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[]
    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 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

    • grow

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

    • 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

    • 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

    • 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:

    • 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:

    • 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:

    • 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:

    • 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:

    • 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:

    • 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:

    • 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:

    • 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

    • 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)

    • 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)

    • 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)

    • 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)

    • 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)

    • 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)

    • 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)

    • 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.