001    /* Long.java -- object wrapper for long
002       Copyright (C) 1998, 1999, 2001, 2002, 2004, 2005 Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    
039    package java.lang;
040    
041    /**
042     * Instances of class <code>Long</code> represent primitive
043     * <code>long</code> values.
044     *
045     * Additionally, this class provides various helper functions and variables
046     * related to longs.
047     *
048     * @author Paul Fisher
049     * @author John Keiser
050     * @author Warren Levy
051     * @author Eric Blake (ebb9@email.byu.edu)
052     * @author Tom Tromey (tromey@redhat.com)
053     * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
054     * @since 1.0
055     * @status updated to 1.5
056     */
057    public final class Long extends Number implements Comparable<Long>
058    {
059      /**
060       * Compatible with JDK 1.0.2+.
061       */
062      private static final long serialVersionUID = 4290774380558885855L;
063    
064      /**
065       * The minimum value a <code>long</code> can represent is
066       * -9223372036854775808L (or -2<sup>63</sup>).
067       */
068      public static final long MIN_VALUE = 0x8000000000000000L;
069    
070      /**
071       * The maximum value a <code>long</code> can represent is
072       * 9223372036854775807 (or 2<sup>63</sup> - 1).
073       */
074      public static final long MAX_VALUE = 0x7fffffffffffffffL;
075    
076      /**
077       * The primitive type <code>long</code> is represented by this
078       * <code>Class</code> object.
079       * @since 1.1
080       */
081      public static final Class<Long> TYPE = (Class<Long>) VMClassLoader.getPrimitiveClass ('J');
082    
083      /**
084       * The number of bits needed to represent a <code>long</code>.
085       * @since 1.5
086       */
087      public static final int SIZE = 64;
088    
089      /**
090       * The immutable value of this Long.
091       *
092       * @serial the wrapped long
093       */
094      private final long value;
095    
096      /**
097       * Create a <code>Long</code> object representing the value of the
098       * <code>long</code> argument.
099       *
100       * @param value the value to use
101       */
102      public Long(long value)
103      {
104        this.value = value;
105      }
106    
107      /**
108       * Create a <code>Long</code> object representing the value of the
109       * argument after conversion to a <code>long</code>.
110       *
111       * @param s the string to convert
112       * @throws NumberFormatException if the String does not contain a long
113       * @see #valueOf(String)
114       */
115      public Long(String s)
116      {
117        value = parseLong(s, 10, false);
118      }
119    
120      /**
121       * Converts the <code>long</code> to a <code>String</code> using
122       * the specified radix (base). If the radix exceeds
123       * <code>Character.MIN_RADIX</code> or <code>Character.MAX_RADIX</code>, 10
124       * is used instead. If the result is negative, the leading character is
125       * '-' ('\\u002D'). The remaining characters come from
126       * <code>Character.forDigit(digit, radix)</code> ('0'-'9','a'-'z').
127       *
128       * @param num the <code>long</code> to convert to <code>String</code>
129       * @param radix the radix (base) to use in the conversion
130       * @return the <code>String</code> representation of the argument
131       */
132      public static String toString(long num, int radix)
133      {
134        // Use the Integer toString for efficiency if possible.
135        if ((int) num == num)
136          return Integer.toString((int) num, radix);
137    
138        if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
139          radix = 10;
140    
141        // For negative numbers, print out the absolute value w/ a leading '-'.
142        // Use an array large enough for a binary number.
143        char[] buffer = new char[65];
144        int i = 65;
145        boolean isNeg = false;
146        if (num < 0)
147          {
148            isNeg = true;
149            num = -num;
150    
151            // When the value is MIN_VALUE, it overflows when made positive
152            if (num < 0)
153              {
154                buffer[--i] = digits[(int) (-(num + radix) % radix)];
155                num = -(num / radix);
156              }
157          }
158    
159        do
160          {
161            buffer[--i] = digits[(int) (num % radix)];
162            num /= radix;
163          }
164        while (num > 0);
165    
166        if (isNeg)
167          buffer[--i] = '-';
168    
169        // Package constructor avoids an array copy.
170        return new String(buffer, i, 65 - i, true);
171      }
172    
173      /**
174       * Converts the <code>long</code> to a <code>String</code> assuming it is
175       * unsigned in base 16.
176       *
177       * @param l the <code>long</code> to convert to <code>String</code>
178       * @return the <code>String</code> representation of the argument
179       */
180      public static String toHexString(long l)
181      {
182        return toUnsignedString(l, 4);
183      }
184    
185      /**
186       * Converts the <code>long</code> to a <code>String</code> assuming it is
187       * unsigned in base 8.
188       *
189       * @param l the <code>long</code> to convert to <code>String</code>
190       * @return the <code>String</code> representation of the argument
191       */
192      public static String toOctalString(long l)
193      {
194        return toUnsignedString(l, 3);
195      }
196    
197      /**
198       * Converts the <code>long</code> to a <code>String</code> assuming it is
199       * unsigned in base 2.
200       *
201       * @param l the <code>long</code> to convert to <code>String</code>
202       * @return the <code>String</code> representation of the argument
203       */
204      public static String toBinaryString(long l)
205      {
206        return toUnsignedString(l, 1);
207      }
208    
209      /**
210       * Converts the <code>long</code> to a <code>String</code> and assumes
211       * a radix of 10.
212       *
213       * @param num the <code>long</code> to convert to <code>String</code>
214       * @return the <code>String</code> representation of the argument
215       * @see #toString(long, int)
216       */
217      public static String toString(long num)
218      {
219        return toString(num, 10);
220      }
221    
222      /**
223       * Converts the specified <code>String</code> into an <code>int</code>
224       * using the specified radix (base). The string must not be <code>null</code>
225       * or empty. It may begin with an optional '-', which will negate the answer,
226       * provided that there are also valid digits. Each digit is parsed as if by
227       * <code>Character.digit(d, radix)</code>, and must be in the range
228       * <code>0</code> to <code>radix - 1</code>. Finally, the result must be
229       * within <code>MIN_VALUE</code> to <code>MAX_VALUE</code>, inclusive.
230       * Unlike Double.parseDouble, you may not have a leading '+'; and 'l' or
231       * 'L' as the last character is only valid in radices 22 or greater, where
232       * it is a digit and not a type indicator.
233       *
234       * @param str the <code>String</code> to convert
235       * @param radix the radix (base) to use in the conversion
236       * @return the <code>String</code> argument converted to <code>long</code>
237       * @throws NumberFormatException if <code>s</code> cannot be parsed as a
238       *         <code>long</code>
239       */
240      public static long parseLong(String str, int radix)
241      {
242        return parseLong(str, radix, false);
243      }
244    
245      /**
246       * Converts the specified <code>String</code> into a <code>long</code>.
247       * This function assumes a radix of 10.
248       *
249       * @param s the <code>String</code> to convert
250       * @return the <code>int</code> value of <code>s</code>
251       * @throws NumberFormatException if <code>s</code> cannot be parsed as a
252       *         <code>long</code>
253       * @see #parseLong(String, int)
254       */
255      public static long parseLong(String s)
256      {
257        return parseLong(s, 10, false);
258      }
259    
260      /**
261       * Creates a new <code>Long</code> object using the <code>String</code>
262       * and specified radix (base).
263       *
264       * @param s the <code>String</code> to convert
265       * @param radix the radix (base) to convert with
266       * @return the new <code>Long</code>
267       * @throws NumberFormatException if <code>s</code> cannot be parsed as a
268       *         <code>long</code>
269       * @see #parseLong(String, int)
270       */
271      public static Long valueOf(String s, int radix)
272      {
273        return new Long(parseLong(s, radix, false));
274      }
275    
276      /**
277       * Creates a new <code>Long</code> object using the <code>String</code>,
278       * assuming a radix of 10.
279       *
280       * @param s the <code>String</code> to convert
281       * @return the new <code>Long</code>
282       * @throws NumberFormatException if <code>s</code> cannot be parsed as a
283       *         <code>long</code>
284       * @see #Long(String)
285       * @see #parseLong(String)
286       */
287      public static Long valueOf(String s)
288      {
289        return new Long(parseLong(s, 10, false));
290      }
291    
292      /**
293       * Returns a <code>Long</code> object wrapping the value.
294       *
295       * @param val the value to wrap
296       * @return the <code>Long</code>
297       * @since 1.5
298       */
299      public static synchronized Long valueOf(long val)
300      {
301        // We aren't required to cache here.  We could, though perhaps we
302        // ought to consider that as an empirical question.
303        return new Long(val);
304      }
305    
306      /**
307       * Convert the specified <code>String</code> into a <code>Long</code>.
308       * The <code>String</code> may represent decimal, hexadecimal, or
309       * octal numbers.
310       *
311       * <p>The extended BNF grammar is as follows:<br>
312       * <pre>
313       * <em>DecodableString</em>:
314       *      ( [ <code>-</code> ] <em>DecimalNumber</em> )
315       *    | ( [ <code>-</code> ] ( <code>0x</code> | <code>0X</code>
316       *              | <code>#</code> ) <em>HexDigit</em> { <em>HexDigit</em> } )
317       *    | ( [ <code>-</code> ] <code>0</code> { <em>OctalDigit</em> } )
318       * <em>DecimalNumber</em>:
319       *        <em>DecimalDigit except '0'</em> { <em>DecimalDigit</em> }
320       * <em>DecimalDigit</em>:
321       *        <em>Character.digit(d, 10) has value 0 to 9</em>
322       * <em>OctalDigit</em>:
323       *        <em>Character.digit(d, 8) has value 0 to 7</em>
324       * <em>DecimalDigit</em>:
325       *        <em>Character.digit(d, 16) has value 0 to 15</em>
326       * </pre>
327       * Finally, the value must be in the range <code>MIN_VALUE</code> to
328       * <code>MAX_VALUE</code>, or an exception is thrown. Note that you cannot
329       * use a trailing 'l' or 'L', unlike in Java source code.
330       *
331       * @param str the <code>String</code> to interpret
332       * @return the value of the String as a <code>Long</code>
333       * @throws NumberFormatException if <code>s</code> cannot be parsed as a
334       *         <code>long</code>
335       * @throws NullPointerException if <code>s</code> is null
336       * @since 1.2
337       */
338      public static Long decode(String str)
339      {
340        return new Long(parseLong(str, 10, true));
341      }
342    
343      /**
344       * Return the value of this <code>Long</code> as a <code>byte</code>.
345       *
346       * @return the byte value
347       */
348      public byte byteValue()
349      {
350        return (byte) value;
351      }
352    
353      /**
354       * Return the value of this <code>Long</code> as a <code>short</code>.
355       *
356       * @return the short value
357       */
358      public short shortValue()
359      {
360        return (short) value;
361      }
362    
363      /**
364       * Return the value of this <code>Long</code> as an <code>int</code>.
365       *
366       * @return the int value
367       */
368      public int intValue()
369      {
370        return (int) value;
371      }
372    
373      /**
374       * Return the value of this <code>Long</code>.
375       *
376       * @return the long value
377       */
378      public long longValue()
379      {
380        return value;
381      }
382    
383      /**
384       * Return the value of this <code>Long</code> as a <code>float</code>.
385       *
386       * @return the float value
387       */
388      public float floatValue()
389      {
390        return value;
391      }
392    
393      /**
394       * Return the value of this <code>Long</code> as a <code>double</code>.
395       *
396       * @return the double value
397       */
398      public double doubleValue()
399      {
400        return value;
401      }
402    
403      /**
404       * Converts the <code>Long</code> value to a <code>String</code> and
405       * assumes a radix of 10.
406       *
407       * @return the <code>String</code> representation
408       */
409      public String toString()
410      {
411        return toString(value, 10);
412      }
413    
414      /**
415       * Return a hashcode representing this Object. <code>Long</code>'s hash
416       * code is calculated by <code>(int) (value ^ (value &gt;&gt; 32))</code>.
417       *
418       * @return this Object's hash code
419       */
420      public int hashCode()
421      {
422        return (int) (value ^ (value >>> 32));
423      }
424    
425      /**
426       * Returns <code>true</code> if <code>obj</code> is an instance of
427       * <code>Long</code> and represents the same long value.
428       *
429       * @param obj the object to compare
430       * @return whether these Objects are semantically equal
431       */
432      public boolean equals(Object obj)
433      {
434        return obj instanceof Long && value == ((Long) obj).value;
435      }
436    
437      /**
438       * Get the specified system property as a <code>Long</code>. The
439       * <code>decode()</code> method will be used to interpret the value of
440       * the property.
441       *
442       * @param nm the name of the system property
443       * @return the system property as a <code>Long</code>, or null if the
444       *         property is not found or cannot be decoded
445       * @throws SecurityException if accessing the system property is forbidden
446       * @see System#getProperty(String)
447       * @see #decode(String)
448       */
449      public static Long getLong(String nm)
450      {
451        return getLong(nm, null);
452      }
453    
454      /**
455       * Get the specified system property as a <code>Long</code>, or use a
456       * default <code>long</code> value if the property is not found or is not
457       * decodable. The <code>decode()</code> method will be used to interpret
458       * the value of the property.
459       *
460       * @param nm the name of the system property
461       * @param val the default value
462       * @return the value of the system property, or the default
463       * @throws SecurityException if accessing the system property is forbidden
464       * @see System#getProperty(String)
465       * @see #decode(String)
466       */
467      public static Long getLong(String nm, long val)
468      {
469        Long result = getLong(nm, null);
470        return result == null ? new Long(val) : result;
471      }
472    
473      /**
474       * Get the specified system property as a <code>Long</code>, or use a
475       * default <code>Long</code> value if the property is not found or is
476       * not decodable. The <code>decode()</code> method will be used to
477       * interpret the value of the property.
478       *
479       * @param nm the name of the system property
480       * @param def the default value
481       * @return the value of the system property, or the default
482       * @throws SecurityException if accessing the system property is forbidden
483       * @see System#getProperty(String)
484       * @see #decode(String)
485       */
486      public static Long getLong(String nm, Long def)
487      {
488        if (nm == null || "".equals(nm))
489          return def;
490        nm = System.getProperty(nm);
491        if (nm == null)
492          return def;
493        try
494          {
495            return decode(nm);
496          }
497        catch (NumberFormatException e)
498          {
499            return def;
500          }
501      }
502    
503      /**
504       * Compare two Longs numerically by comparing their <code>long</code>
505       * values. The result is positive if the first is greater, negative if the
506       * second is greater, and 0 if the two are equal.
507       *
508       * @param l the Long to compare
509       * @return the comparison
510       * @since 1.2
511       */
512      public int compareTo(Long l)
513      {
514        if (value == l.value)
515          return 0;
516        // Returns just -1 or 1 on inequality; doing math might overflow the long.
517        return value > l.value ? 1 : -1;
518      }
519    
520      /**
521       * Return the number of bits set in x.
522       * @param x value to examine
523       * @since 1.5
524       */
525      public static int bitCount(long x)
526      {
527        // Successively collapse alternating bit groups into a sum.
528        x = ((x >> 1) & 0x5555555555555555L) + (x & 0x5555555555555555L);
529        x = ((x >> 2) & 0x3333333333333333L) + (x & 0x3333333333333333L);
530        int v = (int) ((x >>> 32) + x);
531        v = ((v >> 4) & 0x0f0f0f0f) + (v & 0x0f0f0f0f);
532        v = ((v >> 8) & 0x00ff00ff) + (v & 0x00ff00ff);
533        return ((v >> 16) & 0x0000ffff) + (v & 0x0000ffff);
534      }
535    
536      /**
537       * Rotate x to the left by distance bits.
538       * @param x the value to rotate
539       * @param distance the number of bits by which to rotate
540       * @since 1.5
541       */
542      public static long rotateLeft(long x, int distance)
543      {
544        // This trick works because the shift operators implicitly mask
545        // the shift count.
546        return (x << distance) | (x >>> - distance);
547      }
548    
549      /**
550       * Rotate x to the right by distance bits.
551       * @param x the value to rotate
552       * @param distance the number of bits by which to rotate
553       * @since 1.5
554       */
555      public static long rotateRight(long x, int distance)
556      {
557        // This trick works because the shift operators implicitly mask
558        // the shift count.
559        return (x << - distance) | (x >>> distance);
560      }
561    
562      /**
563       * Find the highest set bit in value, and return a new value
564       * with only that bit set.
565       * @param value the value to examine
566       * @since 1.5
567       */
568      public static long highestOneBit(long value)
569      {
570        value |= value >>> 1;
571        value |= value >>> 2;
572        value |= value >>> 4;
573        value |= value >>> 8;
574        value |= value >>> 16;
575        value |= value >>> 32;
576        return value ^ (value >>> 1);
577      }
578    
579      /**
580       * Return the number of leading zeros in value.
581       * @param value the value to examine
582       * @since 1.5
583       */
584      public static int numberOfLeadingZeros(long value)
585      {
586        value |= value >>> 1;
587        value |= value >>> 2;
588        value |= value >>> 4;
589        value |= value >>> 8;
590        value |= value >>> 16;
591        value |= value >>> 32;
592        return bitCount(~value);
593      }
594    
595      /**
596       * Find the lowest set bit in value, and return a new value
597       * with only that bit set.
598       * @param value the value to examine
599       * @since 1.5
600       */
601      public static long lowestOneBit(long value)
602      {
603        // Classic assembly trick.
604        return value & - value;
605      }
606    
607      /**
608       * Find the number of trailing zeros in value.
609       * @param value the value to examine
610       * @since 1.5
611       */
612      public static int numberOfTrailingZeros(long value)
613      {
614        return bitCount((value & -value) - 1);
615      }
616    
617      /**
618       * Return 1 if x is positive, -1 if it is negative, and 0 if it is
619       * zero.
620       * @param x the value to examine
621       * @since 1.5
622       */
623      public static int signum(long x)
624      {
625        return x < 0 ? -1 : (x > 0 ? 1 : 0);
626      }
627    
628      /**
629       * Reverse the bytes in val.
630       * @since 1.5
631       */
632      public static long reverseBytes(long val)
633      {
634        int hi = Integer.reverseBytes((int) val);
635        int lo = Integer.reverseBytes((int) (val >>> 32));
636        return (((long) hi) << 32) | lo;
637      }
638    
639      /**
640       * Reverse the bits in val.
641       * @since 1.5
642       */
643      public static long reverse(long val)
644      {
645        long hi = Integer.reverse((int) val) & 0xffffffffL;
646        long lo = Integer.reverse((int) (val >>> 32)) & 0xffffffffL;
647        return (hi << 32) | lo;
648      }
649    
650      /**
651       * Helper for converting unsigned numbers to String.
652       *
653       * @param num the number
654       * @param exp log2(digit) (ie. 1, 3, or 4 for binary, oct, hex)
655       */
656      private static String toUnsignedString(long num, int exp)
657      {
658        // Use the Integer toUnsignedString for efficiency if possible.
659        // If NUM<0 then this particular optimization doesn't work
660        // properly.
661        if (num >= 0 && (int) num == num)
662          return Integer.toUnsignedString((int) num, exp);
663    
664        // Use an array large enough for a binary number.
665        int mask = (1 << exp) - 1;
666        char[] buffer = new char[64];
667        int i = 64;
668        do
669          {
670            buffer[--i] = digits[(int) num & mask];
671            num >>>= exp;
672          }
673        while (num != 0);
674    
675        // Package constructor avoids an array copy.
676        return new String(buffer, i, 64 - i, true);
677      }
678    
679      /**
680       * Helper for parsing longs.
681       *
682       * @param str the string to parse
683       * @param radix the radix to use, must be 10 if decode is true
684       * @param decode if called from decode
685       * @return the parsed long value
686       * @throws NumberFormatException if there is an error
687       * @throws NullPointerException if decode is true and str is null
688       * @see #parseLong(String, int)
689       * @see #decode(String)
690       */
691      private static long parseLong(String str, int radix, boolean decode)
692      {
693        if (! decode && str == null)
694          throw new NumberFormatException();
695        int index = 0;
696        int len = str.length();
697        boolean isNeg = false;
698        if (len == 0)
699          throw new NumberFormatException();
700        int ch = str.charAt(index);
701        if (ch == '-')
702          {
703            if (len == 1)
704              throw new NumberFormatException();
705            isNeg = true;
706            ch = str.charAt(++index);
707          }
708        if (decode)
709          {
710            if (ch == '0')
711              {
712                if (++index == len)
713                  return 0;
714                if ((str.charAt(index) & ~('x' ^ 'X')) == 'X')
715                  {
716                    radix = 16;
717                    index++;
718                  }
719                else
720                  radix = 8;
721              }
722            else if (ch == '#')
723              {
724                radix = 16;
725                index++;
726              }
727          }
728        if (index == len)
729          throw new NumberFormatException();
730    
731        long max = MAX_VALUE / radix;
732        // We can't directly write `max = (MAX_VALUE + 1) / radix'.
733        // So instead we fake it.
734        if (isNeg && MAX_VALUE % radix == radix - 1)
735          ++max;
736    
737        long val = 0;
738        while (index < len)
739          {
740            if (val < 0 || val > max)
741              throw new NumberFormatException();
742    
743            ch = Character.digit(str.charAt(index++), radix);
744            val = val * radix + ch;
745            if (ch < 0 || (val < 0 && (! isNeg || val != MIN_VALUE)))
746              throw new NumberFormatException();
747          }
748        return isNeg ? -val : val;
749      }
750    }