Package org.apache.lucene.util

# Class ArrayUtil

java.lang.Object
org.apache.lucene.util.ArrayUtil

public final class ArrayUtil extends Object
Methods for manipulating arrays.

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Class
  Description
  `static interface`
  `ArrayUtil.ByteArrayComparator`
  Comparator for a fixed number of bytes.

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `static final int`
  `MAX_ARRAY_LENGTH`
  Maximum length for an array (Integer.MAX_VALUE - RamUsageEstimator.NUM_BYTES_ARRAY_HEADER).

- ## Method Summary

  Modifier and Type
  Method
  Description
  `static int`
  `compareUnsigned4(byte[] a, int aOffset, byte[] b, int bOffset)`
  Compare exactly 4 unsigned bytes from the provided arrays.
  `static int`
  `compareUnsigned8(byte[] a, int aOffset, byte[] b, int bOffset)`
  Compare exactly 8 unsigned bytes from the provided arrays.
  `static byte[]`
  `copyArray(byte[] array)`
  Copies an array into a new array.
  `static char[]`
  `copyArray(char[] array)`
  Copies an array into a new array.
  `static double[]`
  `copyArray(double[] array)`
  Copies an array into a new array.
  `static float[]`
  `copyArray(float[] array)`
  Copies an array into a new array.
  `static int[]`
  `copyArray(int[] array)`
  Copies an array into a new array.
  `static long[]`
  `copyArray(long[] array)`
  Copies an array into a new array.
  `static short[]`
  `copyArray(short[] array)`
  Copies an array into a new array.
  `static <T> T[]`
  `copyArray(T[] array)`
  Copies an array into a new array.
  `static byte[]`
  `copyOfSubArray(byte[] array, int from, int to)`
  Copies the specified range of the given array into a new sub array.
  `static char[]`
  `copyOfSubArray(char[] array, int from, int to)`
  Copies the specified range of the given array into a new sub array.
  `static double[]`
  `copyOfSubArray(double[] array, int from, int to)`
  Copies the specified range of the given array into a new sub array.
  `static float[]`
  `copyOfSubArray(float[] array, int from, int to)`
  Copies the specified range of the given array into a new sub array.
  `static int[]`
  `copyOfSubArray(int[] array, int from, int to)`
  Copies the specified range of the given array into a new sub array.
  `static long[]`
  `copyOfSubArray(long[] array, int from, int to)`
  Copies the specified range of the given array into a new sub array.
  `static short[]`
  `copyOfSubArray(short[] array, int from, int to)`
  Copies the specified range of the given array into a new sub array.
  `static <T> T[]`
  `copyOfSubArray(T[] array, int from, int to)`
  Copies the specified range of the given array into a new sub array.
  `static ArrayUtil.ByteArrayComparator`
  `getUnsignedComparator(int numBytes)`
  Return a comparator for exactly the specified number of bytes.
  `static byte[]`
  `grow(byte[] array)`
  Returns a larger array, generally over-allocating exponentially
  `static byte[]`
  `grow(byte[] array, int minSize)`
  Returns an array whose size is at least `minSize`, generally over-allocating exponentially
  `static char[]`
  `grow(char[] array)`
  Returns a larger array, generally over-allocating exponentially
  `static char[]`
  `grow(char[] array, int minSize)`
  Returns an array whose size is at least `minSize`, generally over-allocating exponentially
  `static double[]`
  `grow(double[] array)`
  Returns a larger array, generally over-allocating exponentially
  `static double[]`
  `grow(double[] array, int minSize)`
  Returns an array whose size is at least `minSize`, generally over-allocating exponentially
  `static float[]`
  `grow(float[] array)`
  Returns a larger array, generally over-allocating exponentially
  `static float[]`
  `grow(float[] array, int minSize)`
  Returns an array whose size is at least `minSize`, generally over-allocating exponentially
  `static int[]`
  `grow(int[] array)`
  Returns a larger array, generally over-allocating exponentially
  `static int[]`
  `grow(int[] array, int minSize)`
  Returns an array whose size is at least `minSize`, generally over-allocating exponentially
  `static long[]`
  `grow(long[] array)`
  Returns a larger array, generally over-allocating exponentially
  `static long[]`
  `grow(long[] array, int minSize)`
  Returns an array whose size is at least `minSize`, generally over-allocating exponentially
  `static short[]`
  `grow(short[] array)`
  Returns a larger array, generally over-allocating exponentially
  `static short[]`
  `grow(short[] array, int minSize)`
  Returns an array whose size is at least `minSize`, generally over-allocating exponentially
  `static <T> T[]`
  `grow(T[] array)`
  Returns a larger array, generally over-allocating exponentially
  `static <T> T[]`
  `grow(T[] array, int minSize)`
  Returns an array whose size is at least `minSize`, generally over-allocating exponentially
  `static byte[]`
  `growExact(byte[] array, int newLength)`
  Returns a new array whose size is exact the specified `newLength` without over-allocating
  `static char[]`
  `growExact(char[] array, int newLength)`
  Returns a new array whose size is exact the specified `newLength` without over-allocating
  `static double[]`
  `growExact(double[] array, int newLength)`
  Returns a new array whose size is exact the specified `newLength` without over-allocating
  `static float[]`
  `growExact(float[] array, int newLength)`
  Returns a new array whose size is exact the specified `newLength` without over-allocating
  `static int[]`
  `growExact(int[] array, int newLength)`
  Returns a new array whose size is exact the specified `newLength` without over-allocating
  `static long[]`
  `growExact(long[] array, int newLength)`
  Returns a new array whose size is exact the specified `newLength` without over-allocating
  `static short[]`
  `growExact(short[] array, int newLength)`
  Returns a new array whose size is exact the specified `newLength` without over-allocating
  `static <T> T[]`
  `growExact(T[] array, int newLength)`
  Returns a new array whose size is exact the specified `newLength` without over-allocating
  `static float[]`
  `growInRange(float[] array, int minLength, int maxLength)`
  Returns an array whose size is at least `minLength` but not over `maxLength`, growing exponentially if it needs to grow.
  `static int[]`
  `growInRange(int[] array, int minLength, int maxLength)`
  Returns an array whose size is at least `minLength`, generally over-allocating exponentially, but never allocating more than `maxLength` elements.
  `static byte[]`
  `growNoCopy(byte[] array, int minSize)`
  Returns an array whose size is at least `minSize`, generally over-allocating exponentially, and it will not copy the origin data to the new array
  `static int[]`
  `growNoCopy(int[] array, int minSize)`
  Returns an array whose size is at least `minSize`, generally over-allocating exponentially, and it will not copy the origin data to the new array
  `static long[]`
  `growNoCopy(long[] array, int minSize)`
  Returns an array whose size is at least `minSize`, generally over-allocating exponentially, and it will not copy the origin data to the new array
  `static int`
  `hashCode(char[] array, int start, int end)`
  Returns hash of chars in range start (inclusive) to end (inclusive)
  `static <T extends Comparable<? super T>>
  void`
  `introSort(T[] a)`
  Sorts the given array in natural order.
  `static <T extends Comparable<? super T>>
  void`
  `introSort(T[] a, int fromIndex, int toIndex)`
  Sorts the given array slice in natural order.
  `static <T> void`
  `introSort(T[] a, int fromIndex, int toIndex, Comparator<? super T> comp)`
  Sorts the given array slice using the `Comparator`.
  `static <T> void`
  `introSort(T[] a, Comparator<? super T> comp)`
  Sorts the given array using the `Comparator`.
  `static int`
  `oversize(int minTargetSize, int bytesPerElement)`
  Returns an array size >= minTargetSize, generally over-allocating exponentially to achieve amortized linear-time cost as the array grows.
  `static int`
  `parseInt(char[] chars, int offset, int len)`
  Parses a char array into an int.
  `static int`
  `parseInt(char[] chars, int offset, int len, int radix)`
  Parses the string argument as if it was an int value and returns the result.
  `static <T> void`
  `select(T[] arr, int from, int to, int k, Comparator<? super T> comparator)`
  Reorganize `arr[from:to[` so that the element at offset k is at the same position as if `arr[from:to]` was sorted, and all elements on its left are less than or equal to it, and all elements on its right are greater than or equal to it.
  `static <T> void`
  `swap(T[] arr, int i, int j)`
  Swap values stored in slots `i` and `j`
  `static <T extends Comparable<? super T>>
  void`
  `timSort(T[] a)`
  Sorts the given array in natural order.
  `static <T extends Comparable<? super T>>
  void`
  `timSort(T[] a, int fromIndex, int toIndex)`
  Sorts the given array slice in natural order.
  `static <T> void`
  `timSort(T[] a, int fromIndex, int toIndex, Comparator<? super T> comp)`
  Sorts the given array slice using the `Comparator`.
  `static <T> void`
  `timSort(T[] a, Comparator<? super T> comp)`
  Sorts the given array using the `Comparator`.

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Field Details

  - ### MAX_ARRAY_LENGTH

    public static final int MAX_ARRAY_LENGTH
    Maximum length for an array (Integer.MAX_VALUE - RamUsageEstimator.NUM_BYTES_ARRAY_HEADER).

- ## Method Details

  - ### parseInt

    public static int parseInt(char[] chars, int offset, int len) throws NumberFormatException
    Parses a char array into an int.
    Parameters:
      `chars` - the character array
      `offset` - The offset into the array
      `len` - The length
    Returns:
      the int
    Throws:
      `NumberFormatException` - if it can't parse

  - ### parseInt

    public static int parseInt(char[] chars, int offset, int len, int radix) throws NumberFormatException
    Parses the string argument as if it was an int value and returns the result. Throws NumberFormatException if the string does not represent an int quantity. The second argument specifies the radix to use when parsing the value.
    Parameters:
      `chars` - a string representation of an int quantity.
      `radix` - the base to use for conversion.
    Returns:
      int the value represented by the argument
    Throws:
      `NumberFormatException` - if the argument could not be parsed as an int quantity.

  - ### oversize

    public static int oversize(int minTargetSize, int bytesPerElement)
    Returns an array size >= minTargetSize, generally over-allocating exponentially to achieve amortized linear-time cost as the array grows.

    NOTE: this was originally borrowed from Python 2.4.2 listobject.c sources (attribution in LICENSE.txt), but has now been substantially changed based on discussions from java-dev thread with subject "Dynamic array reallocation algorithms", started on Jan 12 2010.

    Parameters:
      `minTargetSize` - Minimum required value to be returned.
      `bytesPerElement` - Bytes used by each element of the array. See constants in `RamUsageEstimator`.
    NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

  - ### growExact

    public static <T> T[] growExact(T[] array, int newLength)
    Returns a new array whose size is exact the specified `newLength` without over-allocating

  - ### grow

    public static <T> T[] grow(T[] array)
    Returns a larger array, generally over-allocating exponentially

  - ### grow

    public static <T> T[] grow(T[] array, int minSize)
    Returns an array whose size is at least `minSize`, generally over-allocating exponentially

  - ### growExact

    public static short[] growExact(short[] array, int newLength)
    Returns a new array whose size is exact the specified `newLength` without over-allocating

  - ### grow

    public static short[] grow(short[] array, int minSize)
    Returns an array whose size is at least `minSize`, generally over-allocating exponentially

  - ### grow

    public static short[] grow(short[] array)
    Returns a larger array, generally over-allocating exponentially

  - ### growExact

    public static float[] growExact(float[] array, int newLength)
    Returns a new array whose size is exact the specified `newLength` without over-allocating

  - ### grow

    public static float[] grow(float[] array, int minSize)
    Returns an array whose size is at least `minSize`, generally over-allocating exponentially

  - ### grow

    public static float[] grow(float[] array)
    Returns a larger array, generally over-allocating exponentially

  - ### growExact

    public static double[] growExact(double[] array, int newLength)
    Returns a new array whose size is exact the specified `newLength` without over-allocating

  - ### grow

    public static double[] grow(double[] array, int minSize)
    Returns an array whose size is at least `minSize`, generally over-allocating exponentially

  - ### grow

    public static double[] grow(double[] array)
    Returns a larger array, generally over-allocating exponentially

  - ### growExact

    public static int[] growExact(int[] array, int newLength)
    Returns a new array whose size is exact the specified `newLength` without over-allocating

  - ### growInRange

    public static int[] growInRange(int[] array, int minLength, int maxLength)
    Returns an array whose size is at least `minLength`, generally over-allocating exponentially, but never allocating more than `maxLength` elements.

  - ### growInRange

    public static float[] growInRange(float[] array, int minLength, int maxLength)
    Returns an array whose size is at least `minLength` but not over `maxLength`, growing exponentially if it needs to grow.

  - ### grow

    public static int[] grow(int[] array, int minSize)
    Returns an array whose size is at least `minSize`, generally over-allocating exponentially

  - ### growNoCopy

    public static int[] growNoCopy(int[] array, int minSize)
    Returns an array whose size is at least `minSize`, generally over-allocating exponentially, and it will not copy the origin data to the new array

  - ### grow

    public static int[] grow(int[] array)
    Returns a larger array, generally over-allocating exponentially

  - ### growExact

    public static long[] growExact(long[] array, int newLength)
    Returns a new array whose size is exact the specified `newLength` without over-allocating

  - ### grow

    public static long[] grow(long[] array, int minSize)
    Returns an array whose size is at least `minSize`, generally over-allocating exponentially

  - ### growNoCopy

    public static long[] growNoCopy(long[] array, int minSize)
    Returns an array whose size is at least `minSize`, generally over-allocating exponentially, and it will not copy the origin data to the new array

  - ### grow

    public static long[] grow(long[] array)
    Returns a larger array, generally over-allocating exponentially

  - ### growExact

    public static byte[] growExact(byte[] array, int newLength)
    Returns a new array whose size is exact the specified `newLength` without over-allocating

  - ### grow

    public static byte[] grow(byte[] array, int minSize)
    Returns an array whose size is at least `minSize`, generally over-allocating exponentially

  - ### growNoCopy

    public static byte[] growNoCopy(byte[] array, int minSize)
    Returns an array whose size is at least `minSize`, generally over-allocating exponentially, and it will not copy the origin data to the new array

  - ### grow

    public static byte[] grow(byte[] array)
    Returns a larger array, generally over-allocating exponentially

  - ### growExact

    public static char[] growExact(char[] array, int newLength)
    Returns a new array whose size is exact the specified `newLength` without over-allocating

  - ### grow

    public static char[] grow(char[] array, int minSize)
    Returns an array whose size is at least `minSize`, generally over-allocating exponentially

  - ### grow

    public static char[] grow(char[] array)
    Returns a larger array, generally over-allocating exponentially

  - ### hashCode

    public static int hashCode(char[] array, int start, int end)
    Returns hash of chars in range start (inclusive) to end (inclusive)

  - ### swap

    public static <T> void swap(T[] arr, int i, int j)
    Swap values stored in slots `i` and `j`

  - ### introSort

    public static <T> void introSort(T[] a, int fromIndex, int toIndex, Comparator<? super T> comp)
    Sorts the given array slice using the `Comparator`. This method uses the intro sort algorithm, but falls back to insertion sort for small arrays.
    Parameters:
      `fromIndex` - start index (inclusive)
      `toIndex` - end index (exclusive)
    See Also:
      - `IntroSorter`

  - ### introSort

    public static <T> void introSort(T[] a, Comparator<? super T> comp)
    Sorts the given array using the `Comparator`. This method uses the intro sort algorithm, but falls back to insertion sort for small arrays.
    See Also:
      - `IntroSorter`

  - ### introSort

    public static <T extends Comparable<? super T>> void introSort(T[] a, int fromIndex, int toIndex)
    Sorts the given array slice in natural order. This method uses the intro sort algorithm, but falls back to insertion sort for small arrays.
    Parameters:
      `fromIndex` - start index (inclusive)
      `toIndex` - end index (exclusive)
    See Also:
      - `IntroSorter`

  - ### introSort

    public static <T extends Comparable<? super T>> void introSort(T[] a)
    Sorts the given array in natural order. This method uses the intro sort algorithm, but falls back to insertion sort for small arrays.
    See Also:
      - `IntroSorter`

  - ### timSort

    public static <T> void timSort(T[] a, int fromIndex, int toIndex, Comparator<? super T> comp)
    Sorts the given array slice using the `Comparator`. This method uses the Tim sort algorithm, but falls back to binary sort for small arrays.
    Parameters:
      `fromIndex` - start index (inclusive)
      `toIndex` - end index (exclusive)
    See Also:
      - `TimSorter`

  - ### timSort

    public static <T> void timSort(T[] a, Comparator<? super T> comp)
    Sorts the given array using the `Comparator`. This method uses the Tim sort algorithm, but falls back to binary sort for small arrays.
    See Also:
      - `TimSorter`

  - ### timSort

    public static <T extends Comparable<? super T>> void timSort(T[] a, int fromIndex, int toIndex)
    Sorts the given array slice in natural order. This method uses the Tim sort algorithm, but falls back to binary sort for small arrays.
    Parameters:
      `fromIndex` - start index (inclusive)
      `toIndex` - end index (exclusive)
    See Also:
      - `TimSorter`

  - ### timSort

    public static <T extends Comparable<? super T>> void timSort(T[] a)
    Sorts the given array in natural order. This method uses the Tim sort algorithm, but falls back to binary sort for small arrays.
    See Also:
      - `TimSorter`

  - ### select

    public static <T> void select(T[] arr, int from, int to, int k, Comparator<? super T> comparator)
    Reorganize `arr[from:to[` so that the element at offset k is at the same position as if `arr[from:to]` was sorted, and all elements on its left are less than or equal to it, and all elements on its right are greater than or equal to it.

    This runs in linear time on average and in `n log(n)` time in the worst case.

    Parameters:
      `arr` - Array to be re-organized.
      `from` - Starting index for re-organization. Elements before this index will be left as is.
      `to` - Ending index. Elements after this index will be left as is.
      `k` - Index of element to sort from. Value must be less than 'to' and greater than or equal to 'from'.
      `comparator` - Comparator to use for sorting

  - ### copyArray

    public static byte[] copyArray(byte[] array)
    Copies an array into a new array.

  - ### copyOfSubArray

    public static byte[] copyOfSubArray(byte[] array, int from, int to)
    Copies the specified range of the given array into a new sub array.
    Parameters:
      `array` - the input array
      `from` - the initial index of range to be copied (inclusive)
      `to` - the final index of range to be copied (exclusive)

  - ### copyArray

    public static char[] copyArray(char[] array)
    Copies an array into a new array.

  - ### copyOfSubArray

    public static char[] copyOfSubArray(char[] array, int from, int to)
    Copies the specified range of the given array into a new sub array.
    Parameters:
      `array` - the input array
      `from` - the initial index of range to be copied (inclusive)
      `to` - the final index of range to be copied (exclusive)

  - ### copyArray

    public static short[] copyArray(short[] array)
    Copies an array into a new array.

  - ### copyOfSubArray

    public static short[] copyOfSubArray(short[] array, int from, int to)
    Copies the specified range of the given array into a new sub array.
    Parameters:
      `array` - the input array
      `from` - the initial index of range to be copied (inclusive)
      `to` - the final index of range to be copied (exclusive)

  - ### copyArray

    public static int[] copyArray(int[] array)
    Copies an array into a new array.

  - ### copyOfSubArray

    public static int[] copyOfSubArray(int[] array, int from, int to)
    Copies the specified range of the given array into a new sub array.
    Parameters:
      `array` - the input array
      `from` - the initial index of range to be copied (inclusive)
      `to` - the final index of range to be copied (exclusive)

  - ### copyArray

    public static long[] copyArray(long[] array)
    Copies an array into a new array.

  - ### copyOfSubArray

    public static long[] copyOfSubArray(long[] array, int from, int to)
    Copies the specified range of the given array into a new sub array.
    Parameters:
      `array` - the input array
      `from` - the initial index of range to be copied (inclusive)
      `to` - the final index of range to be copied (exclusive)

  - ### copyArray

    public static float[] copyArray(float[] array)
    Copies an array into a new array.

  - ### copyOfSubArray

    public static float[] copyOfSubArray(float[] array, int from, int to)
    Copies the specified range of the given array into a new sub array.
    Parameters:
      `array` - the input array
      `from` - the initial index of range to be copied (inclusive)
      `to` - the final index of range to be copied (exclusive)

  - ### copyArray

    public static double[] copyArray(double[] array)
    Copies an array into a new array.

  - ### copyOfSubArray

    public static double[] copyOfSubArray(double[] array, int from, int to)
    Copies the specified range of the given array into a new sub array.
    Parameters:
      `array` - the input array
      `from` - the initial index of range to be copied (inclusive)
      `to` - the final index of range to be copied (exclusive)

  - ### copyArray

    public static <T> T[] copyArray(T[] array)
    Copies an array into a new array.

  - ### copyOfSubArray

    public static <T> T[] copyOfSubArray(T[] array, int from, int to)
    Copies the specified range of the given array into a new sub array.
    Parameters:
      `array` - the input array
      `from` - the initial index of range to be copied (inclusive)
      `to` - the final index of range to be copied (exclusive)

  - ### getUnsignedComparator

    public static ArrayUtil.ByteArrayComparator getUnsignedComparator(int numBytes)
    Return a comparator for exactly the specified number of bytes.

  - ### compareUnsigned8

    public static int compareUnsigned8(byte[] a, int aOffset, byte[] b, int bOffset)
    Compare exactly 8 unsigned bytes from the provided arrays.

  - ### compareUnsigned4

    public static int compareUnsigned4(byte[] a, int aOffset, byte[] b, int bOffset)
    Compare exactly 4 unsigned bytes from the provided arrays.