001/*
002 * Copyright (C) 2008 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
005 * in compliance with the License. You may obtain a copy of the License at
006 *
007 * http://www.apache.org/licenses/LICENSE-2.0
008 *
009 * Unless required by applicable law or agreed to in writing, software distributed under the License
010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
011 * or implied. See the License for the specific language governing permissions and limitations under
012 * the License.
013 */
014
015package com.google.common.primitives;
016
017import static com.google.common.base.Preconditions.checkArgument;
018import static com.google.common.base.Preconditions.checkElementIndex;
019import static com.google.common.base.Preconditions.checkNotNull;
020import static com.google.common.base.Preconditions.checkPositionIndexes;
021
022import com.google.common.annotations.Beta;
023import com.google.common.annotations.GwtCompatible;
024import com.google.common.base.Converter;
025import java.io.Serializable;
026import java.util.AbstractList;
027import java.util.Arrays;
028import java.util.Collection;
029import java.util.Collections;
030import java.util.Comparator;
031import java.util.List;
032import java.util.RandomAccess;
033import javax.annotation.CheckForNull;
034import javax.annotation.Nullable;
035
036/**
037 * Static utility methods pertaining to {@code long} primitives, that are not already found in
038 * either {@link Long} or {@link Arrays}.
039 *
040 * <p>See the Guava User Guide article on
041 * <a href="https://github.com/google/guava/wiki/PrimitivesExplained">primitive utilities</a>.
042 *
043 * @author Kevin Bourrillion
044 * @since 1.0
045 */
046@GwtCompatible
047public final class Longs {
048  private Longs() {}
049
050  /**
051   * The number of bytes required to represent a primitive {@code long} value.
052   *
053   * <p><b>Java 8 users:</b> use {@link Long#BYTES} instead.
054   */
055  public static final int BYTES = Long.SIZE / Byte.SIZE;
056
057  /**
058   * The largest power of two that can be represented as a {@code long}.
059   *
060   * @since 10.0
061   */
062  public static final long MAX_POWER_OF_TWO = 1L << (Long.SIZE - 2);
063
064  /**
065   * Returns a hash code for {@code value}; equal to the result of invoking
066   * {@code ((Long) value).hashCode()}.
067   *
068   * <p>This method always return the value specified by {@link Long#hashCode()} in java, which
069   * might be different from {@code ((Long) value).hashCode()} in GWT because
070   * {@link Long#hashCode()} in GWT does not obey the JRE contract.
071   *
072   * <p><b>Java 8 users:</b> use {@link Long#hashCode(long)} instead.
073   *
074   * @param value a primitive {@code long} value
075   * @return a hash code for the value
076   */
077  public static int hashCode(long value) {
078    return (int) (value ^ (value >>> 32));
079  }
080
081  /**
082   * Compares the two specified {@code long} values. The sign of the value returned is the same as
083   * that of {@code ((Long) a).compareTo(b)}.
084   *
085   * <p><b>Note for Java 7 and later:</b> this method should be treated as deprecated; use the
086   * equivalent {@link Long#compare} method instead.
087   *
088   * @param a the first {@code long} to compare
089   * @param b the second {@code long} to compare
090   * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is
091   *     greater than {@code b}; or zero if they are equal
092   */
093  public static int compare(long a, long b) {
094    return (a < b) ? -1 : ((a > b) ? 1 : 0);
095  }
096
097  /**
098   * Returns {@code true} if {@code target} is present as an element anywhere in {@code array}.
099   *
100   * @param array an array of {@code long} values, possibly empty
101   * @param target a primitive {@code long} value
102   * @return {@code true} if {@code array[i] == target} for some value of {@code
103   *     i}
104   */
105  public static boolean contains(long[] array, long target) {
106    for (long value : array) {
107      if (value == target) {
108        return true;
109      }
110    }
111    return false;
112  }
113
114  /**
115   * Returns the index of the first appearance of the value {@code target} in {@code array}.
116   *
117   * @param array an array of {@code long} values, possibly empty
118   * @param target a primitive {@code long} value
119   * @return the least index {@code i} for which {@code array[i] == target}, or {@code -1} if no
120   *     such index exists.
121   */
122  public static int indexOf(long[] array, long target) {
123    return indexOf(array, target, 0, array.length);
124  }
125
126  // TODO(kevinb): consider making this public
127  private static int indexOf(long[] array, long target, int start, int end) {
128    for (int i = start; i < end; i++) {
129      if (array[i] == target) {
130        return i;
131      }
132    }
133    return -1;
134  }
135
136  /**
137   * Returns the start position of the first occurrence of the specified {@code
138   * target} within {@code array}, or {@code -1} if there is no such occurrence.
139   *
140   * <p>More formally, returns the lowest index {@code i} such that
141   * {@code Arrays.copyOfRange(array, i, i + target.length)} contains exactly the same elements as
142   * {@code target}.
143   *
144   * @param array the array to search for the sequence {@code target}
145   * @param target the array to search for as a sub-sequence of {@code array}
146   */
147  public static int indexOf(long[] array, long[] target) {
148    checkNotNull(array, "array");
149    checkNotNull(target, "target");
150    if (target.length == 0) {
151      return 0;
152    }
153
154    outer:
155    for (int i = 0; i < array.length - target.length + 1; i++) {
156      for (int j = 0; j < target.length; j++) {
157        if (array[i + j] != target[j]) {
158          continue outer;
159        }
160      }
161      return i;
162    }
163    return -1;
164  }
165
166  /**
167   * Returns the index of the last appearance of the value {@code target} in {@code array}.
168   *
169   * @param array an array of {@code long} values, possibly empty
170   * @param target a primitive {@code long} value
171   * @return the greatest index {@code i} for which {@code array[i] == target}, or {@code -1} if no
172   *     such index exists.
173   */
174  public static int lastIndexOf(long[] array, long target) {
175    return lastIndexOf(array, target, 0, array.length);
176  }
177
178  // TODO(kevinb): consider making this public
179  private static int lastIndexOf(long[] array, long target, int start, int end) {
180    for (int i = end - 1; i >= start; i--) {
181      if (array[i] == target) {
182        return i;
183      }
184    }
185    return -1;
186  }
187
188  /**
189   * Returns the least value present in {@code array}.
190   *
191   * @param array a <i>nonempty</i> array of {@code long} values
192   * @return the value present in {@code array} that is less than or equal to every other value in
193   *     the array
194   * @throws IllegalArgumentException if {@code array} is empty
195   */
196  public static long min(long... array) {
197    checkArgument(array.length > 0);
198    long min = array[0];
199    for (int i = 1; i < array.length; i++) {
200      if (array[i] < min) {
201        min = array[i];
202      }
203    }
204    return min;
205  }
206
207  /**
208   * Returns the greatest value present in {@code array}.
209   *
210   * @param array a <i>nonempty</i> array of {@code long} values
211   * @return the value present in {@code array} that is greater than or equal to every other value
212   *     in the array
213   * @throws IllegalArgumentException if {@code array} is empty
214   */
215  public static long max(long... array) {
216    checkArgument(array.length > 0);
217    long max = array[0];
218    for (int i = 1; i < array.length; i++) {
219      if (array[i] > max) {
220        max = array[i];
221      }
222    }
223    return max;
224  }
225
226  /**
227   * Returns the value nearest to {@code value} which is within the closed range {@code [min..max]}.
228   *
229   * <p>If {@code value} is within the range {@code [min..max]}, {@code value} is returned
230   * unchanged. If {@code value} is less than {@code min}, {@code min} is returned, and if
231   * {@code value} is greater than {@code max}, {@code max} is returned.
232   *
233   * @param value the {@code long} value to constrain
234   * @param min the lower bound (inclusive) of the range to constrain {@code value} to
235   * @param max the upper bound (inclusive) of the range to constrain {@code value} to
236   * @throws IllegalArgumentException if {@code min > max}
237   * @since 21.0
238   */
239  @Beta
240  public static long constrainToRange(long value, long min, long max) {
241    checkArgument(min <= max, "min (%s) must be less than or equal to max (%s)", min, max);
242    return Math.min(Math.max(value, min), max);
243  }
244
245  /**
246   * Returns the values from each provided array combined into a single array. For example,
247   * {@code concat(new long[] {a, b}, new long[] {}, new long[] {c}} returns the array
248   * {@code {a, b, c}}.
249   *
250   * @param arrays zero or more {@code long} arrays
251   * @return a single array containing all the values from the source arrays, in order
252   */
253  public static long[] concat(long[]... arrays) {
254    int length = 0;
255    for (long[] array : arrays) {
256      length += array.length;
257    }
258    long[] result = new long[length];
259    int pos = 0;
260    for (long[] array : arrays) {
261      System.arraycopy(array, 0, result, pos, array.length);
262      pos += array.length;
263    }
264    return result;
265  }
266
267  /**
268   * Returns a big-endian representation of {@code value} in an 8-element byte array; equivalent to
269   * {@code ByteBuffer.allocate(8).putLong(value).array()}. For example, the input value
270   * {@code 0x1213141516171819L} would yield the byte array {@code {0x12, 0x13, 0x14, 0x15, 0x16,
271   * 0x17, 0x18, 0x19}}.
272   *
273   * <p>If you need to convert and concatenate several values (possibly even of different types),
274   * use a shared {@link java.nio.ByteBuffer} instance, or use
275   * {@link com.google.common.io.ByteStreams#newDataOutput()} to get a growable buffer.
276   */
277  public static byte[] toByteArray(long value) {
278    // Note that this code needs to stay compatible with GWT, which has known
279    // bugs when narrowing byte casts of long values occur.
280    byte[] result = new byte[8];
281    for (int i = 7; i >= 0; i--) {
282      result[i] = (byte) (value & 0xffL);
283      value >>= 8;
284    }
285    return result;
286  }
287
288  /**
289   * Returns the {@code long} value whose big-endian representation is stored in the first 8 bytes
290   * of {@code bytes}; equivalent to {@code ByteBuffer.wrap(bytes).getLong()}. For example, the
291   * input byte array {@code {0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19}} would yield the
292   * {@code long} value {@code 0x1213141516171819L}.
293   *
294   * <p>Arguably, it's preferable to use {@link java.nio.ByteBuffer}; that library exposes much more
295   * flexibility at little cost in readability.
296   *
297   * @throws IllegalArgumentException if {@code bytes} has fewer than 8 elements
298   */
299  public static long fromByteArray(byte[] bytes) {
300    checkArgument(bytes.length >= BYTES, "array too small: %s < %s", bytes.length, BYTES);
301    return fromBytes(
302        bytes[0], bytes[1], bytes[2], bytes[3], bytes[4], bytes[5], bytes[6], bytes[7]);
303  }
304
305  /**
306   * Returns the {@code long} value whose byte representation is the given 8 bytes, in big-endian
307   * order; equivalent to {@code Longs.fromByteArray(new byte[] {b1, b2, b3, b4, b5, b6, b7, b8})}.
308   *
309   * @since 7.0
310   */
311  public static long fromBytes(
312      byte b1, byte b2, byte b3, byte b4, byte b5, byte b6, byte b7, byte b8) {
313    return (b1 & 0xFFL) << 56
314        | (b2 & 0xFFL) << 48
315        | (b3 & 0xFFL) << 40
316        | (b4 & 0xFFL) << 32
317        | (b5 & 0xFFL) << 24
318        | (b6 & 0xFFL) << 16
319        | (b7 & 0xFFL) << 8
320        | (b8 & 0xFFL);
321  }
322
323  /*
324   * Moving asciiDigits into this static holder class lets ProGuard eliminate and inline the Longs
325   * class.
326   */
327  static final class AsciiDigits {
328    private AsciiDigits() {}
329
330    private static final byte[] asciiDigits;
331
332    static {
333      byte[] result = new byte[128];
334      Arrays.fill(result, (byte) -1);
335      for (int i = 0; i <= 9; i++) {
336        result['0' + i] = (byte) i;
337      }
338      for (int i = 0; i <= 26; i++) {
339        result['A' + i] = (byte) (10 + i);
340        result['a' + i] = (byte) (10 + i);
341      }
342      asciiDigits = result;
343    }
344
345    static int digit(char c) {
346      return (c < 128) ? asciiDigits[c] : -1;
347    }
348  }
349
350  /**
351   * Parses the specified string as a signed decimal long value. The ASCII character {@code '-'}
352   * (<code>'&#92;u002D'</code>) is recognized as the minus sign.
353   *
354   * <p>Unlike {@link Long#parseLong(String)}, this method returns {@code null} instead of throwing
355   * an exception if parsing fails. Additionally, this method only accepts ASCII digits, and returns
356   * {@code null} if non-ASCII digits are present in the string.
357   *
358   * <p>Note that strings prefixed with ASCII {@code '+'} are rejected, even under JDK 7, despite
359   * the change to {@link Long#parseLong(String)} for that version.
360   *
361   * @param string the string representation of a long value
362   * @return the long value represented by {@code string}, or {@code null} if {@code string} has a
363   *     length of zero or cannot be parsed as a long value
364   * @since 14.0
365   */
366  @Beta
367  @Nullable
368  @CheckForNull
369  public static Long tryParse(String string) {
370    return tryParse(string, 10);
371  }
372
373  /**
374   * Parses the specified string as a signed long value using the specified radix. The ASCII
375   * character {@code '-'} (<code>'&#92;u002D'</code>) is recognized as the minus sign.
376   *
377   * <p>Unlike {@link Long#parseLong(String, int)}, this method returns {@code null} instead of
378   * throwing an exception if parsing fails. Additionally, this method only accepts ASCII digits,
379   * and returns {@code null} if non-ASCII digits are present in the string.
380   *
381   * <p>Note that strings prefixed with ASCII {@code '+'} are rejected, even under JDK 7, despite
382   * the change to {@link Long#parseLong(String, int)} for that version.
383   *
384   * @param string the string representation of an long value
385   * @param radix the radix to use when parsing
386   * @return the long value represented by {@code string} using {@code radix}, or {@code null} if
387   *     {@code string} has a length of zero or cannot be parsed as a long value
388   * @throws IllegalArgumentException if {@code radix < Character.MIN_RADIX} or
389   *     {@code radix > Character.MAX_RADIX}
390   * @since 19.0
391   */
392  @Beta
393  @Nullable
394  @CheckForNull
395  public static Long tryParse(String string, int radix) {
396    if (checkNotNull(string).isEmpty()) {
397      return null;
398    }
399    if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX) {
400      throw new IllegalArgumentException(
401          "radix must be between MIN_RADIX and MAX_RADIX but was " + radix);
402    }
403    boolean negative = string.charAt(0) == '-';
404    int index = negative ? 1 : 0;
405    if (index == string.length()) {
406      return null;
407    }
408    int digit = AsciiDigits.digit(string.charAt(index++));
409    if (digit < 0 || digit >= radix) {
410      return null;
411    }
412    long accum = -digit;
413
414    long cap = Long.MIN_VALUE / radix;
415
416    while (index < string.length()) {
417      digit = AsciiDigits.digit(string.charAt(index++));
418      if (digit < 0 || digit >= radix || accum < cap) {
419        return null;
420      }
421      accum *= radix;
422      if (accum < Long.MIN_VALUE + digit) {
423        return null;
424      }
425      accum -= digit;
426    }
427
428    if (negative) {
429      return accum;
430    } else if (accum == Long.MIN_VALUE) {
431      return null;
432    } else {
433      return -accum;
434    }
435  }
436
437  private static final class LongConverter extends Converter<String, Long> implements Serializable {
438    static final LongConverter INSTANCE = new LongConverter();
439
440    @Override
441    protected Long doForward(String value) {
442      return Long.decode(value);
443    }
444
445    @Override
446    protected String doBackward(Long value) {
447      return value.toString();
448    }
449
450    @Override
451    public String toString() {
452      return "Longs.stringConverter()";
453    }
454
455    private Object readResolve() {
456      return INSTANCE;
457    }
458
459    private static final long serialVersionUID = 1;
460  }
461
462  /**
463   * Returns a serializable converter object that converts between strings and longs using
464   * {@link Long#decode} and {@link Long#toString()}. The returned converter throws
465   * {@link NumberFormatException} if the input string is invalid.
466   *
467   * <p><b>Warning:</b> please see {@link Long#decode} to understand exactly how strings are parsed.
468   * For example, the string {@code "0123"} is treated as <i>octal</i> and converted to the value
469   * {@code 83L}.
470   *
471   * @since 16.0
472   */
473  @Beta
474  public static Converter<String, Long> stringConverter() {
475    return LongConverter.INSTANCE;
476  }
477
478  /**
479   * Returns an array containing the same values as {@code array}, but guaranteed to be of a
480   * specified minimum length. If {@code array} already has a length of at least {@code minLength},
481   * it is returned directly. Otherwise, a new array of size {@code minLength + padding} is
482   * returned, containing the values of {@code array}, and zeroes in the remaining places.
483   *
484   * @param array the source array
485   * @param minLength the minimum length the returned array must guarantee
486   * @param padding an extra amount to "grow" the array by if growth is necessary
487   * @throws IllegalArgumentException if {@code minLength} or {@code padding} is negative
488   * @return an array containing the values of {@code array}, with guaranteed minimum length
489   *     {@code minLength}
490   */
491  public static long[] ensureCapacity(long[] array, int minLength, int padding) {
492    checkArgument(minLength >= 0, "Invalid minLength: %s", minLength);
493    checkArgument(padding >= 0, "Invalid padding: %s", padding);
494    return (array.length < minLength) ? Arrays.copyOf(array, minLength + padding) : array;
495  }
496
497  /**
498   * Returns a string containing the supplied {@code long} values separated by {@code separator}.
499   * For example, {@code join("-", 1L, 2L, 3L)} returns the string {@code "1-2-3"}.
500   *
501   * @param separator the text that should appear between consecutive values in the resulting string
502   *     (but not at the start or end)
503   * @param array an array of {@code long} values, possibly empty
504   */
505  public static String join(String separator, long... array) {
506    checkNotNull(separator);
507    if (array.length == 0) {
508      return "";
509    }
510
511    // For pre-sizing a builder, just get the right order of magnitude
512    StringBuilder builder = new StringBuilder(array.length * 10);
513    builder.append(array[0]);
514    for (int i = 1; i < array.length; i++) {
515      builder.append(separator).append(array[i]);
516    }
517    return builder.toString();
518  }
519
520  /**
521   * Returns a comparator that compares two {@code long} arrays <a
522   * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it
523   * compares, using {@link #compare(long, long)}), the first pair of values that follow any common
524   * prefix, or when one array is a prefix of the other, treats the shorter array as the lesser. For
525   * example, {@code [] < [1L] < [1L, 2L] < [2L]}.
526   *
527   * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays
528   * support only identity equality), but it is consistent with
529   * {@link Arrays#equals(long[], long[])}.
530   *
531   * @since 2.0
532   */
533  public static Comparator<long[]> lexicographicalComparator() {
534    return LexicographicalComparator.INSTANCE;
535  }
536
537  private enum LexicographicalComparator implements Comparator<long[]> {
538    INSTANCE;
539
540    @Override
541    public int compare(long[] left, long[] right) {
542      int minLength = Math.min(left.length, right.length);
543      for (int i = 0; i < minLength; i++) {
544        int result = Longs.compare(left[i], right[i]);
545        if (result != 0) {
546          return result;
547        }
548      }
549      return left.length - right.length;
550    }
551
552    @Override
553    public String toString() {
554      return "Longs.lexicographicalComparator()";
555    }
556  }
557
558  /**
559   * Returns an array containing each value of {@code collection}, converted to a {@code long} value
560   * in the manner of {@link Number#longValue}.
561   *
562   * <p>Elements are copied from the argument collection as if by {@code
563   * collection.toArray()}. Calling this method is as thread-safe as calling that method.
564   *
565   * @param collection a collection of {@code Number} instances
566   * @return an array containing the same values as {@code collection}, in the same order, converted
567   *     to primitives
568   * @throws NullPointerException if {@code collection} or any of its elements is null
569   * @since 1.0 (parameter was {@code Collection<Long>} before 12.0)
570   */
571  public static long[] toArray(Collection<? extends Number> collection) {
572    if (collection instanceof LongArrayAsList) {
573      return ((LongArrayAsList) collection).toLongArray();
574    }
575
576    Object[] boxedArray = collection.toArray();
577    int len = boxedArray.length;
578    long[] array = new long[len];
579    for (int i = 0; i < len; i++) {
580      // checkNotNull for GWT (do not optimize)
581      array[i] = ((Number) checkNotNull(boxedArray[i])).longValue();
582    }
583    return array;
584  }
585
586  /**
587   * Returns a fixed-size list backed by the specified array, similar to
588   * {@link Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any
589   * attempt to set a value to {@code null} will result in a {@link NullPointerException}.
590   *
591   * <p>The returned list maintains the values, but not the identities, of {@code Long} objects
592   * written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for
593   * the returned list is unspecified.
594   *
595   * @param backingArray the array to back the list
596   * @return a list view of the array
597   */
598  public static List<Long> asList(long... backingArray) {
599    if (backingArray.length == 0) {
600      return Collections.emptyList();
601    }
602    return new LongArrayAsList(backingArray);
603  }
604
605  @GwtCompatible
606  private static class LongArrayAsList extends AbstractList<Long>
607      implements RandomAccess, Serializable {
608    final long[] array;
609    final int start;
610    final int end;
611
612    LongArrayAsList(long[] array) {
613      this(array, 0, array.length);
614    }
615
616    LongArrayAsList(long[] array, int start, int end) {
617      this.array = array;
618      this.start = start;
619      this.end = end;
620    }
621
622    @Override
623    public int size() {
624      return end - start;
625    }
626
627    @Override
628    public boolean isEmpty() {
629      return false;
630    }
631
632    @Override
633    public Long get(int index) {
634      checkElementIndex(index, size());
635      return array[start + index];
636    }
637
638    @Override
639    public boolean contains(Object target) {
640      // Overridden to prevent a ton of boxing
641      return (target instanceof Long) && Longs.indexOf(array, (Long) target, start, end) != -1;
642    }
643
644    @Override
645    public int indexOf(Object target) {
646      // Overridden to prevent a ton of boxing
647      if (target instanceof Long) {
648        int i = Longs.indexOf(array, (Long) target, start, end);
649        if (i >= 0) {
650          return i - start;
651        }
652      }
653      return -1;
654    }
655
656    @Override
657    public int lastIndexOf(Object target) {
658      // Overridden to prevent a ton of boxing
659      if (target instanceof Long) {
660        int i = Longs.lastIndexOf(array, (Long) target, start, end);
661        if (i >= 0) {
662          return i - start;
663        }
664      }
665      return -1;
666    }
667
668    @Override
669    public Long set(int index, Long element) {
670      checkElementIndex(index, size());
671      long oldValue = array[start + index];
672      // checkNotNull for GWT (do not optimize)
673      array[start + index] = checkNotNull(element);
674      return oldValue;
675    }
676
677    @Override
678    public List<Long> subList(int fromIndex, int toIndex) {
679      int size = size();
680      checkPositionIndexes(fromIndex, toIndex, size);
681      if (fromIndex == toIndex) {
682        return Collections.emptyList();
683      }
684      return new LongArrayAsList(array, start + fromIndex, start + toIndex);
685    }
686
687    @Override
688    public boolean equals(@Nullable Object object) {
689      if (object == this) {
690        return true;
691      }
692      if (object instanceof LongArrayAsList) {
693        LongArrayAsList that = (LongArrayAsList) object;
694        int size = size();
695        if (that.size() != size) {
696          return false;
697        }
698        for (int i = 0; i < size; i++) {
699          if (array[start + i] != that.array[that.start + i]) {
700            return false;
701          }
702        }
703        return true;
704      }
705      return super.equals(object);
706    }
707
708    @Override
709    public int hashCode() {
710      int result = 1;
711      for (int i = start; i < end; i++) {
712        result = 31 * result + Longs.hashCode(array[i]);
713      }
714      return result;
715    }
716
717    @Override
718    public String toString() {
719      StringBuilder builder = new StringBuilder(size() * 10);
720      builder.append('[').append(array[start]);
721      for (int i = start + 1; i < end; i++) {
722        builder.append(", ").append(array[i]);
723      }
724      return builder.append(']').toString();
725    }
726
727    long[] toLongArray() {
728      return Arrays.copyOfRange(array, start, end);
729    }
730
731    private static final long serialVersionUID = 0;
732  }
733}