JavaTM 2 Platform
Std. Ed. v1.4.2

java.util
Class Arrays

java.lang.Object
  extended byjava.util.Arrays

public class Arrays
extends Object

This class contains various methods for manipulating arrays (such as sorting and searching). This class also contains a static factory that allows arrays to be viewed as lists.

The methods in this class all throw a NullPointerException if the specified array reference is null.

The documentation for the methods contained in this class includes briefs description of the implementations. Such descriptions should be regarded as implementation notes, rather than parts of the specification. Implementors should feel free to substitute other algorithms, so long as the specification itself is adhered to. (For example, the algorithm used by sort(Object[]) does not have to be a mergesort, but it does have to be stable.)

This class is a member of the Java Collections Framework.

Since:
1.2
See Also:
Comparable, Comparator

Method Summary
static List asList(Object[] a)
          Returns a fixed-size list backed by the specified array.
static int binarySearch(byte[] a, byte key)
          Searches the specified array of bytes for the specified value using the binary search algorithm.
static int binarySearch(char[] a, char key)
          Searches the specified array of chars for the specified value using the binary search algorithm.
static int binarySearch(double[] a, double key)
          Searches the specified array of doubles for the specified value using the binary search algorithm.
static int binarySearch(float[] a, float key)
          Searches the specified array of floats for the specified value using the binary search algorithm.
static int binarySearch(int[] a, int key)
          Searches the specified array of ints for the specified value using the binary search algorithm.
static int binarySearch(long[] a, long key)
          Searches the specified array of longs for the specified value using the binary search algorithm.
static int binarySearch(Object[] a, Object key)
          Searches the specified array for the specified object using the binary search algorithm.
static int binarySearch(Object[] a, Object key, Comparator c)
          Searches the specified array for the specified object using the binary search algorithm.
static int binarySearch(short[] a, short key)
          Searches the specified array of shorts for the specified value using the binary search algorithm.
static boolean equals(boolean[] a, boolean[] a2)
          Returns true if the two specified arrays of booleans are equal to one another.
static boolean equals(byte[] a, byte[] a2)
          Returns true if the two specified arrays of bytes are equal to one another.
static boolean equals(char[] a, char[] a2)
          Returns true if the two specified arrays of chars are equal to one another.
static boolean equals(double[] a, double[] a2)
          Returns true if the two specified arrays of doubles are equal to one another.
static boolean equals(float[] a, float[] a2)
          Returns true if the two specified arrays of floats are equal to one another.
static boolean equals(int[] a, int[] a2)
          Returns true if the two specified arrays of ints are equal to one another.
static boolean equals(long[] a, long[] a2)
          Returns true if the two specified arrays of longs are equal to one another.
static boolean equals(Object[] a, Object[] a2)
          Returns true if the two specified arrays of Objects are equal to one another.
static boolean equals(short[] a, short[] a2)
          Returns true if the two specified arrays of shorts are equal to one another.
static void fill(boolean[] a, boolean val)
          Assigns the specified boolean value to each element of the specified array of booleans.
static void fill(boolean[] a, int fromIndex, int toIndex, boolean val)
          Assigns the specified boolean value to each element of the specified range of the specified array of booleans.
static void fill(byte[] a, byte val)
          Assigns the specified byte value to each element of the specified array of bytes.
static void fill(byte[] a, int fromIndex, int toIndex, byte val)
          Assigns the specified byte value to each element of the specified range of the specified array of bytes.
static void fill(char[] a, char val)
          Assigns the specified char value to each element of the specified array of chars.
static void fill(char[] a, int fromIndex, int toIndex, char val)
          Assigns the specified char value to each element of the specified range of the specified array of chars.
static void fill(double[] a, double val)
          Assigns the specified double value to each element of the specified array of doubles.
static void fill(double[] a, int fromIndex, int toIndex, double val)
          Assigns the specified double value to each element of the specified range of the specified array of doubles.
static void fill(float[] a, float val)
          Assigns the specified float value to each element of the specified array of floats.
static void fill(float[] a, int fromIndex, int toIndex, float val)
          Assigns the specified float value to each element of the specified range of the specified array of floats.
static void fill(int[] a, int val)
          Assigns the specified int value to each element of the specified array of ints.
static void fill(int[] a, int fromIndex, int toIndex, int val)
          Assigns the specified int value to each element of the specified range of the specified array of ints.
static void fill(long[] a, int fromIndex, int toIndex, long val)
          Assigns the specified long value to each element of the specified range of the specified array of longs.
static void fill(long[] a, long val)
          Assigns the specified long value to each element of the specified array of longs.
static void fill(Object[] a, int fromIndex, int toIndex, Object val)
          Assigns the specified Object reference to each element of the specified range of the specified array of Objects.
static void fill(Object[] a, Object val)
          Assigns the specified Object reference to each element of the specified array of Objects.
static void fill(short[] a, int fromIndex, int toIndex, short val)
          Assigns the specified short value to each element of the specified range of the specified array of shorts.
static void fill(short[] a, short val)
          Assigns the specified short value to each element of the specified array of shorts.
static void sort(byte[] a)
          Sorts the specified array of bytes into ascending numerical order.
static void sort(byte[] a, int fromIndex, int toIndex)
          Sorts the specified range of the specified array of bytes into ascending numerical order.
static void sort(char[] a)
          Sorts the specified array of chars into ascending numerical order.
static void sort(char[] a, int fromIndex, int toIndex)
          Sorts the specified range of the specified array of chars into ascending numerical order.
static void sort(double[] a)
          Sorts the specified array of doubles into ascending numerical order.
static void sort(double[] a, int fromIndex, int toIndex)
          Sorts the specified range of the specified array of doubles into ascending numerical order.
static void sort(float[] a)
          Sorts the specified array of floats into ascending numerical order.
static void sort(float[] a, int fromIndex, int toIndex)
          Sorts the specified range of the specified array of floats into ascending numerical order.
static void sort(int[] a)
          Sorts the specified array of ints into ascending numerical order.
static void sort(int[] a, int fromIndex, int toIndex)
          Sorts the specified range of the specified array of ints into ascending numerical order.
static void sort(long[] a)
          Sorts the specified array of longs into ascending numerical order.
static void sort(long[] a, int fromIndex, int toIndex)
          Sorts the specified range of the specified array of longs into ascending numerical order.
static void sort(Object[] a)
          Sorts the specified array of objects into ascending order, according to the natural ordering of its elements.
static void sort(Object[] a, Comparator c)
          Sorts the specified array of objects according to the order induced by the specified comparator.
static void sort(Object[] a, int fromIndex, int toIndex)
          Sorts the specified range of the specified array of objects into ascending order, according to the natural ordering of its elements.
static void sort(Object[] a, int fromIndex, int toIndex, Comparator c)
          Sorts the specified range of the specified array of objects according to the order induced by the specified comparator.
static void sort(short[] a)
          Sorts the specified array of shorts into ascending numerical order.
static void sort(short[] a, int fromIndex, int toIndex)
          Sorts the specified range of the specified array of shorts into ascending numerical order.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

sort

public static void sort(long[] a)
Sorts the specified array of longs into ascending numerical order. The sorting algorithm is a tuned quicksort, adapted from Jon L. Bentley and M. Douglas McIlroy's "Engineering a Sort Function", Software-Practice and Experience, Vol. 23(11) P. 1249-1265 (November 1993). This algorithm offers n*log(n) performance on many data sets that cause other quicksorts to degrade to quadratic performance.

Parameters:
a - the array to be sorted.

sort

public static void sort(long[] a,
                        int fromIndex,
                        int toIndex)
Sorts the specified range of the specified array of longs into ascending numerical order. The range to be sorted extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be sorted is empty.)

The sorting algorithm is a tuned quicksort, adapted from Jon L. Bentley and M. Douglas McIlroy's "Engineering a Sort Function", Software-Practice and Experience, Vol. 23(11) P. 1249-1265 (November 1993). This algorithm offers n*log(n) performance on many data sets that cause other quicksorts to degrade to quadratic performance.

Parameters:
a - the array to be sorted.
fromIndex - the index of the first element (inclusive) to be sorted.
toIndex - the index of the last element (exclusive) to be sorted.
Throws:
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length

sort

public static void sort(int[] a)
Sorts the specified array of ints into ascending numerical order. The sorting algorithm is a tuned quicksort, adapted from Jon L. Bentley and M. Douglas McIlroy's "Engineering a Sort Function", Software-Practice and Experience, Vol. 23(11) P. 1249-1265 (November 1993). This algorithm offers n*log(n) performance on many data sets that cause other quicksorts to degrade to quadratic performance.

Parameters:
a - the array to be sorted.

sort

public static void sort(int[] a,
                        int fromIndex,
                        int toIndex)
Sorts the specified range of the specified array of ints into ascending numerical order. The range to be sorted extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be sorted is empty.)

The sorting algorithm is a tuned quicksort, adapted from Jon L. Bentley and M. Douglas McIlroy's "Engineering a Sort Function", Software-Practice and Experience, Vol. 23(11) P. 1249-1265 (November 1993). This algorithm offers n*log(n) performance on many data sets that cause other quicksorts to degrade to quadratic performance.

Parameters:
a - the array to be sorted.
fromIndex - the index of the first element (inclusive) to be sorted.
toIndex - the index of the last element (exclusive) to be sorted.
Throws:
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length

sort

public static void sort(short[] a)
Sorts the specified array of shorts into ascending numerical order. The sorting algorithm is a tuned quicksort, adapted from Jon L. Bentley and M. Douglas McIlroy's "Engineering a Sort Function", Software-Practice and Experience, Vol. 23(11) P. 1249-1265 (November 1993). This algorithm offers n*log(n) performance on many data sets that cause other quicksorts to degrade to quadratic performance.

Parameters:
a - the array to be sorted.

sort

public static void sort(short[] a,
                        int fromIndex,
                        int toIndex)
Sorts the specified range of the specified array of shorts into ascending numerical order. The range to be sorted extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be sorted is empty.)

The sorting algorithm is a tuned quicksort, adapted from Jon L. Bentley and M. Douglas McIlroy's "Engineering a Sort Function", Software-Practice and Experience, Vol. 23(11) P. 1249-1265 (November 1993). This algorithm offers n*log(n) performance on many data sets that cause other quicksorts to degrade to quadratic performance.

Parameters:
a - the array to be sorted.
fromIndex - the index of the first element (inclusive) to be sorted.
toIndex - the index of the last element (exclusive) to be sorted.
Throws:
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length

sort

public static void sort(char[] a)
Sorts the specified array of chars into ascending numerical order. The sorting algorithm is a tuned quicksort, adapted from Jon L. Bentley and M. Douglas McIlroy's "Engineering a Sort Function", Software-Practice and Experience, Vol. 23(11) P. 1249-1265 (November 1993). This algorithm offers n*log(n) performance on many data sets that cause other quicksorts to degrade to quadratic performance.

Parameters:
a - the array to be sorted.

sort

public static void sort(char[] a,
                        int fromIndex,
                        int toIndex)
Sorts the specified range of the specified array of chars into ascending numerical order. The range to be sorted extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be sorted is empty.)

The sorting algorithm is a tuned quicksort, adapted from Jon L. Bentley and M. Douglas McIlroy's "Engineering a Sort Function", Software-Practice and Experience, Vol. 23(11) P. 1249-1265 (November 1993). This algorithm offers n*log(n) performance on many data sets that cause other quicksorts to degrade to quadratic performance.

Parameters:
a - the array to be sorted.
fromIndex - the index of the first element (inclusive) to be sorted.
toIndex - the index of the last element (exclusive) to be sorted.
Throws:
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length

sort

public static void sort(byte[] a)
Sorts the specified array of bytes into ascending numerical order. The sorting algorithm is a tuned quicksort, adapted from Jon L. Bentley and M. Douglas McIlroy's "Engineering a Sort Function", Software-Practice and Experience, Vol. 23(11) P. 1249-1265 (November 1993). This algorithm offers n*log(n) performance on many data sets that cause other quicksorts to degrade to quadratic performance.

Parameters:
a - the array to be sorted.

sort

public static void sort(byte[] a,
                        int fromIndex,
                        int toIndex)
Sorts the specified range of the specified array of bytes into ascending numerical order. The range to be sorted extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be sorted is empty.)

The sorting algorithm is a tuned quicksort, adapted from Jon L. Bentley and M. Douglas McIlroy's "Engineering a Sort Function", Software-Practice and Experience, Vol. 23(11) P. 1249-1265 (November 1993). This algorithm offers n*log(n) performance on many data sets that cause other quicksorts to degrade to quadratic performance.

Parameters:
a - the array to be sorted.
fromIndex - the index of the first element (inclusive) to be sorted.
toIndex - the index of the last element (exclusive) to be sorted.
Throws:
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length

sort

public static void sort(double[] a)
Sorts the specified array of doubles into ascending numerical order.

The < relation does not provide a total order on all floating-point values; although they are distinct numbers -0.0 == 0.0 is true and a NaN value compares neither less than, greater than, nor equal to any floating-point value, even itself. To allow the sort to proceed, instead of using the < relation to determine ascending numerical order, this method uses the total order imposed by Double.compareTo(java.lang.Double). This ordering differs from the < relation in that -0.0 is treated as less than 0.0 and NaN is considered greater than any other floating-point value. For the purposes of sorting, all NaN values are considered equivalent and equal.

The sorting algorithm is a tuned quicksort, adapted from Jon L. Bentley and M. Douglas McIlroy's "Engineering a Sort Function", Software-Practice and Experience, Vol. 23(11) P. 1249-1265 (November 1993). This algorithm offers n*log(n) performance on many data sets that cause other quicksorts to degrade to quadratic performance.

Parameters:
a - the array to be sorted.

sort

public static void sort(double[] a,
                        int fromIndex,
                        int toIndex)
Sorts the specified range of the specified array of doubles into ascending numerical order. The range to be sorted extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be sorted is empty.)

The < relation does not provide a total order on all floating-point values; although they are distinct numbers -0.0 == 0.0 is true and a NaN value compares neither less than, greater than, nor equal to any floating-point value, even itself. To allow the sort to proceed, instead of using the < relation to determine ascending numerical order, this method uses the total order imposed by Double.compareTo(java.lang.Double). This ordering differs from the < relation in that -0.0 is treated as less than 0.0 and NaN is considered greater than any other floating-point value. For the purposes of sorting, all NaN values are considered equivalent and equal.

The sorting algorithm is a tuned quicksort, adapted from Jon L. Bentley and M. Douglas McIlroy's "Engineering a Sort Function", Software-Practice and Experience, Vol. 23(11) P. 1249-1265 (November 1993). This algorithm offers n*log(n) performance on many data sets that cause other quicksorts to degrade to quadratic performance.

Parameters:
a - the array to be sorted.
fromIndex - the index of the first element (inclusive) to be sorted.
toIndex - the index of the last element (exclusive) to be sorted.
Throws:
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length

sort

public static void sort(float[] a)
Sorts the specified array of floats into ascending numerical order.

The < relation does not provide a total order on all floating-point values; although they are distinct numbers -0.0f == 0.0f is true and a NaN value compares neither less than, greater than, nor equal to any floating-point value, even itself. To allow the sort to proceed, instead of using the < relation to determine ascending numerical order, this method uses the total order imposed by Float.compareTo(java.lang.Float). This ordering differs from the < relation in that -0.0f is treated as less than 0.0f and NaN is considered greater than any other floating-point value. For the purposes of sorting, all NaN values are considered equivalent and equal.

The sorting algorithm is a tuned quicksort, adapted from Jon L. Bentley and M. Douglas McIlroy's "Engineering a Sort Function", Software-Practice and Experience, Vol. 23(11) P. 1249-1265 (November 1993). This algorithm offers n*log(n) performance on many data sets that cause other quicksorts to degrade to quadratic performance.

Parameters:
a - the array to be sorted.

sort

public static void sort(float[] a,
                        int fromIndex,
                        int toIndex)
Sorts the specified range of the specified array of floats into ascending numerical order. The range to be sorted extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be sorted is empty.)

The < relation does not provide a total order on all floating-point values; although they are distinct numbers -0.0f == 0.0f is true and a NaN value compares neither less than, greater than, nor equal to any floating-point value, even itself. To allow the sort to proceed, instead of using the < relation to determine ascending numerical order, this method uses the total order imposed by Float.compareTo(java.lang.Float). This ordering differs from the < relation in that -0.0f is treated as less than 0.0f and NaN is considered greater than any other floating-point value. For the purposes of sorting, all NaN values are considered equivalent and equal.

The sorting algorithm is a tuned quicksort, adapted from Jon L. Bentley and M. Douglas McIlroy's "Engineering a Sort Function", Software-Practice and Experience, Vol. 23(11) P. 1249-1265 (November 1993). This algorithm offers n*log(n) performance on many data sets that cause other quicksorts to degrade to quadratic performance.

Parameters:
a - the array to be sorted.
fromIndex - the index of the first element (inclusive) to be sorted.
toIndex - the index of the last element (exclusive) to be sorted.
Throws:
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length

sort

public static void sort(Object[] a)
Sorts the specified array of objects into ascending order, according to the natural ordering of its elements. All elements in the array must implement the Comparable interface. Furthermore, all elements in the array must be mutually comparable (that is, e1.compareTo(e2) must not throw a ClassCastException for any elements e1 and e2 in the array).

This sort is guaranteed to be stable: equal elements will not be reordered as a result of the sort.

The sorting algorithm is a modified mergesort (in which the merge is omitted if the highest element in the low sublist is less than the lowest element in the high sublist). This algorithm offers guaranteed n*log(n) performance.

Parameters:
a - the array to be sorted.
Throws:
ClassCastException - if the array contains elements that are not mutually comparable (for example, strings and integers).
See Also:
Comparable

sort

public static void sort(Object[] a,
                        int fromIndex,
                        int toIndex)
Sorts the specified range of the specified array of objects into ascending order, according to the natural ordering of its elements. The range to be sorted extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be sorted is empty.) All elements in this range must implement the Comparable interface. Furthermore, all elements in this range must be mutually comparable (that is, e1.compareTo(e2) must not throw a ClassCastException for any elements e1 and e2 in the array).

This sort is guaranteed to be stable: equal elements will not be reordered as a result of the sort.

The sorting algorithm is a modified mergesort (in which the merge is omitted if the highest element in the low sublist is less than the lowest element in the high sublist). This algorithm offers guaranteed n*log(n) performance.

Parameters:
a - the array to be sorted.
fromIndex - the index of the first element (inclusive) to be sorted.
toIndex - the index of the last element (exclusive) to be sorted.
Throws:
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length
ClassCastException - if the array contains elements that are not mutually comparable (for example, strings and integers).
See Also:
Comparable

sort

public static void sort(Object[] a,
                        Comparator c)
Sorts the specified array of objects according to the order induced by the specified comparator. All elements in the array must be mutually comparable by the specified comparator (that is, c.compare(e1, e2) must not throw a ClassCastException for any elements e1 and e2 in the array).

This sort is guaranteed to be stable: equal elements will not be reordered as a result of the sort.

The sorting algorithm is a modified mergesort (in which the merge is omitted if the highest element in the low sublist is less than the lowest element in the high sublist). This algorithm offers guaranteed n*log(n) performance.

Parameters:
a - the array to be sorted.
c - the comparator to determine the order of the array. A null value indicates that the elements' natural ordering should be used.
Throws:
ClassCastException - if the array contains elements that are not mutually comparable using the specified comparator.
See Also:
Comparator

sort

public static void sort(Object[] a,
                        int fromIndex,
                        int toIndex,
                        Comparator c)
Sorts the specified range of the specified array of objects according to the order induced by the specified comparator. The range to be sorted extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be sorted is empty.) All elements in the range must be mutually comparable by the specified comparator (that is, c.compare(e1, e2) must not throw a ClassCastException for any elements e1 and e2 in the range).

This sort is guaranteed to be stable: equal elements will not be reordered as a result of the sort.

The sorting algorithm is a modified mergesort (in which the merge is omitted if the highest element in the low sublist is less than the lowest element in the high sublist). This algorithm offers guaranteed n*log(n) performance.

Parameters:
a - the array to be sorted.
fromIndex - the index of the first element (inclusive) to be sorted.
toIndex - the index of the last element (exclusive) to be sorted.
c - the comparator to determine the order of the array. A null value indicates that the elements' natural ordering should be used.
Throws:
ClassCastException - if the array contains elements that are not mutually comparable using the specified comparator.
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length
See Also:
Comparator

binarySearch

public static int binarySearch(long[] a,
                               long key)
Searches the specified array of longs for the specified value using the binary search algorithm. The array must be sorted (as by the sort method, above) prior to making this call. If it is not sorted, the results are undefined. If the array contains multiple elements with the specified value, there is no guarantee which one will be found.

Parameters:
a - the array to be searched.
key - the value to be searched for.
Returns:
index of the search key, if it is contained in the list; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the list: the index of the first element greater than the key, or list.size(), if all elements in the list are less than the specified key. Note that this guarantees that the return value will be >= 0 if and only if the key is found.
See Also:
sort(long[])

binarySearch

public static int binarySearch(int[] a,
                               int key)
Searches the specified array of ints for the specified value using the binary search algorithm. The array must be sorted (as by the sort method, above) prior to making this call. If it is not sorted, the results are undefined. If the array contains multiple elements with the specified value, there is no guarantee which one will be found.

Parameters:
a - the array to be searched.
key - the value to be searched for.
Returns:
index of the search key, if it is contained in the list; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the list: the index of the first element greater than the key, or list.size(), if all elements in the list are less than the specified key. Note that this guarantees that the return value will be >= 0 if and only if the key is found.
See Also:
sort(int[])

binarySearch

public static int binarySearch(short[] a,
                               short key)
Searches the specified array of shorts for the specified value using the binary search algorithm. The array must be sorted (as by the sort method, above) prior to making this call. If it is not sorted, the results are undefined. If the array contains multiple elements with the specified value, there is no guarantee which one will be found.

Parameters:
a - the array to be searched.
key - the value to be searched for.
Returns:
index of the search key, if it is contained in the list; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the list: the index of the first element greater than the key, or list.size(), if all elements in the list are less than the specified key. Note that this guarantees that the return value will be >= 0 if and only if the key is found.
See Also:
sort(short[])

binarySearch

public static int binarySearch(char[] a,
                               char key)
Searches the specified array of chars for the specified value using the binary search algorithm. The array must be sorted (as by the sort method, above) prior to making this call. If it is not sorted, the results are undefined. If the array contains multiple elements with the specified value, there is no guarantee which one will be found.

Parameters:
a - the array to be searched.
key - the value to be searched for.
Returns:
index of the search key, if it is contained in the list; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the list: the index of the first element greater than the key, or list.size(), if all elements in the list are less than the specified key. Note that this guarantees that the return value will be >= 0 if and only if the key is found.
See Also:
sort(char[])

binarySearch

public static int binarySearch(byte[] a,
                               byte key)
Searches the specified array of bytes for the specified value using the binary search algorithm. The array must be sorted (as by the sort method, above) prior to making this call. If it is not sorted, the results are undefined. If the array contains multiple elements with the specified value, there is no guarantee which one will be found.

Parameters:
a - the array to be searched.
key - the value to be searched for.
Returns:
index of the search key, if it is contained in the list; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the list: the index of the first element greater than the key, or list.size(), if all elements in the list are less than the specified key. Note that this guarantees that the return value will be >= 0 if and only if the key is found.
See Also:
sort(byte[])

binarySearch

public static int binarySearch(double[] a,
                               double key)
Searches the specified array of doubles for the specified value using the binary search algorithm. The array must be sorted (as by the sort method, above) prior to making this call. If it is not sorted, the results are undefined. If the array contains multiple elements with the specified value, there is no guarantee which one will be found. This method considers all NaN values to be equivalent and equal.

Parameters:
a - the array to be searched.
key - the value to be searched for.
Returns:
index of the search key, if it is contained in the list; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the list: the index of the first element greater than the key, or list.size(), if all elements in the list are less than the specified key. Note that this guarantees that the return value will be >= 0 if and only if the key is found.
See Also:
sort(double[])

binarySearch

public static int binarySearch(float[] a,
                               float key)
Searches the specified array of floats for the specified value using the binary search algorithm. The array must be sorted (as by the sort method, above) prior to making this call. If it is not sorted, the results are undefined. If the array contains multiple elements with the specified value, there is no guarantee which one will be found. This method considers all NaN values to be equivalent and equal.

Parameters:
a - the array to be searched.
key - the value to be searched for.
Returns:
index of the search key, if it is contained in the list; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the list: the index of the first element greater than the key, or list.size(), if all elements in the list are less than the specified key. Note that this guarantees that the return value will be >= 0 if and only if the key is found.
See Also:
sort(float[])

binarySearch

public static int binarySearch(Object[] a,
                               Object key)
Searches the specified array for the specified object using the binary search algorithm. The array must be sorted into ascending order according to the natural ordering of its elements (as by Sort(Object[]), above) prior to making this call. If it is not sorted, the results are undefined. (If the array contains elements that are not mutually comparable (for example,strings and integers), it cannot be sorted according to the natural order of its elements, hence results are undefined.) If the array contains multiple elements equal to the specified object, there is no guarantee which one will be found.

Parameters:
a - the array to be searched.
key - the value to be searched for.
Returns:
index of the search key, if it is contained in the list; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the list: the index of the first element greater than the key, or list.size(), if all elements in the list are less than the specified key. Note that this guarantees that the return value will be >= 0 if and only if the key is found.
Throws:
ClassCastException - if the search key in not comparable to the elements of the array.
See Also:
Comparable, sort(Object[])

binarySearch

public static int binarySearch(Object[] a,
                               Object key,
                               Comparator c)
Searches the specified array for the specified object using the binary search algorithm. The array must be sorted into ascending order according to the specified comparator (as by the Sort(Object[], Comparator) method, above), prior to making this call. If it is not sorted, the results are undefined. If the array contains multiple elements equal to the specified object, there is no guarantee which one will be found.

Parameters:
a - the array to be searched.
key - the value to be searched for.
c - the comparator by which the array is ordered. A null value indicates that the elements' natural ordering should be used.
Returns:
index of the search key, if it is contained in the list; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the list: the index of the first element greater than the key, or list.size(), if all elements in the list are less than the specified key. Note that this guarantees that the return value will be >= 0 if and only if the key is found.
Throws:
ClassCastException - if the array contains elements that are not mutually comparable using the specified comparator, or the search key in not mutually comparable with the elements of the array using this comparator.
See Also:
Comparable, sort(Object[], Comparator)

equals

public static boolean equals(long[] a,
                             long[] a2)
Returns true if the two specified arrays of longs are equal to one another. Two arrays are considered equal if both arrays contain the same number of elements, and all corresponding pairs of elements in the two arrays are equal. In other words, two arrays are equal if they contain the same elements in the same order. Also, two array references are considered equal if both are null.

Parameters:
a - one array to be tested for equality.
a2 - the other array to be tested for equality.
Returns:
true if the two arrays are equal.

equals

public static boolean equals(int[] a,
                             int[] a2)
Returns true if the two specified arrays of ints are equal to one another. Two arrays are considered equal if both arrays contain the same number of elements, and all corresponding pairs of elements in the two arrays are equal. In other words, two arrays are equal if they contain the same elements in the same order. Also, two array references are considered equal if both are null.

Parameters:
a - one array to be tested for equality.
a2 - the other array to be tested for equality.
Returns:
true if the two arrays are equal.

equals

public static boolean equals(short[] a,
                             short[] a2)
Returns true if the two specified arrays of shorts are equal to one another. Two arrays are considered equal if both arrays contain the same number of elements, and all corresponding pairs of elements in the two arrays are equal. In other words, two arrays are equal if they contain the same elements in the same order. Also, two array references are considered equal if both are null.

Parameters:
a - one array to be tested for equality.
a2 - the other array to be tested for equality.
Returns:
true if the two arrays are equal.

equals

public static boolean equals(char[] a,
                             char[] a2)
Returns true if the two specified arrays of chars are equal to one another. Two arrays are considered equal if both arrays contain the same number of elements, and all corresponding pairs of elements in the two arrays are equal. In other words, two arrays are equal if they contain the same elements in the same order. Also, two array references are considered equal if both are null.

Parameters:
a - one array to be tested for equality.
a2 - the other array to be tested for equality.
Returns:
true if the two arrays are equal.

equals

public static boolean equals(byte[] a,
                             byte[] a2)
Returns true if the two specified arrays of bytes are equal to one another. Two arrays are considered equal if both arrays contain the same number of elements, and all corresponding pairs of elements in the two arrays are equal. In other words, two arrays are equal if they contain the same elements in the same order. Also, two array references are considered equal if both are null.

Parameters:
a - one array to be tested for equality.
a2 - the other array to be tested for equality.
Returns:
true if the two arrays are equal.

equals

public static boolean equals(boolean[] a,
                             boolean[] a2)
Returns true if the two specified arrays of booleans are equal to one another. Two arrays are considered equal if both arrays contain the same number of elements, and all corresponding pairs of elements in the two arrays are equal. In other words, two arrays are equal if they contain the same elements in the same order. Also, two array references are considered equal if both are null.

Parameters:
a - one array to be tested for equality.
a2 - the other array to be tested for equality.
Returns:
true if the two arrays are equal.

equals

public static boolean equals(double[] a,
                             double[] a2)
Returns true if the two specified arrays of doubles are equal to one another. Two arrays are considered equal if both arrays contain the same number of elements, and all corresponding pairs of elements in the two arrays are equal. In other words, two arrays are equal if they contain the same elements in the same order. Also, two array references are considered equal if both are null.

Two doubles d1 and d2 are considered equal if:

    new Double(d1).equals(new Double(d2))
(Unlike the == operator, this method considers NaN equals to itself, and 0.0d unequal to -0.0d.)

Parameters:
a - one array to be tested for equality.
a2 - the other array to be tested for equality.
Returns:
true if the two arrays are equal.
See Also:
Double.equals(Object)

equals

public static boolean equals(float[] a,
                             float[] a2)
Returns true if the two specified arrays of floats are equal to one another. Two arrays are considered equal if both arrays contain the same number of elements, and all corresponding pairs of elements in the two arrays are equal. In other words, two arrays are equal if they contain the same elements in the same order. Also, two array references are considered equal if both are null.

Two floats f1 and f2 are considered equal if:

    new Float(f1).equals(new Float(f2))
(Unlike the == operator, this method considers NaN equals to itself, and 0.0f unequal to -0.0f.)

Parameters:
a - one array to be tested for equality.
a2 - the other array to be tested for equality.
Returns:
true if the two arrays are equal.
See Also:
Float.equals(Object)

equals

public static boolean equals(Object[] a,
                             Object[] a2)
Returns true if the two specified arrays of Objects are equal to one another. The two arrays are considered equal if both arrays contain the same number of elements, and all corresponding pairs of elements in the two arrays are equal. Two objects e1 and e2 are considered equal if (e1==null ? e2==null : e1.equals(e2)). In other words, the two arrays are equal if they contain the same elements in the same order. Also, two array references are considered equal if both are null.

Parameters:
a - one array to be tested for equality.
a2 - the other array to be tested for equality.
Returns:
true if the two arrays are equal.

fill

public static void fill(long[] a,
                        long val)
Assigns the specified long value to each element of the specified array of longs.

Parameters:
a - the array to be filled.
val - the value to be stored in all elements of the array.

fill

public static void fill(long[] a,
                        int fromIndex,
                        int toIndex,
                        long val)
Assigns the specified long value to each element of the specified range of the specified array of longs. The range to be filled extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be filled is empty.)

Parameters:
a - the array to be filled.
fromIndex - the index of the first element (inclusive) to be filled with the specified value.
toIndex - the index of the last element (exclusive) to be filled with the specified value.
val - the value to be stored in all elements of the array.
Throws:
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length

fill

public static void fill(int[] a,
                        int val)
Assigns the specified int value to each element of the specified array of ints.

Parameters:
a - the array to be filled.
val - the value to be stored in all elements of the array.

fill

public static void fill(int[] a,
                        int fromIndex,
                        int toIndex,
                        int val)
Assigns the specified int value to each element of the specified range of the specified array of ints. The range to be filled extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be filled is empty.)

Parameters:
a - the array to be filled.
fromIndex - the index of the first element (inclusive) to be filled with the specified value.
toIndex - the index of the last element (exclusive) to be filled with the specified value.
val - the value to be stored in all elements of the array.
Throws:
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length

fill

public static void fill(short[] a,
                        short val)
Assigns the specified short value to each element of the specified array of shorts.

Parameters:
a - the array to be filled.
val - the value to be stored in all elements of the array.

fill

public static void fill(short[] a,
                        int fromIndex,
                        int toIndex,
                        short val)
Assigns the specified short value to each element of the specified range of the specified array of shorts. The range to be filled extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be filled is empty.)

Parameters:
a - the array to be filled.
fromIndex - the index of the first element (inclusive) to be filled with the specified value.
toIndex - the index of the last element (exclusive) to be filled with the specified value.
val - the value to be stored in all elements of the array.
Throws:
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length

fill

public static void fill(char[] a,
                        char val)
Assigns the specified char value to each element of the specified array of chars.

Parameters:
a - the array to be filled.
val - the value to be stored in all elements of the array.

fill

public static void fill(char[] a,
                        int fromIndex,
                        int toIndex,
                        char val)
Assigns the specified char value to each element of the specified range of the specified array of chars. The range to be filled extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be filled is empty.)

Parameters:
a - the array to be filled.
fromIndex - the index of the first element (inclusive) to be filled with the specified value.
toIndex - the index of the last element (exclusive) to be filled with the specified value.
val - the value to be stored in all elements of the array.
Throws:
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length

fill

public static void fill(byte[] a,
                        byte val)
Assigns the specified byte value to each element of the specified array of bytes.

Parameters:
a - the array to be filled.
val - the value to be stored in all elements of the array.

fill

public static void fill(byte[] a,
                        int fromIndex,
                        int toIndex,
                        byte val)
Assigns the specified byte value to each element of the specified range of the specified array of bytes. The range to be filled extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be filled is empty.)

Parameters:
a - the array to be filled.
fromIndex - the index of the first element (inclusive) to be filled with the specified value.
toIndex - the index of the last element (exclusive) to be filled with the specified value.
val - the value to be stored in all elements of the array.
Throws:
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length

fill

public static void fill(boolean[] a,
                        boolean val)
Assigns the specified boolean value to each element of the specified array of booleans.

Parameters:
a - the array to be filled.
val - the value to be stored in all elements of the array.

fill

public static void fill(boolean[] a,
                        int fromIndex,
                        int toIndex,
                        boolean val)
Assigns the specified boolean value to each element of the specified range of the specified array of booleans. The range to be filled extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be filled is empty.)

Parameters:
a - the array to be filled.
fromIndex - the index of the first element (inclusive) to be filled with the specified value.
toIndex - the index of the last element (exclusive) to be filled with the specified value.
val - the value to be stored in all elements of the array.
Throws:
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length

fill

public static void fill(double[] a,
                        double val)
Assigns the specified double value to each element of the specified array of doubles.

Parameters:
a - the array to be filled.
val - the value to be stored in all elements of the array.

fill

public static void fill(double[] a,
                        int fromIndex,
                        int toIndex,
                        double val)
Assigns the specified double value to each element of the specified range of the specified array of doubles. The range to be filled extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be filled is empty.)

Parameters:
a - the array to be filled.
fromIndex - the index of the first element (inclusive) to be filled with the specified value.
toIndex - the index of the last element (exclusive) to be filled with the specified value.
val - the value to be stored in all elements of the array.
Throws:
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length

fill

public static void fill(float[] a,
                        float val)
Assigns the specified float value to each element of the specified array of floats.

Parameters:
a - the array to be filled.
val - the value to be stored in all elements of the array.

fill

public static void fill(float[] a,
                        int fromIndex,
                        int toIndex,
                        float val)
Assigns the specified float value to each element of the specified range of the specified array of floats. The range to be filled extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be filled is empty.)

Parameters:
a - the array to be filled.
fromIndex - the index of the first element (inclusive) to be filled with the specified value.
toIndex - the index of the last element (exclusive) to be filled with the specified value.
val - the value to be stored in all elements of the array.
Throws:
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length

fill

public static void fill(Object[] a,
                        Object val)
Assigns the specified Object reference to each element of the specified array of Objects.

Parameters:
a - the array to be filled.
val - the value to be stored in all elements of the array.

fill

public static void fill(Object[] a,
                        int fromIndex,
                        int toIndex,
                        Object val)
Assigns the specified Object reference to each element of the specified range of the specified array of Objects. The range to be filled extends from index fromIndex, inclusive, to index toIndex, exclusive. (If fromIndex==toIndex, the range to be filled is empty.)

Parameters:
a - the array to be filled.
fromIndex - the index of the first element (inclusive) to be filled with the specified value.
toIndex - the index of the last element (exclusive) to be filled with the specified value.
val - the value to be stored in all elements of the array.
Throws:
IllegalArgumentException - if fromIndex > toIndex
ArrayIndexOutOfBoundsException - if fromIndex < 0 or toIndex > a.length

asList

public static List asList(Object[] a)
Returns a fixed-size list backed by the specified array. (Changes to the returned list "write through" to the array.) This method acts as bridge between array-based and collection-based APIs, in combination with Collection.toArray. The returned list is serializable and implements RandomAccess.

Parameters:
a - the array by which the list will be backed.
Returns:
a list view of the specified array.
See Also:
Collection.toArray()

JavaTM 2 Platform
Std. Ed. v1.4.2

Submit a bug or feature
For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Copyright 2003 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.


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