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.

Field Summary

Fields

Modifier and Type	Field	Description
static int	MAX_ARRAY_LENGTH	Maximum length for an array; we set this to "a bit" below Integer.MAX_VALUE because the exact max allowed byte[] is JVM dependent, so we want to avoid a case where a large value worked during indexing on one JVM but failed later at search time with a different JVM.

Method Summary

Modifier and Type	Method	Description
static boolean	equals(byte[] left, int offsetLeft, byte[] right, int offsetRight, int length)	See if two array slices are the same.
static boolean	equals(char[] left, int offsetLeft, char[] right, int offsetRight, int length)	See if two array slices are the same.
static boolean	equals(int[] left, int offsetLeft, int[] right, int offsetRight, int length)	See if two array slices are the same.
static int	getShrinkSize(int currentSize, int targetSize, int bytesPerElement)
static boolean[]	grow(boolean[] array)
static boolean[]	grow(boolean[] array, int minSize)
static byte[]	grow(byte[] array)
static byte[]	grow(byte[] array, int minSize)
static char[]	grow(char[] array)
static char[]	grow(char[] array, int minSize)
static double[]	grow(double[] array)
static double[]	grow(double[] array, int minSize)
static float[]	grow(float[] array)
static float[][]	grow(float[][] array)
static float[][]	grow(float[][] array, int minSize)
static float[]	grow(float[] array, int minSize)
static int[]	grow(int[] array)
static int[][]	grow(int[][] array)
static int[][]	grow(int[][] array, int minSize)
static int[]	grow(int[] array, int minSize)
static long[]	grow(long[] array)
static long[]	grow(long[] array, int minSize)
static short[]	grow(short[] array)
static short[]	grow(short[] array, int minSize)
static int	hashCode(byte[] array, int start, int end)	Returns hash of bytes in range start (inclusive) to end (inclusive)
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 <T extends Comparable<? super T>> Comparator<T>	naturalComparator()	Get the natural Comparator for the provided object class.
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)	Parses the string argument as if it was an int value and returns the result.
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 boolean[]	shrink(boolean[] array, int targetSize)
static byte[]	shrink(byte[] array, int targetSize)
static char[]	shrink(char[] array, int targetSize)
static float[][]	shrink(float[][] array, int targetSize)
static int[][]	shrink(int[][] array, int targetSize)
static int[]	shrink(int[] array, int targetSize)
static long[]	shrink(long[] array, int targetSize)
static short[]	shrink(short[] array, int targetSize)
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.
static int[]	toIntArray(Collection<Integer> ints)

Methods inherited from class java.lang.Object

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

Field Detail

MAX_ARRAY_LENGTH

public static final int MAX_ARRAY_LENGTH

Maximum length for an array; we set this to "a bit" below Integer.MAX_VALUE because the exact max allowed byte[] is JVM dependent, so we want to avoid a case where a large value worked during indexing on one JVM but failed later at search time with a different JVM.

See Also:

Constant Field Values

Method Detail

parseInt

public static int parseInt(char[] chars)
                    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.

Parameters:

chars - a string representation of an int quantity.

Returns:

int the value represented by the argument

Throws:

NumberFormatException - if the argument could not be parsed as an int quantity.

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.

getShrinkSize

public static int getShrinkSize(int currentSize,
                                int targetSize,
                                int bytesPerElement)

grow

public static short[] grow(short[] array,
                           int minSize)

grow

public static short[] grow(short[] array)

grow

public static float[] grow(float[] array,
                           int minSize)

grow

public static float[] grow(float[] array)

grow

public static double[] grow(double[] array,
                            int minSize)

grow

public static double[] grow(double[] array)

shrink

public static short[] shrink(short[] array,
                             int targetSize)

grow

public static int[] grow(int[] array,
                         int minSize)

grow

public static int[] grow(int[] array)

shrink

public static int[] shrink(int[] array,
                           int targetSize)

grow

public static long[] grow(long[] array,
                          int minSize)

grow

public static long[] grow(long[] array)

shrink

public static long[] shrink(long[] array,
                            int targetSize)

grow

public static byte[] grow(byte[] array,
                          int minSize)

grow

public static byte[] grow(byte[] array)

shrink

public static byte[] shrink(byte[] array,
                            int targetSize)

grow

public static boolean[] grow(boolean[] array,
                             int minSize)

grow

public static boolean[] grow(boolean[] array)

shrink

public static boolean[] shrink(boolean[] array,
                               int targetSize)

grow

public static char[] grow(char[] array,
                          int minSize)

grow

public static char[] grow(char[] array)

shrink

public static char[] shrink(char[] array,
                            int targetSize)

grow

public static int[][] grow(int[][] array,
                           int minSize)

grow

public static int[][] grow(int[][] array)

shrink

public static int[][] shrink(int[][] array,
                             int targetSize)

grow

public static float[][] grow(float[][] array,
                             int minSize)

grow

public static float[][] grow(float[][] array)

shrink

public static float[][] shrink(float[][] array,
                               int targetSize)

hashCode

public static int hashCode(char[] array,
                           int start,
                           int end)

Returns hash of chars in range start (inclusive) to end (inclusive)

hashCode

public static int hashCode(byte[] array,
                           int start,
                           int end)

Returns hash of bytes in range start (inclusive) to end (inclusive)

equals

public static boolean equals(char[] left,
                             int offsetLeft,
                             char[] right,
                             int offsetRight,
                             int length)

See if two array slices are the same.

Parameters:

left - The left array to compare

offsetLeft - The offset into the array. Must be positive

right - The right array to compare

offsetRight - the offset into the right array. Must be positive

length - The length of the section of the array to compare

Returns:

true if the two arrays, starting at their respective offsets, are equal

See Also:

Arrays.equals(char[], char[])

equals

public static boolean equals(byte[] left,
                             int offsetLeft,
                             byte[] right,
                             int offsetRight,
                             int length)

See if two array slices are the same.

Parameters:

left - The left array to compare

offsetLeft - The offset into the array. Must be positive

right - The right array to compare

offsetRight - the offset into the right array. Must be positive

length - The length of the section of the array to compare

Returns:

true if the two arrays, starting at their respective offsets, are equal

See Also:

Arrays.equals(byte[], byte[])

equals

public static boolean equals(int[] left,
                             int offsetLeft,
                             int[] right,
                             int offsetRight,
                             int length)

See if two array slices are the same.

Parameters:

left - The left array to compare

offsetLeft - The offset into the array. Must be positive

right - The right array to compare

offsetRight - the offset into the right array. Must be positive

length - The length of the section of the array to compare

Returns:

true if the two arrays, starting at their respective offsets, are equal

See Also:

Arrays.equals(char[], char[])

toIntArray

public static int[] toIntArray(Collection<Integer> ints)

naturalComparator

public static <T extends Comparable<? super T>> Comparator<T> naturalComparator()

Get the natural Comparator for the provided object class.

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)

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.

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)

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.

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)

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.

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)

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.