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, except where noted.

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.

Public Method Summary

static <T> List<T>
asList(T... a)
Returns a fixed-size list backed by the specified array.
static int
binarySearch(char[] a, int fromIndex, int toIndex, char key)
Searches a range of the specified array of chars 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(float[] a, int fromIndex, int toIndex, float key)
Searches a range of the specified array of floats for the specified value using the binary search algorithm.
static int
binarySearch(byte[] a, int fromIndex, int toIndex, byte key)
Searches a range of the specified array of bytes for the specified value using the binary search algorithm.
static int
binarySearch(long[] a, int fromIndex, int toIndex, long key)
Searches a range of the specified array of longs for the specified value using the binary search algorithm.
static int
binarySearch(int[] a, int fromIndex, int toIndex, int key)
Searches a range of the specified array of ints for the specified value using the binary search algorithm.
static int
binarySearch(short[] a, int fromIndex, int toIndex, short key)
Searches a range of the specified array of shorts for the specified value using the binary search algorithm.
static <T> int
binarySearch(T[] a, int fromIndex, int toIndex, T key, Comparator<? super T> c)
Searches a range of the specified array for the specified object using the binary search algorithm.
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(short[] a, short key)
Searches the specified array of shorts 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(double[] a, int fromIndex, int toIndex, double key)
Searches a range of the specified array of doubles for the specified value using the binary search algorithm.
static int
binarySearch(Object[] a, int fromIndex, int toIndex, Object key)
Searches a range of the specified array for the specified object 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(int[] a, int key)
Searches the specified array of ints 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 <T> int
binarySearch(T[] a, T key, Comparator<? super T> c)
Searches the specified array for the specified object 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 double[]
copyOf(double[] original, int newLength)
Copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length.
static float[]
copyOf(float[] original, int newLength)
Copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length.
static boolean[]
copyOf(boolean[] original, int newLength)
Copies the specified array, truncating or padding with false (if necessary) so the copy has the specified length.
static int[]
copyOf(int[] original, int newLength)
Copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length.
static long[]
copyOf(long[] original, int newLength)
Copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length.
static short[]
copyOf(short[] original, int newLength)
Copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length.
static <T, U> T[]
copyOf(U[] original, int newLength, Class<? extends T[]> newType)
Copies the specified array, truncating or padding with nulls (if necessary) so the copy has the specified length.
static <T> T[]
copyOf(T[] original, int newLength)
Copies the specified array, truncating or padding with nulls (if necessary) so the copy has the specified length.
static char[]
copyOf(char[] original, int newLength)
Copies the specified array, truncating or padding with null characters (if necessary) so the copy has the specified length.
static byte[]
copyOf(byte[] original, int newLength)
Copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length.
static double[]
copyOfRange(double[] original, int from, int to)
Copies the specified range of the specified array into a new array.
static <T> T[]
copyOfRange(T[] original, int from, int to)
Copies the specified range of the specified array into a new array.
static char[]
copyOfRange(char[] original, int from, int to)
Copies the specified range of the specified array into a new array.
static float[]
copyOfRange(float[] original, int from, int to)
Copies the specified range of the specified array into a new array.
static long[]
copyOfRange(long[] original, int from, int to)
Copies the specified range of the specified array into a new array.
static int[]
copyOfRange(int[] original, int from, int to)
Copies the specified range of the specified array into a new array.
static boolean[]
copyOfRange(boolean[] original, int from, int to)
Copies the specified range of the specified array into a new array.
static <T, U> T[]
copyOfRange(U[] original, int from, int to, Class<? extends T[]> newType)
Copies the specified range of the specified array into a new array.
static short[]
copyOfRange(short[] original, int from, int to)
Copies the specified range of the specified array into a new array.
static byte[]
copyOfRange(byte[] original, int from, int to)
Copies the specified range of the specified array into a new array.
static boolean
deepEquals(Object[] a1, Object[] a2)
Returns true if the two specified arrays are deeply equal to one another.
static int
deepHashCode(Object[] a)
Returns a hash code based on the "deep contents" of the specified array.
static String
deepToString(Object[] a)
Returns a string representation of the "deep contents" of the specified array.
static boolean
equals(Object[] a, Object[] a2)
Returns true if the two specified arrays of Objects 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(long[] a, long[] a2)
Returns true if the two specified arrays of longs 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(boolean[] a, boolean[] a2)
Returns true if the two specified arrays of booleans 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(float[] a, float[] a2)
Returns true if the two specified arrays of floats 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 boolean
equals(byte[] a, byte[] a2)
Returns true if the two specified arrays of bytes are equal to one another.
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(float[] a, float val)
Assigns the specified float value to each element of the specified array of floats.
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(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(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(Object[] a, Object val)
Assigns the specified Object reference to each element of the specified array of Objects.
static void
fill(double[] a, double val)
Assigns the specified double value to each element of the specified array of doubles.
static void
fill(long[] a, long val)
Assigns the specified long value to each element of the specified array of longs.
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(byte[] a, byte val)
Assigns the specified byte value to each element of the specified array of bytes.
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(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(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(boolean[] a, boolean val)
Assigns the specified boolean value to each element of the specified array of booleans.
static void
fill(short[] a, short val)
Assigns the specified short value to each element of the specified array of shorts.
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(int[] a, int val)
Assigns the specified int value to each element of the specified array of ints.
static int
hashCode(byte[] a)
Returns a hash code based on the contents of the specified array.
static int
hashCode(boolean[] a)
Returns a hash code based on the contents of the specified array.
static int
hashCode(char[] a)
Returns a hash code based on the contents of the specified array.
static int
hashCode(long[] a)
Returns a hash code based on the contents of the specified array.
static int
hashCode(int[] a)
Returns a hash code based on the contents of the specified array.
static int
hashCode(float[] a)
Returns a hash code based on the contents of the specified array.
static int
hashCode(short[] a)
Returns a hash code based on the contents of the specified array.
static int
hashCode(Object[] a)
Returns a hash code based on the contents of the specified array.
static int
hashCode(double[] a)
Returns a hash code based on the contents of the specified array.
static <T> void
parallelPrefix(T[] array, int fromIndex, int toIndex, BinaryOperator<T> op)
Performs parallelPrefix(Object[], BinaryOperator) for the given subrange of the array.
static <T> void
parallelPrefix(T[] array, BinaryOperator<T> op)
Cumulates, in parallel, each element of the given array in place, using the supplied function.
static void
parallelPrefix(long[] array, LongBinaryOperator op)
Cumulates, in parallel, each element of the given array in place, using the supplied function.
static void
parallelPrefix(long[] array, int fromIndex, int toIndex, LongBinaryOperator op)
Performs parallelPrefix(long[], LongBinaryOperator) for the given subrange of the array.
static void
parallelPrefix(int[] array, int fromIndex, int toIndex, IntBinaryOperator op)
Performs parallelPrefix(int[], IntBinaryOperator) for the given subrange of the array.
static void
parallelPrefix(double[] array, int fromIndex, int toIndex, DoubleBinaryOperator op)
Performs parallelPrefix(double[], DoubleBinaryOperator) for the given subrange of the array.
static void
parallelPrefix(double[] array, DoubleBinaryOperator op)
Cumulates, in parallel, each element of the given array in place, using the supplied function.
static void
parallelPrefix(int[] array, IntBinaryOperator op)
Cumulates, in parallel, each element of the given array in place, using the supplied function.
static void
parallelSetAll(double[] array, IntToDoubleFunction generator)
Set all elements of the specified array, in parallel, using the provided generator function to compute each element.
static void
parallelSetAll(int[] array, IntUnaryOperator generator)
Set all elements of the specified array, in parallel, using the provided generator function to compute each element.
static void
parallelSetAll(long[] array, IntToLongFunction generator)
Set all elements of the specified array, in parallel, using the provided generator function to compute each element.
static <T> void
parallelSetAll(T[] array, IntFunction<? extends T> generator)
Set all elements of the specified array, in parallel, using the provided generator function to compute each element.
static <T> void
parallelSort(T[] a, Comparator<? super T> cmp)
Sorts the specified array of objects according to the order induced by the specified comparator.
static void
parallelSort(long[] a)
Sorts the specified array into ascending numerical order.
static void
parallelSort(short[] a)
Sorts the specified array into ascending numerical order.
static void
parallelSort(double[] a)
Sorts the specified array into ascending numerical order.
static void
parallelSort(char[] a)
Sorts the specified array into ascending numerical order.
static void
parallelSort(double[] a, int fromIndex, int toIndex)
Sorts the specified range of the array into ascending numerical order.
static <T extends Comparable<? super T>> void
parallelSort(T[] a)
Sorts the specified array of objects into ascending order, according to the {@linkplain Comparable natural ordering} of its elements.
static void
parallelSort(float[] a)
Sorts the specified array into ascending numerical order.
static void
parallelSort(byte[] a)
Sorts the specified array into ascending numerical order.
static void
parallelSort(char[] a, int fromIndex, int toIndex)
Sorts the specified range of the array into ascending numerical order.
static void
parallelSort(int[] a)
Sorts the specified array into ascending numerical order.
static void
parallelSort(long[] a, int fromIndex, int toIndex)
Sorts the specified range of the array into ascending numerical order.
static void
parallelSort(float[] a, int fromIndex, int toIndex)
Sorts the specified range of the array into ascending numerical order.
static void
parallelSort(int[] a, int fromIndex, int toIndex)
Sorts the specified range of the array into ascending numerical order.
static void
parallelSort(byte[] a, int fromIndex, int toIndex)
Sorts the specified range of the array into ascending numerical order.
static void
parallelSort(short[] a, int fromIndex, int toIndex)
Sorts the specified range of the array into ascending numerical order.
static <T extends Comparable<? super T>> void
parallelSort(T[] a, int fromIndex, int toIndex)
Sorts the specified range of the specified array of objects into ascending order, according to the {@linkplain Comparable natural ordering} of its elements.
static <T> void
parallelSort(T[] a, int fromIndex, int toIndex, Comparator<? super T> cmp)
Sorts the specified range of the specified array of objects according to the order induced by the specified comparator.
static <T> void
setAll(T[] array, IntFunction<? extends T> generator)
Set all elements of the specified array, using the provided generator function to compute each element.
static void
setAll(double[] array, IntToDoubleFunction generator)
Set all elements of the specified array, using the provided generator function to compute each element.
static void
setAll(long[] array, IntToLongFunction generator)
Set all elements of the specified array, using the provided generator function to compute each element.
static void
setAll(int[] array, IntUnaryOperator generator)
Set all elements of the specified array, using the provided generator function to compute each element.
static <T> void
sort(T[] a, int fromIndex, int toIndex, Comparator<? super T> c)
Sorts the specified range of the specified array of objects according to the order induced by the specified comparator.
static void
sort(int[] a)
Sorts the specified array into ascending numerical order.
static void
sort(long[] a, int fromIndex, int toIndex)
Sorts the specified range of the array into ascending order.
static void
sort(double[] a)
Sorts the specified array into ascending numerical order.
static void
sort(short[] a)
Sorts the specified array into ascending numerical order.
static void
sort(char[] a, int fromIndex, int toIndex)
Sorts the specified range of the array into ascending order.
static void
sort(long[] a)
Sorts the specified array into ascending numerical order.
static void
sort(float[] a, int fromIndex, int toIndex)
Sorts the specified range of the array into ascending order.
static void
sort(short[] a, int fromIndex, int toIndex)
Sorts the specified range of the array into ascending order.
static <T> void
sort(T[] a, Comparator<? super T> c)
Sorts the specified array of objects according to the order induced by the specified comparator.
static void
sort(byte[] a)
Sorts the specified array into ascending numerical order.
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 {@linkplain Comparable natural ordering} of its elements.
static void
sort(char[] a)
Sorts the specified array into ascending numerical order.
static void
sort(double[] a, int fromIndex, int toIndex)
Sorts the specified range of the array into ascending order.
static void
sort(Object[] a)
Sorts the specified array of objects into ascending order, according to the {@linkplain Comparable natural ordering} of its elements.
static void
sort(int[] a, int fromIndex, int toIndex)
Sorts the specified range of the array into ascending order.
static void
sort(byte[] a, int fromIndex, int toIndex)
Sorts the specified range of the array into ascending order.
static void
sort(float[] a)
Sorts the specified array into ascending numerical order.
static Spliterator.OfLong
spliterator(long[] array, int startInclusive, int endExclusive)
Returns a Spliterator.OfLong covering the specified range of the specified array.
static Spliterator.OfLong
spliterator(long[] array)
Returns a Spliterator.OfLong covering all of the specified array.
static Spliterator.OfDouble
spliterator(double[] array)
Returns a Spliterator.OfDouble covering all of the specified array.
static Spliterator.OfInt
spliterator(int[] array, int startInclusive, int endExclusive)
Returns a Spliterator.OfInt covering the specified range of the specified array.
static <T> Spliterator<T>
spliterator(T[] array)
Returns a Spliterator covering all of the specified array.
static Spliterator.OfInt
spliterator(int[] array)
Returns a Spliterator.OfInt covering all of the specified array.
static <T> Spliterator<T>
spliterator(T[] array, int startInclusive, int endExclusive)
Returns a Spliterator covering the specified range of the specified array.
static Spliterator.OfDouble
spliterator(double[] array, int startInclusive, int endExclusive)
Returns a Spliterator.OfDouble covering the specified range of the specified array.
static IntStream
stream(int[] array)
Returns a sequential IntStream with the specified array as its source.
static LongStream
stream(long[] array)
Returns a sequential LongStream with the specified array as its source.
static <T> Stream<T>
stream(T[] array)
Returns a sequential Stream with the specified array as its source.
static DoubleStream
stream(double[] array, int startInclusive, int endExclusive)
Returns a sequential DoubleStream with the specified range of the specified array as its source.
static DoubleStream
stream(double[] array)
Returns a sequential DoubleStream with the specified array as its source.
static IntStream
stream(int[] array, int startInclusive, int endExclusive)
Returns a sequential IntStream with the specified range of the specified array as its source.
static <T> Stream<T>
stream(T[] array, int startInclusive, int endExclusive)
Returns a sequential Stream with the specified range of the specified array as its source.
static LongStream
stream(long[] array, int startInclusive, int endExclusive)
Returns a sequential LongStream with the specified range of the specified array as its source.
static String
toString(float[] a)
Returns a string representation of the contents of the specified array.
static String
toString(int[] a)
Returns a string representation of the contents of the specified array.
static String
toString(Object[] a)
Returns a string representation of the contents of the specified array.
static String
toString(long[] a)
Returns a string representation of the contents of the specified array.
static String
toString(boolean[] a)
Returns a string representation of the contents of the specified array.
static String
toString(double[] a)
Returns a string representation of the contents of the specified array.
static String
toString(short[] a)
Returns a string representation of the contents of the specified array.
static String
toString(char[] a)
Returns a string representation of the contents of the specified array.
static String
toString(byte[] a)
Returns a string representation of the contents of the specified array.

Inherited Method Summary

Public Methods

public static List<T> asList (T... 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.

This method also provides a convenient way to create a fixed-size list initialized to contain several elements:

     List<String> stooges = Arrays.asList("Larry", "Moe", "Curly");
 

Parameters
a the array by which the list will be backed
Returns
  • a list view of the specified array

public static int binarySearch (char[] a, int fromIndex, int toIndex, char key)

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

Parameters
a the array to be searched
fromIndex the index of the first element (inclusive) to be searched
toIndex the index of the last element (exclusive) to be searched
key the value to be searched for
Returns
  • index of the search key, if it is contained in the array within the specified range; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the array: the index of the first element in the range greater than the key, or toIndex if all elements in the range 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
IllegalArgumentException if fromIndex > toIndex
ArrayIndexOutOfBoundsException if fromIndex < 0 or toIndex > a.length

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(long[]) method) 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 array; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the array: the index of the first element greater than the key, or a.length if all elements in the array 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.

public static int binarySearch (float[] a, int fromIndex, int toIndex, float key)

Searches a range of the specified array of floats for the specified value using the binary search algorithm. The range must be sorted (as by the sort(float[], int, int) method) prior to making this call. If it is not sorted, the results are undefined. If the range 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
fromIndex the index of the first element (inclusive) to be searched
toIndex the index of the last element (exclusive) to be searched
key the value to be searched for
Returns
  • index of the search key, if it is contained in the array within the specified range; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the array: the index of the first element in the range greater than the key, or toIndex if all elements in the range 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
IllegalArgumentException if fromIndex > toIndex
ArrayIndexOutOfBoundsException if fromIndex < 0 or toIndex > a.length

public static int binarySearch (byte[] a, int fromIndex, int toIndex, byte key)

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

Parameters
a the array to be searched
fromIndex the index of the first element (inclusive) to be searched
toIndex the index of the last element (exclusive) to be searched
key the value to be searched for
Returns
  • index of the search key, if it is contained in the array within the specified range; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the array: the index of the first element in the range greater than the key, or toIndex if all elements in the range 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
IllegalArgumentException if fromIndex > toIndex
ArrayIndexOutOfBoundsException if fromIndex < 0 or toIndex > a.length

public static int binarySearch (long[] a, int fromIndex, int toIndex, long key)

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

Parameters
a the array to be searched
fromIndex the index of the first element (inclusive) to be searched
toIndex the index of the last element (exclusive) to be searched
key the value to be searched for
Returns
  • index of the search key, if it is contained in the array within the specified range; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the array: the index of the first element in the range greater than the key, or toIndex if all elements in the range 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
IllegalArgumentException if fromIndex > toIndex
ArrayIndexOutOfBoundsException if fromIndex < 0 or toIndex > a.length

public static int binarySearch (int[] a, int fromIndex, int toIndex, int key)

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

Parameters
a the array to be searched
fromIndex the index of the first element (inclusive) to be searched
toIndex the index of the last element (exclusive) to be searched
key the value to be searched for
Returns
  • index of the search key, if it is contained in the array within the specified range; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the array: the index of the first element in the range greater than the key, or toIndex if all elements in the range 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
IllegalArgumentException if fromIndex > toIndex
ArrayIndexOutOfBoundsException if fromIndex < 0 or toIndex > a.length

public static int binarySearch (short[] a, int fromIndex, int toIndex, short key)

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

Parameters
a the array to be searched
fromIndex the index of the first element (inclusive) to be searched
toIndex the index of the last element (exclusive) to be searched
key the value to be searched for
Returns
  • index of the search key, if it is contained in the array within the specified range; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the array: the index of the first element in the range greater than the key, or toIndex if all elements in the range 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
IllegalArgumentException if fromIndex > toIndex
ArrayIndexOutOfBoundsException if fromIndex < 0 or toIndex > a.length

public static int binarySearch (T[] a, int fromIndex, int toIndex, T key, Comparator<? super T> c)

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

Parameters
a the array to be searched
fromIndex the index of the first element (inclusive) to be searched
toIndex the index of the last element (exclusive) 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' {@linkplain Comparable natural ordering} should be used.
Returns
  • index of the search key, if it is contained in the array within the specified range; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the array: the index of the first element in the range greater than the key, or toIndex if all elements in the range 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 range contains elements that are not mutually comparable using the specified comparator, or the search key is not comparable to the elements in the range using this comparator.
IllegalArgumentException if fromIndex > toIndex
ArrayIndexOutOfBoundsException if fromIndex < 0 or toIndex > a.length

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(byte[]) method) 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 array; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the array: the index of the first element greater than the key, or a.length if all elements in the array 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.

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(short[]) method) 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 array; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the array: the index of the first element greater than the key, or a.length if all elements in the array 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.

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 {@linkplain Comparable natural ordering} of its elements (as by the sort(Object[]) method) 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 ordering 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 array; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the array: the index of the first element greater than the key, or a.length if all elements in the array 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 is not comparable to the elements of the array.

public static int binarySearch (double[] a, int fromIndex, int toIndex, double key)

Searches a range of the specified array of doubles for the specified value using the binary search algorithm. The range must be sorted (as by the sort(double[], int, int) method) prior to making this call. If it is not sorted, the results are undefined. If the range 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
fromIndex the index of the first element (inclusive) to be searched
toIndex the index of the last element (exclusive) to be searched
key the value to be searched for
Returns
  • index of the search key, if it is contained in the array within the specified range; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted into the array: the index of the first element in the range greater than the key, or toIndex if all elements in the range 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
IllegalArgumentException if fromIndex > toIndex
ArrayIndexOutOfBoundsException if fromIndex < 0 or toIndex > a.length

public static int binarySearch (Object[] a, int fromIndex, int toIndex, Object key)

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