSequence s, int beginIndex, int endIndex, int radix)752     public static long parseLong(CharSequence s, int beginIndex, int endIndex, int radix)
753                 throws NumberFormatException {
754         Objects.requireNonNull(s);
755 
756         if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) {
757             throw new IndexOutOfBoundsException();
758         }
759         if (radix < Character.MIN_RADIX) {
760             throw new NumberFormatException("radix " + radix +
761                     " less than Character.MIN_RADIX");
762         }
763         if (radix > Character.MAX_RADIX) {
764             throw new NumberFormatException("radix " + radix +
765                     " greater than Character.MAX_RADIX");
766         }
767 
768         boolean negative = false;
769         int i = beginIndex;
770         long limit = -Long.MAX_VALUE;
771 
772         if (i < endIndex) {
773             char firstChar = s.charAt(i);
774             if (firstChar < '0') { // Possible leading "+" or "-"
775                 if (firstChar == '-') {
776                     negative = true;
777                     limit = Long.MIN_VALUE;
778                 } else if (firstChar != '+') {
779                     throw NumberFormatException.forCharSequence(s, beginIndex,
780                             endIndex, i);
781                 }
782                 i++;
783             }
784             if (i >= endIndex) { // Cannot have lone "+", "-" or ""
785                 throw NumberFormatException.forCharSequence(s, beginIndex,
786                         endIndex, i);
787             }
788             long multmin = limit / radix;
789             long result = 0;
790             while (i < endIndex) {
791                 // Accumulating negatively avoids surprises near MAX_VALUE
792                 int digit = Character.digit(s.charAt(i), radix);
793                 if (digit < 0 || result < multmin) {
794                     throw NumberFormatException.forCharSequence(s, beginIndex,
795                             endIndex, i);
796                 }
797                 result *= radix;
798                 if (result < limit + digit) {
799                     throw NumberFormatException.forCharSequence(s, beginIndex,
800                             endIndex, i);
801                 }
802                 i++;
803                 result -= digit;
804             }
805             return negative ? result : -result;
806         } else {
807             throw new NumberFormatException("");
808         }
809     }
810 
811     /**
812      * Parses the string argument as a signed decimal {@code long}.
813      * The characters in the string must all be decimal digits, except
814      * that the first character may be an ASCII minus sign {@code '-'}
815      * ({@code \u005Cu002D'}) to indicate a negative value or an
816      * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to
817      * indicate a positive value. The resulting {@code long} value is
818      * returned, exactly as if the argument and the radix {@code 10}
819      * were given as arguments to the {@link
820      * #parseLong(java.lang.String, int)} method.
821      *
822      * <p>Note that neither the character {@code L}
823      * ({@code '\u005Cu004C'}) nor {@code l}
824      * ({@code '\u005Cu006C'}) is permitted to appear at the end
825      * of the string as a type indicator, as would be permitted in
826      * Java programming language source code.
827      *
828      * @param      s   a {@code String} containing the {@code long}
829      *             representation to be parsed
830      * @return     the {@code long} represented by the argument in
831      *             decimal.
832      * @throws     NumberFormatException  if the string does not contain a
833      *             parsable {@code long}.
834      */
parseLong(String s)835     public static long parseLong(String s) throws NumberFormatException {
836         return parseLong(s, 10);
837     }
838 
839     /**
840      * Parses the string argument as an unsigned {@code long} in the
841      * radix specified by the second argument.  An unsigned integer
842      * maps the values usually associated with negative numbers to
843      * positive numbers larger than {@code MAX_VALUE}.
844      *
845      * The characters in the string must all be digits of the
846      * specified radix (as determined by whether {@link
847      * java.lang.Character#digit(char, int)} returns a nonnegative
848      * value), except that the first character may be an ASCII plus
849      * sign {@code '+'} ({@code '\u005Cu002B'}). The resulting
850      * integer value is returned.
851      *
852      * <p>An exception of type {@code NumberFormatException} is
853      * thrown if any of the following situations occurs:
854      * <ul>
855      * <li>The first argument is {@code null} or is a string of
856      * length zero.
857      *
858      * <li>The radix is either smaller than
859      * {@link java.lang.Character#MIN_RADIX} or
860      * larger than {@link java.lang.Character#MAX_RADIX}.
861      *
862      * <li>Any character of the string is not a digit of the specified
863      * radix, except that the first character may be a plus sign
864      * {@code '+'} ({@code '\u005Cu002B'}) provided that the
865      * string is longer than length 1.
866      *
867      * <li>The value represented by the string is larger than the
868      * largest unsigned {@code long}, 2<sup>64</sup>-1.
869      *
870      * </ul>
871      *
872      *
873      * @param      s   the {@code String} containing the unsigned integer
874      *                  representation to be parsed
875      * @param      radix   the radix to be used while parsing {@code s}.
876      * @return     the unsigned {@code long} represented by the string
877      *             argument in the specified radix.
878      * @throws     NumberFormatException if the {@code String}
879      *             does not contain a parsable {@code long}.
880      * @since 1.8
881      */
parseUnsignedLong(String s, int radix)882     public static long parseUnsignedLong(String s, int radix)
883                 throws NumberFormatException {
884         if (s == null)  {
885             throw new NumberFormatException("Cannot parse null string");
886         }
887 
888         int len = s.length();
889         if (len > 0) {
890             char firstChar = s.charAt(0);
891             if (firstChar == '-') {
892                 throw new
893                     NumberFormatException(String.format("Illegal leading minus sign " +
894                                                        "on unsigned string %s.", s));
895             } else {
896                 if (len <= 12 || // Long.MAX_VALUE in Character.MAX_RADIX is 13 digits
897                     (radix == 10 && len <= 18) ) { // Long.MAX_VALUE in base 10 is 19 digits
898                     return parseLong(s, radix);
899                 }
900 
901                 // No need for range checks on len due to testing above.
902                 long first = parseLong(s, 0, len - 1, radix);
903                 int second = Character.digit(s.charAt(len - 1), radix);
904                 if (second < 0) {
905                     throw new NumberFormatException("Bad digit at end of " + s);
906                 }
907                 long result = first * radix + second;
908 
909                 /*
910                  * Test leftmost bits of multiprecision extension of first*radix
911                  * for overflow. The number of bits needed is defined by
912                  * GUARD_BIT = ceil(log2(Character.MAX_RADIX)) + 1 = 7. Then
913                  * int guard = radix*(int)(first >>> (64 - GUARD_BIT)) and
914                  * overflow is tested by splitting guard in the ranges
915                  * guard < 92, 92 <= guard < 128, and 128 <= guard, where
916                  * 92 = 128 - Character.MAX_RADIX. Note that guard cannot take
917                  * on a value which does not include a prime factor in the legal
918                  * radix range.
919                  */
920                 int guard = radix * (int) (first >>> 57);
921                 if (guard >= 128 ||
922                     (result >= 0 && guard >= 128 - Character.MAX_RADIX)) {
923                     /*
924                      * For purposes of exposition, the programmatic statements
925                      * below should be taken to be multi-precision, i.e., not
926                      * subject to overflow.
927                      *
928                      * A) Condition guard >= 128:
929                      * If guard >= 128 then first*radix >= 2^7 * 2^57 = 2^64
930                      * hence always overflow.
931                      *
932                      * B) Condition guard < 92:
933                      * Define left7 = first >>> 57.
934                      * Given first = (left7 * 2^57) + (first & (2^57 - 1)) then
935                      * result <= (radix*left7)*2^57 + radix*(2^57 - 1) + second.
936                      * Thus if radix*left7 < 92, radix <= 36, and second < 36,
937                      * then result < 92*2^57 + 36*(2^57 - 1) + 36 = 2^64 hence
938                      * never overflow.
939                      *
940                      * C) Condition 92 <= guard < 128:
941                      * first*radix + second >= radix*left7*2^57 + second
942                      * so that first*radix + second >= 92*2^57 + 0 > 2^63
943                      *
944                      * D) Condition guard < 128:
945                      * radix*first <= (radix*left7) * 2^57 + radix*(2^57 - 1)
946                      * so
947                      * radix*first + second <= (radix*left7) * 2^57 + radix*(2^57 - 1) + 36
948                      * thus
949                      * radix*first + second < 128 * 2^57 + 36*2^57 - radix + 36
950                      * whence
951                      * radix*first + second < 2^64 + 2^6*2^57 = 2^64 + 2^63
952                      *
953                      * E) Conditions C, D, and result >= 0:
954                      * C and D combined imply the mathematical result
955                      * 2^63 < first*radix + second < 2^64 + 2^63. The lower
956                      * bound is therefore negative as a signed long, but the
957                      * upper bound is too small to overflow again after the
958                      * signed long overflows to positive above 2^64 - 1. Hence
959                      * result >= 0 implies overflow given C and D.
960                      */
961                     throw new NumberFormatException(String.format("String value %s exceeds " +
962                                                                   "range of unsigned long.", s));
963                 }
964                 return result;
965             }
966         } else {
967             throw NumberFormatException.forInputString(s, radix);
968         }
969     }
970 
971     /**
972      * Parses the {@link CharSequence} argument as an unsigned {@code long} in
973      * the specified {@code radix}, beginning at the specified
974      * {@code beginIndex} and extending to {@code endIndex - 1}.
975      *
976      * <p>The method does not take steps to guard against the
977      * {@code CharSequence} being mutated while parsing.
978      *
979      * @param      s   the {@code CharSequence} containing the unsigned
980      *                 {@code long} representation to be parsed
981      * @param      beginIndex   the beginning index, inclusive.
982      * @param      endIndex     the ending index, exclusive.
983      * @param      radix   the radix to be used while parsing {@code s}.
984      * @return     the unsigned {@code long} represented by the subsequence in
985      *             the specified radix.
986      * @throws     NullPointerException  if {@code s} is null.
987      * @throws     IndexOutOfBoundsException  if {@code beginIndex} is
988      *             negative, or if {@code beginIndex} is greater than
989      *             {@code endIndex} or if {@code endIndex} is greater than
990      *             {@code s.length()}.
991      * @throws     NumberFormatException  if the {@code CharSequence} does not
992      *             contain a parsable unsigned {@code long} in the specified
993      *             {@code radix}, or if {@code radix} is either smaller than
994      *             {@link java.lang.Character#MIN_RADIX} or larger than
995      *             {@link java.lang.Character#MAX_RADIX}.
996      * @since  9
997      */
parseUnsignedLong(CharSequence s, int beginIndex, int endIndex, int radix)998     public static long parseUnsignedLong(CharSequence s, int beginIndex, int endIndex, int radix)
999                 throws NumberFormatException {
1000         Objects.requireNonNull(s);
1001 
1002         if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) {
1003             throw new IndexOutOfBoundsException();
1004         }
1005         int start = beginIndex, len = endIndex - beginIndex;
1006 
1007         if (len > 0) {
1008             char firstChar = s.charAt(start);
1009             if (firstChar == '-') {
1010                 throw new NumberFormatException(String.format("Illegal leading minus sign " +
1011                         "on unsigned string %s.", s.subSequence(start, start + len)));
1012             } else {
1013                 if (len <= 12 || // Long.MAX_VALUE in Character.MAX_RADIX is 13 digits
1014                     (radix == 10 && len <= 18) ) { // Long.MAX_VALUE in base 10 is 19 digits
1015                     return parseLong(s, start, start + len, radix);
1016                 }
1017 
1018                 // No need for range checks on end due to testing above.
1019                 long first = parseLong(s, start, start + len - 1, radix);
1020                 int second = Character.digit(s.charAt(start + len - 1), radix);
1021                 if (second < 0) {
1022                     throw new NumberFormatException("Bad digit at end of " +
1023                             s.subSequence(start, start + len));
1024                 }
1025                 long result = first * radix + second;
1026 
1027                 /*
1028                  * Test leftmost bits of multiprecision extension of first*radix
1029                  * for overflow. The number of bits needed is defined by
1030                  * GUARD_BIT = ceil(log2(Character.MAX_RADIX)) + 1 = 7. Then
1031                  * int guard = radix*(int)(first >>> (64 - GUARD_BIT)) and
1032                  * overflow is tested by splitting guard in the ranges
1033                  * guard < 92, 92 <= guard < 128, and 128 <= guard, where
1034                  * 92 = 128 - Character.MAX_RADIX. Note that guard cannot take
1035                  * on a value which does not include a prime factor in the legal
1036                  * radix range.
1037                  */
1038                 int guard = radix * (int) (first >>> 57);
1039                 if (guard >= 128 ||
1040                         (result >= 0 && guard >= 128 - Character.MAX_RADIX)) {
1041                     /*
1042                      * For purposes of exposition, the programmatic statements
1043                      * below should be taken to be multi-precision, i.e., not
1044                      * subject to overflow.
1045                      *
1046                      * A) Condition guard >= 128:
1047                      * If guard >= 128 then first*radix >= 2^7 * 2^57 = 2^64
1048                      * hence always overflow.
1049                      *
1050                      * B) Condition guard < 92:
1051                      * Define left7 = first >>> 57.
1052                      * Given first = (left7 * 2^57) + (first & (2^57 - 1)) then
1053                      * result <= (radix*left7)*2^57 + radix*(2^57 - 1) + second.
1054                      * Thus if radix*left7 < 92, radix <= 36, and second < 36,
1055                      * then result < 92*2^57 + 36*(2^57 - 1) + 36 = 2^64 hence
1056                      * never overflow.
1057                      *
1058                      * C) Condition 92 <= guard < 128:
1059                      * first*radix + second >= radix*left7*2^57 + second
1060                      * so that first*radix + second >= 92*2^57 + 0 > 2^63
1061                      *
1062                      * D) Condition guard < 128:
1063                      * radix*first <= (radix*left7) * 2^57 + radix*(2^57 - 1)
1064                      * so
1065                      * radix*first + second <= (radix*left7) * 2^57 + radix*(2^57 - 1) + 36
1066                      * thus
1067                      * radix*first + second < 128 * 2^57 + 36*2^57 - radix + 36
1068                      * whence
1069                      * radix*first + second < 2^64 + 2^6*2^57 = 2^64 + 2^63
1070                      *
1071                      * E) Conditions C, D, and result >= 0:
1072                      * C and D combined imply the mathematical result
1073                      * 2^63 < first*radix + second < 2^64 + 2^63. The lower
1074                      * bound is therefore negative as a signed long, but the
1075                      * upper bound is too small to overflow again after the
1076                      * signed long overflows to positive above 2^64 - 1. Hence
1077                      * result >= 0 implies overflow given C and D.
1078                      */
1079                     throw new NumberFormatException(String.format("String value %s exceeds " +
1080                             "range of unsigned long.", s.subSequence(start, start + len)));
1081                 }
1082                 return result;
1083             }
1084         } else {
1085             throw NumberFormatException.forInputString("", radix);
1086         }
1087     }
1088 
1089     /**
1090      * Parses the string argument as an unsigned decimal {@code long}. The
1091      * characters in the string must all be decimal digits, except
1092      * that the first character may be an ASCII plus sign {@code
1093      * '+'} ({@code '\u005Cu002B'}). The resulting integer value
1094      * is returned, exactly as if the argument and the radix 10 were
1095      * given as arguments to the {@link
1096      * #parseUnsignedLong(java.lang.String, int)} method.
1097      *
1098      * @param s   a {@code String} containing the unsigned {@code long}
1099      *            representation to be parsed
1100      * @return    the unsigned {@code long} value represented by the decimal string argument
1101      * @throws    NumberFormatException  if the string does not contain a
1102      *            parsable unsigned integer.
1103      * @since 1.8
1104      */
parseUnsignedLong(String s)1105     public static long parseUnsignedLong(String s) throws NumberFormatException {
1106         return parseUnsignedLong(s, 10);
1107     }
1108 
1109     /**
1110      * Returns a {@code Long} object holding the value
1111      * extracted from the specified {@code String} when parsed
1112      * with the radix given by the second argument.  The first
1113      * argument is interpreted as representing a signed
1114      * {@code long} in the radix specified by the second
1115      * argument, exactly as if the arguments were given to the {@link
1116      * #parseLong(java.lang.String, int)} method. The result is a
1117      * {@code Long} object that represents the {@code long}
1118      * value specified by the string.
1119      *
1120      * <p>In other words, this method returns a {@code Long} object equal
1121      * to the value of:
1122      *
1123      * <blockquote>
1124      *  {@code new Long(Long.parseLong(s, radix))}
1125      * </blockquote>
1126      *
1127      * @param      s       the string to be parsed
1128      * @param      radix   the radix to be used in interpreting {@code s}
1129      * @return     a {@code Long} object holding the value
1130      *             represented by the string argument in the specified
1131      *             radix.
1132      * @throws     NumberFormatException  If the {@code String} does not
1133      *             contain a parsable {@code long}.
1134      */
valueOf(String s, int radix)1135     public static Long valueOf(String s, int radix) throws NumberFormatException {
1136         return Long.valueOf(parseLong(s, radix));
1137     }
1138 
1139     /**
1140      * Returns a {@code Long} object holding the value
1141      * of the specified {@code String}. The argument is
1142      * interpreted as representing a signed decimal {@code long},
1143      * exactly as if the argument were given to the {@link
1144      * #parseLong(java.lang.String)} method. The result is a
1145      * {@code Long} object that represents the integer value
1146      * specified by the string.
1147      *
1148      * <p>In other words, this method returns a {@code Long} object
1149      * equal to the value of:
1150      *
1151      * <blockquote>
1152      *  {@code new Long(Long.parseLong(s))}
1153      * </blockquote>
1154      *
1155      * @param      s   the string to be parsed.
1156      * @return     a {@code Long} object holding the value
1157      *             represented by the string argument.
1158      * @throws     NumberFormatException  If the string cannot be parsed
1159      *             as a {@code long}.
1160      */
valueOf(String s)1161     public static Long valueOf(String s) throws NumberFormatException
1162     {
1163         return Long.valueOf(parseLong(s, 10));
1164     }
1165 
1166     private static class LongCache {
LongCache()1167         private LongCache() {}
1168 
1169         static final Long[] cache;
1170         static Long[] archivedCache;
1171 
1172         static {
1173             int size = -(-128) + 127 + 1;
1174 
1175             // Load and use the archived cache if it exists
1176             CDS.initializeFromArchive(LongCache.class);
1177             if (archivedCache == null || archivedCache.length != size) {
1178                 Long[] c = new Long[size];
1179                 long value = -128;
1180                 for(int i = 0; i < size; i++) {
1181                     c[i] = new Long(value++);
1182                 }
1183                 archivedCache = c;
1184             }
1185             cache = archivedCache;
1186         }
1187     }
1188 
1189     /**
1190      * Returns a {@code Long} instance representing the specified
1191      * {@code long} value.
1192      * If a new {@code Long} instance is not required, this method
1193      * should generally be used in preference to the constructor
1194      * {@link #Long(long)}, as this method is likely to yield
1195      * significantly better space and time performance by caching
1196      * frequently requested values.
1197      *
1198      * This method will always cache values in the range -128 to 127,
1199      * inclusive, and may cache other values outside of this range.
1200      *
1201      * @param  l a long value.
1202      * @return a {@code Long} instance representing {@code l}.
1203      * @since  1.5
1204      */
1205     @IntrinsicCandidate
valueOf(long l)1206     public static Long valueOf(long l) {
1207         final int offset = 128;
1208         if (l >= -128 && l <= 127) { // will cache
1209             return LongCache.cache[(int)l + offset];
1210         }
1211         return new Long(l);
1212     }
1213 
1214     /**
1215      * Decodes a {@code String} into a {@code Long}.
1216      * Accepts decimal, hexadecimal, and octal numbers given by the
1217      * following grammar:
1218      *
1219      * <blockquote>
1220      * <dl>
1221      * <dt><i>DecodableString:</i>
1222      * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
1223      * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
1224      * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
1225      * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
1226      * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
1227      *
1228      * <dt><i>Sign:</i>
1229      * <dd>{@code -}
1230      * <dd>{@code +}
1231      * </dl>
1232      * </blockquote>
1233      *
1234      * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
1235      * are as defined in section {@jls 3.10.1} of
1236      * <cite>The Java Language Specification</cite>,
1237      * except that underscores are not accepted between digits.
1238      *
1239      * <p>The sequence of characters following an optional
1240      * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
1241      * "{@code #}", or leading zero) is parsed as by the {@code
1242      * Long.parseLong} method with the indicated radix (10, 16, or 8).
1243      * This sequence of characters must represent a positive value or
1244      * a {@link NumberFormatException} will be thrown.  The result is
1245      * negated if first character of the specified {@code String} is
1246      * the minus sign.  No whitespace characters are permitted in the
1247      * {@code String}.
1248      *
1249      * @param     nm the {@code String} to decode.
1250      * @return    a {@code Long} object holding the {@code long}
1251      *            value represented by {@code nm}
1252      * @throws    NumberFormatException  if the {@code String} does not
1253      *            contain a parsable {@code long}.
1254      * @see java.lang.Long#parseLong(String, int)
1255      * @since 1.2
1256      */
decode(String nm)1257     public static Long decode(String nm) throws NumberFormatException {
1258         int radix = 10;
1259         int index = 0;
1260         boolean negative = false;
1261         Long result;
1262 
1263         if (nm.isEmpty())
1264             throw new NumberFormatException("Zero length string");
1265         char firstChar = nm.charAt(0);
1266         // Handle sign, if present
1267         if (firstChar == '-') {
1268             negative = true;
1269             index++;
1270         } else if (firstChar == '+')
1271             index++;
1272 
1273         // Handle radix specifier, if present
1274         if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
1275             index += 2;
1276             radix = 16;
1277         }
1278         else if (nm.startsWith("#", index)) {
1279             index ++;
1280             radix = 16;
1281         }
1282         else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
1283             index ++;
1284             radix = 8;
1285         }
1286 
1287         if (nm.startsWith("-", index) || nm.startsWith("+", index))
1288             throw new NumberFormatException("Sign character in wrong position");
1289 
1290         try {
1291             result = Long.valueOf(nm.substring(index), radix);
1292             result = negative ? Long.valueOf(-result.longValue()) : result;
1293         } catch (NumberFormatException e) {
1294             // If number is Long.MIN_VALUE, we'll end up here. The next line
1295             // handles this case, and causes any genuine format error to be
1296             // rethrown.
1297             String constant = negative ? ("-" + nm.substring(index))
1298                                        : nm.substring(index);
1299             result = Long.valueOf(constant, radix);
1300         }
1301         return result;
1302     }
1303 
1304     /**
1305      * The value of the {@code Long}.
1306      *
1307      * @serial
1308      */
1309     private final long value;
1310 
1311     /**
1312      * Constructs a newly allocated {@code Long} object that
1313      * represents the specified {@code long} argument.
1314      *
1315      * @param   value   the value to be represented by the
1316      *          {@code Long} object.
1317      *
1318      * @deprecated
1319      * It is rarely appropriate to use this constructor. The static factory
1320      * {@link #valueOf(long)} is generally a better choice, as it is
1321      * likely to yield significantly better space and time performance.
1322      */
1323     @Deprecated(since="9", forRemoval = true)
Long(long value)1324     public Long(long value) {
1325         this.value = value;
1326     }
1327 
1328     /**
1329      * Constructs a newly allocated {@code Long} object that
1330      * represents the {@code long} value indicated by the
1331      * {@code String} parameter. The string is converted to a
1332      * {@code long} value in exactly the manner used by the
1333      * {@code parseLong} method for radix 10.
1334      *
1335      * @param      s   the {@code String} to be converted to a
1336      *             {@code Long}.
1337      * @throws     NumberFormatException  if the {@code String} does not
1338      *             contain a parsable {@code long}.
1339      *
1340      * @deprecated
1341      * It is rarely appropriate to use this constructor.
1342      * Use {@link #parseLong(String)} to convert a string to a
1343      * {@code long} primitive, or use {@link #valueOf(String)}
1344      * to convert a string to a {@code Long} object.
1345      */
1346     @Deprecated(since="9", forRemoval = true)
Long(String s)1347     public Long(String s) throws NumberFormatException {
1348         this.value = parseLong(s, 10);
1349     }
1350 
1351     /**
1352      * Returns the value of this {@code Long} as a {@code byte} after
1353      * a narrowing primitive conversion.
1354      * @jls 5.1.3 Narrowing Primitive Conversion
1355      */
byteValue()1356     public byte byteValue() {
1357         return (byte)value;
1358     }
1359 
1360     /**
1361      * Returns the value of this {@code Long} as a {@code short} after
1362      * a narrowing primitive conversion.
1363      * @jls 5.1.3 Narrowing Primitive Conversion
1364      */
shortValue()1365     public short shortValue() {
1366         return (short)value;
1367     }
1368 
1369     /**
1370      * Returns the value of this {@code Long} as an {@code int} after
1371      * a narrowing primitive conversion.
1372      * @jls 5.1.3 Narrowing Primitive Conversion
1373      */
intValue()1374     public int intValue() {
1375         return (int)value;
1376     }
1377 
1378     /**
1379      * Returns the value of this {@code Long} as a
1380      * {@code long} value.
1381      */
1382     @IntrinsicCandidate
longValue()1383     public long longValue() {
1384         return value;
1385     }
1386 
1387     /**
1388      * Returns the value of this {@code Long} as a {@code float} after
1389      * a widening primitive conversion.
1390      * @jls 5.1.2 Widening Primitive Conversion
1391      */
floatValue()1392     public float floatValue() {
1393         return (float)value;
1394     }
1395 
1396     /**
1397      * Returns the value of this {@code Long} as a {@code double}
1398      * after a widening primitive conversion.
1399      * @jls 5.1.2 Widening Primitive Conversion
1400      */
doubleValue()1401     public double doubleValue() {
1402         return (double)value;
1403     }
1404 
1405     /**
1406      * Returns a {@code String} object representing this
1407      * {@code Long}'s value.  The value is converted to signed
1408      * decimal representation and returned as a string, exactly as if
1409      * the {@code long} value were given as an argument to the
1410      * {@link java.lang.Long#toString(long)} method.
1411      *
1412      * @return  a string representation of the value of this object in
1413      *          base&nbsp;10.
1414      */
toString()1415     public String toString() {
1416         return toString(value);
1417     }
1418 
1419     /**
1420      * Returns a hash code for this {@code Long}. The result is
1421      * the exclusive OR of the two halves of the primitive
1422      * {@code long} value held by this {@code Long}
1423      * object. That is, the hashcode is the value of the expression:
1424      *
1425      * <blockquote>
1426      *  {@code (int)(this.longValue()^(this.longValue()>>>32))}
1427      * </blockquote>
1428      *
1429      * @return  a hash code value for this object.
1430      */
1431     @Override
hashCode()1432     public int hashCode() {
1433         return Long.hashCode(value);
1434     }
1435 
1436     /**
1437      * Returns a hash code for a {@code long} value; compatible with
1438      * {@code Long.hashCode()}.
1439      *
1440      * @param value the value to hash
1441      * @return a hash code value for a {@code long} value.
1442      * @since 1.8
1443      */
hashCode(long value)1444     public static int hashCode(long value) {
1445         return (int)(value ^ (value >>> 32));
1446     }
1447 
1448     /**
1449      * Compares this object to the specified object.  The result is
1450      * {@code true} if and only if the argument is not
1451      * {@code null} and is a {@code Long} object that
1452      * contains the same {@code long} value as this object.
1453      *
1454      * @param   obj   the object to compare with.
1455      * @return  {@code true} if the objects are the same;
1456      *          {@code false} otherwise.
1457      */
equals(Object obj)1458     public boolean equals(Object obj) {
1459         if (obj instanceof Long) {
1460             return value == ((Long)obj).longValue();
1461         }
1462         return false;
1463     }
1464 
1465     /**
1466      * Determines the {@code long} value of the system property
1467      * with the specified name.
1468      *
1469      * <p>The first argument is treated as the name of a system
1470      * property.  System properties are accessible through the {@link
1471      * java.lang.System#getProperty(java.lang.String)} method. The
1472      * string value of this property is then interpreted as a {@code
1473      * long} value using the grammar supported by {@link Long#decode decode}
1474      * and a {@code Long} object representing this value is returned.
1475      *
1476      * <p>If there is no property with the specified name, if the
1477      * specified name is empty or {@code null}, or if the property
1478      * does not have the correct numeric format, then {@code null} is
1479      * returned.
1480      *
1481      * <p>In other words, this method returns a {@code Long} object
1482      * equal to the value of:
1483      *
1484      * <blockquote>
1485      *  {@code getLong(nm, null)}
1486      * </blockquote>
1487      *
1488      * @param   nm   property name.
1489      * @return  the {@code Long} value of the property.
1490      * @throws  SecurityException for the same reasons as
1491      *          {@link System#getProperty(String) System.getProperty}
1492      * @see     java.lang.System#getProperty(java.lang.String)
1493      * @see     java.lang.System#getProperty(java.lang.String, java.lang.String)
1494      */
getLong(String nm)1495     public static Long getLong(String nm) {
1496         return getLong(nm, null);
1497     }
1498 
1499     /**
1500      * Determines the {@code long} value of the system property
1501      * with the specified name.
1502      *
1503      * <p>The first argument is treated as the name of a system
1504      * property.  System properties are accessible through the {@link
1505      * java.lang.System#getProperty(java.lang.String)} method. The
1506      * string value of this property is then interpreted as a {@code
1507      * long} value using the grammar supported by {@link Long#decode decode}
1508      * and a {@code Long} object representing this value is returned.
1509      *
1510      * <p>The second argument is the default value. A {@code Long} object
1511      * that represents the value of the second argument is returned if there
1512      * is no property of the specified name, if the property does not have
1513      * the correct numeric format, or if the specified name is empty or null.
1514      *
1515      * <p>In other words, this method returns a {@code Long} object equal
1516      * to the value of:
1517      *
1518      * <blockquote>
1519      *  {@code getLong(nm, new Long(val))}
1520      * </blockquote>
1521      *
1522      * but in practice it may be implemented in a manner such as:
1523      *
1524      * <blockquote><pre>
1525      * Long result = getLong(nm, null);
1526      * return (result == null) ? new Long(val) : result;
1527      * </pre></blockquote>
1528      *
1529      * to avoid the unnecessary allocation of a {@code Long} object when
1530      * the default value is not needed.
1531      *
1532      * @param   nm    property name.
1533      * @param   val   default value.
1534      * @return  the {@code Long} value of the property.
1535      * @throws  SecurityException for the same reasons as
1536      *          {@link System#getProperty(String) System.getProperty}
1537      * @see     java.lang.System#getProperty(java.lang.String)
1538      * @see     java.lang.System#getProperty(java.lang.String, java.lang.String)
1539      */
getLong(String nm, long val)1540     public static Long getLong(String nm, long val) {
1541         Long result = Long.getLong(nm, null);
1542         return (result == null) ? Long.valueOf(val) : result;
1543     }
1544 
1545     /**
1546      * Returns the {@code long} value of the system property with
1547      * the specified name.  The first argument is treated as the name
1548      * of a system property.  System properties are accessible through
1549      * the {@link java.lang.System#getProperty(java.lang.String)}
1550      * method. The string value of this property is then interpreted
1551      * as a {@code long} value, as per the
1552      * {@link Long#decode decode} method, and a {@code Long} object
1553      * representing this value is returned; in summary:
1554      *
1555      * <ul>
1556      * <li>If the property value begins with the two ASCII characters
1557      * {@code 0x} or the ASCII character {@code #}, not followed by
1558      * a minus sign, then the rest of it is parsed as a hexadecimal integer
1559      * exactly as for the method {@link #valueOf(java.lang.String, int)}
1560      * with radix 16.
1561      * <li>If the property value begins with the ASCII character
1562      * {@code 0} followed by another character, it is parsed as
1563      * an octal integer exactly as by the method {@link
1564      * #valueOf(java.lang.String, int)} with radix 8.
1565      * <li>Otherwise the property value is parsed as a decimal
1566      * integer exactly as by the method
1567      * {@link #valueOf(java.lang.String, int)} with radix 10.
1568      * </ul>
1569      *
1570      * <p>Note that, in every case, neither {@code L}
1571      * ({@code '\u005Cu004C'}) nor {@code l}
1572      * ({@code '\u005Cu006C'}) is permitted to appear at the end
1573      * of the property value as a type indicator, as would be
1574      * permitted in Java programming language source code.
1575      *
1576      * <p>The second argument is the default value. The default value is
1577      * returned if there is no property of the specified name, if the
1578      * property does not have the correct numeric format, or if the
1579      * specified name is empty or {@code null}.
1580      *
1581      * @param   nm   property name.
1582      * @param   val   default value.
1583      * @return  the {@code Long} value of the property.
1584      * @throws  SecurityException for the same reasons as
1585      *          {@link System#getProperty(String) System.getProperty}
1586      * @see     System#getProperty(java.lang.String)
1587      * @see     System#getProperty(java.lang.String, java.lang.String)
1588      */
getLong(String nm, Long val)1589     public static Long getLong(String nm, Long val) {
1590         String v = null;
1591         try {
1592             v = System.getProperty(nm);
1593         } catch (IllegalArgumentException | NullPointerException e) {
1594         }
1595         if (v != null) {
1596             try {
1597                 return Long.decode(v);
1598             } catch (NumberFormatException e) {
1599             }
1600         }
1601         return val;
1602     }
1603 
1604     /**
1605      * Compares two {@code Long} objects numerically.
1606      *
1607      * @param   anotherLong   the {@code Long} to be compared.
1608      * @return  the value {@code 0} if this {@code Long} is
1609      *          equal to the argument {@code Long}; a value less than
1610      *          {@code 0} if this {@code Long} is numerically less
1611      *          than the argument {@code Long}; and a value greater
1612      *          than {@code 0} if this {@code Long} is numerically
1613      *           greater than the argument {@code Long} (signed
1614      *           comparison).
1615      * @since   1.2
1616      */
compareTo(Long anotherLong)1617     public int compareTo(Long anotherLong) {
1618         return compare(this.value, anotherLong.value);
1619     }
1620 
1621     /**
1622      * Compares two {@code long} values numerically.
1623      * The value returned is identical to what would be returned by:
1624      * <pre>
1625      *    Long.valueOf(x).compareTo(Long.valueOf(y))
1626      * </pre>
1627      *
1628      * @param  x the first {@code long} to compare
1629      * @param  y the second {@code long} to compare
1630      * @return the value {@code 0} if {@code x == y};
1631      *         a value less than {@code 0} if {@code x < y}; and
1632      *         a value greater than {@code 0} if {@code x > y}
1633      * @since 1.7
1634      */
compare(long x, long y)1635     public static int compare(long x, long y) {
1636         return (x < y) ? -1 : ((x == y) ? 0 : 1);
1637     }
1638 
1639     /**
1640      * Compares two {@code long} values numerically treating the values
1641      * as unsigned.
1642      *
1643      * @param  x the first {@code long} to compare
1644      * @param  y the second {@code long} to compare
1645      * @return the value {@code 0} if {@code x == y}; a value less
1646      *         than {@code 0} if {@code x < y} as unsigned values; and
1647      *         a value greater than {@code 0} if {@code x > y} as
1648      *         unsigned values
1649      * @since 1.8
1650      */
compareUnsigned(long x, long y)1651     public static int compareUnsigned(long x, long y) {
1652         return compare(x + MIN_VALUE, y + MIN_VALUE);
1653     }
1654 
1655 
1656     /**
1657      * Returns the unsigned quotient of dividing the first argument by
1658      * the second where each argument and the result is interpreted as
1659      * an unsigned value.
1660      *
1661      * <p>Note that in two's complement arithmetic, the three other
1662      * basic arithmetic operations of add, subtract, and multiply are
1663      * bit-wise identical if the two operands are regarded as both
1664      * being signed or both being unsigned.  Therefore separate {@code
1665      * addUnsigned}, etc. methods are not provided.
1666      *
1667      * @param dividend the value to be divided
1668      * @param divisor the value doing the dividing
1669      * @return the unsigned quotient of the first argument divided by
1670      * the second argument
1671      * @see #remainderUnsigned
1672      * @since 1.8
1673      */
divideUnsigned(long dividend, long divisor)1674     public static long divideUnsigned(long dividend, long divisor) {
1675         /* See Hacker's Delight (2nd ed), section 9.3 */
1676         if (divisor >= 0) {
1677             final long q = (dividend >>> 1) / divisor << 1;
1678             final long r = dividend - q * divisor;
1679             return q + ((r | ~(r - divisor)) >>> (Long.SIZE - 1));
1680         }
1681         return (dividend & ~(dividend - divisor)) >>> (Long.SIZE - 1);
1682     }
1683 
1684     /**
1685      * Returns the unsigned remainder from dividing the first argument
1686      * by the second where each argument and the result is interpreted
1687      * as an unsigned value.
1688      *
1689      * @param dividend the value to be divided
1690      * @param divisor the value doing the dividing
1691      * @return the unsigned remainder of the first argument divided by
1692      * the second argument
1693      * @see #divideUnsigned
1694      * @since 1.8
1695      */
remainderUnsigned(long dividend, long divisor)1696     public static long remainderUnsigned(long dividend, long divisor) {
1697         /* See Hacker's Delight (2nd ed), section 9.3 */
1698         if (divisor >= 0) {
1699             final long q = (dividend >>> 1) / divisor << 1;
1700             final long r = dividend - q * divisor;
1701             /*
1702              * Here, 0 <= r < 2 * divisor
1703              * (1) When 0 <= r < divisor, the remainder is simply r.
1704              * (2) Otherwise the remainder is r - divisor.
1705              *
1706              * In case (1), r - divisor < 0. Applying ~ produces a long with
1707              * sign bit 0, so >> produces 0. The returned value is thus r.
1708              *
1709              * In case (2), a similar reasoning shows that >> produces -1,
1710              * so the returned value is r - divisor.
1711              */
1712             return r - ((~(r - divisor) >> (Long.SIZE - 1)) & divisor);
1713         }
1714         /*
1715          * (1) When dividend >= 0, the remainder is dividend.
1716          * (2) Otherwise
1717          *      (2.1) When dividend < divisor, the remainder is dividend.
1718          *      (2.2) Otherwise the remainder is dividend - divisor
1719          *
1720          * A reasoning similar to the above shows that the returned value
1721          * is as expected.
1722          */
1723         return dividend - (((dividend & ~(dividend - divisor)) >> (Long.SIZE - 1)) & divisor);
1724     }
1725 
1726     // Bit Twiddling
1727 
1728     /**
1729      * The number of bits used to represent a {@code long} value in two's
1730      * complement binary form.
1731      *
1732      * @since 1.5
1733      */
1734     @Native public static final int SIZE = 64;
1735 
1736     /**
1737      * The number of bytes used to represent a {@code long} value in two's
1738      * complement binary form.
1739      *
1740      * @since 1.8
1741      */
1742     public static final int BYTES = SIZE / Byte.SIZE;
1743 
1744     /**
1745      * Returns a {@code long} value with at most a single one-bit, in the
1746      * position of the highest-order ("leftmost") one-bit in the specified
1747      * {@code long} value.  Returns zero if the specified value has no
1748      * one-bits in its two's complement binary representation, that is, if it
1749      * is equal to zero.
1750      *
1751      * @param i the value whose highest one bit is to be computed
1752      * @return a {@code long} value with a single one-bit, in the position
1753      *     of the highest-order one-bit in the specified value, or zero if
1754      *     the specified value is itself equal to zero.
1755      * @since 1.5
1756      */
highestOneBit(long i)1757     public static long highestOneBit(long i) {
1758         return i & (MIN_VALUE >>> numberOfLeadingZeros(i));
1759     }
1760 
1761     /**
1762      * Returns a {@code long} value with at most a single one-bit, in the
1763      * position of the lowest-order ("rightmost") one-bit in the specified
1764      * {@code long} value.  Returns zero if the specified value has no
1765      * one-bits in its two's complement binary representation, that is, if it
1766      * is equal to zero.
1767      *
1768      * @param i the value whose lowest one bit is to be computed
1769      * @return a {@code long} value with a single one-bit, in the position
1770      *     of the lowest-order one-bit in the specified value, or zero if
1771      *     the specified value is itself equal to zero.
1772      * @since 1.5
1773      */
lowestOneBit(long i)1774     public static long lowestOneBit(long i) {
1775         // HD, Section 2-1
1776         return i & -i;
1777     }
1778 
1779     /**
1780      * Returns the number of zero bits preceding the highest-order
1781      * ("leftmost") one-bit in the two's complement binary representation
1782      * of the specified {@code long} value.  Returns 64 if the
1783      * specified value has no one-bits in its two's complement representation,
1784      * in other words if it is equal to zero.
1785      *
1786      * <p>Note that this method is closely related to the logarithm base 2.
1787      * For all positive {@code long} values x:
1788      * <ul>
1789      * <li>floor(log<sub>2</sub>(x)) = {@code 63 - numberOfLeadingZeros(x)}
1790      * <li>ceil(log<sub>2</sub>(x)) = {@code 64 - numberOfLeadingZeros(x - 1)}
1791      * </ul>
1792      *
1793      * @param i the value whose number of leading zeros is to be computed
1794      * @return the number of zero bits preceding the highest-order
1795      *     ("leftmost") one-bit in the two's complement binary representation
1796      *     of the specified {@code long} value, or 64 if the value
1797      *     is equal to zero.
1798      * @since 1.5
1799      */
1800     @IntrinsicCandidate
numberOfLeadingZeros(long i)1801     public static int numberOfLeadingZeros(long i) {
1802         int x = (int)(i >>> 32);
1803         return x == 0 ? 32 + Integer.numberOfLeadingZeros((int)i)
1804                 : Integer.numberOfLeadingZeros(x);
1805     }
1806 
1807     /**
1808      * Returns the number of zero bits following the lowest-order ("rightmost")
1809      * one-bit in the two's complement binary representation of the specified
1810      * {@code long} value.  Returns 64 if the specified value has no
1811      * one-bits in its two's complement representation, in other words if it is
1812      * equal to zero.
1813      *
1814      * @param i the value whose number of trailing zeros is to be computed
1815      * @return the number of zero bits following the lowest-order ("rightmost")
1816      *     one-bit in the two's complement binary representation of the
1817      *     specified {@code long} value, or 64 if the value is equal
1818      *     to zero.
1819      * @since 1.5
1820      */
1821     @IntrinsicCandidate
numberOfTrailingZeros(long i)1822     public static int numberOfTrailingZeros(long i) {
1823         int x = (int)i;
1824         return x == 0 ? 32 + Integer.numberOfTrailingZeros((int)(i >>> 32))
1825                 : Integer.numberOfTrailingZeros(x);
1826     }
1827 
1828     /**
1829      * Returns the number of one-bits in the two's complement binary
1830      * representation of the specified {@code long} value.  This function is
1831      * sometimes referred to as the <i>population count</i>.
1832      *
1833      * @param i the value whose bits are to be counted
1834      * @return the number of one-bits in the two's complement binary
1835      *     representation of the specified {@code long} value.
1836      * @since 1.5
1837      */
1838      @IntrinsicCandidate
bitCount(long i)1839      public static int bitCount(long i) {
1840         // HD, Figure 5-2
1841         i = i - ((i >>> 1) & 0x5555555555555555L);
1842         i = (i & 0x3333333333333333L) + ((i >>> 2) & 0x3333333333333333L);
1843         i = (i + (i >>> 4)) & 0x0f0f0f0f0f0f0f0fL;
1844         i = i + (i >>> 8);
1845         i = i + (i >>> 16);
1846         i = i + (i >>> 32);
1847         return (int)i & 0x7f;
1848      }
1849 
1850     /**
1851      * Returns the value obtained by rotating the two's complement binary
1852      * representation of the specified {@code long} value left by the
1853      * specified number of bits.  (Bits shifted out of the left hand, or
1854      * high-order, side reenter on the right, or low-order.)
1855      *
1856      * <p>Note that left rotation with a negative distance is equivalent to
1857      * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1858      * distance)}.  Note also that rotation by any multiple of 64 is a
1859      * no-op, so all but the last six bits of the rotation distance can be
1860      * ignored, even if the distance is negative: {@code rotateLeft(val,
1861      * distance) == rotateLeft(val, distance & 0x3F)}.
1862      *
1863      * @param i the value whose bits are to be rotated left
1864      * @param distance the number of bit positions to rotate left
1865      * @return the value obtained by rotating the two's complement binary
1866      *     representation of the specified {@code long} value left by the
1867      *     specified number of bits.
1868      * @since 1.5
1869      */
rotateLeft(long i, int distance)1870     public static long rotateLeft(long i, int distance) {
1871         return (i << distance) | (i >>> -distance);
1872     }
1873 
1874     /**
1875      * Returns the value obtained by rotating the two's complement binary
1876      * representation of the specified {@code long} value right by the
1877      * specified number of bits.  (Bits shifted out of the right hand, or
1878      * low-order, side reenter on the left, or high-order.)
1879      *
1880      * <p>Note that right rotation with a negative distance is equivalent to
1881      * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1882      * distance)}.  Note also that rotation by any multiple of 64 is a
1883      * no-op, so all but the last six bits of the rotation distance can be
1884      * ignored, even if the distance is negative: {@code rotateRight(val,
1885      * distance) == rotateRight(val, distance & 0x3F)}.
1886      *
1887      * @param i the value whose bits are to be rotated right
1888      * @param distance the number of bit positions to rotate right
1889      * @return the value obtained by rotating the two's complement binary
1890      *     representation of the specified {@code long} value right by the
1891      *     specified number of bits.
1892      * @since 1.5
1893      */
rotateRight(long i, int distance)1894     public static long rotateRight(long i, int distance) {
1895         return (i >>> distance) | (i << -distance);
1896     }
1897 
1898     /**
1899      * Returns the value obtained by reversing the order of the bits in the
1900      * two's complement binary representation of the specified {@code long}
1901      * value.
1902      *
1903      * @param i the value to be reversed
1904      * @return the value obtained by reversing order of the bits in the
1905      *     specified {@code long} value.
1906      * @since 1.5
1907      */
reverse(long i)1908     public static long reverse(long i) {
1909         // HD, Figure 7-1
1910         i = (i & 0x5555555555555555L) << 1 | (i >>> 1) & 0x5555555555555555L;
1911         i = (i & 0x3333333333333333L) << 2 | (i >>> 2) & 0x3333333333333333L;
1912         i = (i & 0x0f0f0f0f0f0f0f0fL) << 4 | (i >>> 4) & 0x0f0f0f0f0f0f0f0fL;
1913 
1914         return reverseBytes(i);
1915     }
1916 
1917     /**
1918      * Returns the signum function of the specified {@code long} value.  (The
1919      * return value is -1 if the specified value is negative; 0 if the
1920      * specified value is zero; and 1 if the specified value is positive.)
1921      *
1922      * @param i the value whose signum is to be computed
1923      * @return the signum function of the specified {@code long} value.
1924      * @since 1.5
1925      */
signum(long i)1926     public static int signum(long i) {
1927         // HD, Section 2-7
1928         return (int) ((i >> 63) | (-i >>> 63));
1929     }
1930 
1931     /**
1932      * Returns the value obtained by reversing the order of the bytes in the
1933      * two's complement representation of the specified {@code long} value.
1934      *
1935      * @param i the value whose bytes are to be reversed
1936      * @return the value obtained by reversing the bytes in the specified
1937      *     {@code long} value.
1938      * @since 1.5
1939      */
1940     @IntrinsicCandidate
reverseBytes(long i)1941     public static long reverseBytes(long i) {
1942         i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
1943         return (i << 48) | ((i & 0xffff0000L) << 16) |
1944             ((i >>> 16) & 0xffff0000L) | (i >>> 48);
1945     }
1946 
1947     /**
1948      * Adds two {@code long} values together as per the + operator.
1949      *
1950      * @param a the first operand
1951      * @param b the second operand
1952      * @return the sum of {@code a} and {@code b}
1953      * @see java.util.function.BinaryOperator
1954      * @since 1.8
1955      */
sum(long a, long b)1956     public static long sum(long a, long b) {
1957         return a + b;
1958     }
1959 
1960     /**
1961      * Returns the greater of two {@code long} values
1962      * as if by calling {@link Math#max(long, long) Math.max}.
1963      *
1964      * @param a the first operand
1965      * @param b the second operand
1966      * @return the greater of {@code a} and {@code b}
1967      * @see java.util.function.BinaryOperator
1968      * @since 1.8
1969      */
max(long a, long b)1970     public static long max(long a, long b) {
1971         return Math.max(a, b);
1972     }
1973 
1974     /**
1975      * Returns the smaller of two {@code long} values
1976      * as if by calling {@link Math#min(long, long) Math.min}.
1977      *
1978      * @param a the first operand
1979      * @param b the second operand
1980      * @return the smaller of {@code a} and {@code b}
1981      * @see java.util.function.BinaryOperator
1982      * @since 1.8
1983      */
min(long a, long b)1984     public static long min(long a, long b) {
1985         return Math.min(a, b);
1986     }
1987 
1988     /**
1989      * Returns an {@link Optional} containing the nominal descriptor for this
1990      * instance, which is the instance itself.
1991      *
1992      * @return an {@link Optional} describing the {@linkplain Long} instance
1993      * @since 12
1994      */
1995     @Override
describeConstable()1996     public Optional<Long> describeConstable() {
1997         return Optional.of(this);
1998     }
1999 
2000     /**
2001      * Resolves this instance as a {@link ConstantDesc}, the result of which is
2002      * the instance itself.
2003      *
2004      * @param lookup ignored
2005      * @return the {@linkplain Long} instance
2006      * @since 12
2007      */
2008     @Override
resolveConstantDesc(MethodHandles.Lookup lookup)2009     public Long resolveConstantDesc(MethodHandles.Lookup lookup) {
2010         return this;
2011     }
2012 
2013     /** use serialVersionUID from JDK 1.0.2 for interoperability */
2014     @java.io.Serial
2015     @Native private static final long serialVersionUID = 4290774380558885855L;
2016 }
2017