is new.
java.lang.Objectjava.util.Arrays
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.
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 .
| Method Summary | ||||
|---|---|---|---|---|
static
|
asList
(T[] 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
(short[] a, short key) Searches the specified array of shorts for the specified value using the binary search algorithm. |
|||
static
|
binarySearch
(T[] a, T key,
Comparator
<? super T> c)
Searches the specified array for the specified object using the binary search algorithm.
|
|||
static boolean
|
deepEquals
(
Object
[] a1,
Object
Returns
true
if the two specified arrays are
deeply equal
to one another.
|
|||
static int
|
deepHashCode
(
Object
Returns a hash code based on the "deep contents" of the specified array.
|
|||
static
String
|
deepToString
(
Object
Returns a string representation of the "deep contents" of the specified array.
|
|||
| 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 int
|
hashCode
(boolean[] a)
Returns a hash code based on the contents of the specified array.
|
|||
static int
|
hashCode
(byte[] 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
(double[] 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
(int[] 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
(
Object
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 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, 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
(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. |
|||
static
|
sort
(T[] a,
Comparator
<? super T> c)
Sorts the specified array of objects according to the order induced by the specified comparator.
|
|||
static
|
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
String
|
toString
(boolean[] 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.
|
|||
static
String
|
toString
(char[] 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
(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
(long[] a)
Returns a string representation of the contents of the specified array.
|
|||
static
String
|
toString
(
Object
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.
|
|||
| Methods inherited from class java.lang. Object |
|---|
| clone , equals , finalize , getClass , hashCode , notify , notifyAll , toString , wait , wait , wait |
| Method Detail |
|---|
public static void sort(long[] a)
public static void sort(long[] a,
int fromIndex,
int toIndex)
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.
public static void sort(int[] a)
public static void sort(int[] a,
int fromIndex,
int toIndex)
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.
public static void sort(short[] a)
public static void sort(short[] a,
int fromIndex,
int toIndex)
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.
public static void sort(char[] a)
public static void sort(char[] a,
int fromIndex,
int toIndex)
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.
public static void sort(byte[] a)
public static void sort(byte[] a,
int fromIndex,
int toIndex)
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.
public static void sort(double[] a)
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.
public static void sort(double[] a,
int fromIndex,
int toIndex)
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.
public static void sort(float[] a)
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.
public static void sort(float[] a,
int fromIndex,
int toIndex)
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.
public static void sort(Object[] a)
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.
public static void sort(Object[] a,
int fromIndex,
int toIndex)
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.
public static<T> void sort
(T[] a,
Comparator
(Object<? super T> c)
[] a,Comparatorc)
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.
public static<T> void sort
(T[] a, int fromIndex, int toIndex,
Comparator
(Object<? super T> c)
[] a, int fromIndex, int toIndex,Comparatorc)
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.
public static int binarySearch(long[] a,
long key)
public static int binarySearch(int[] a,
int key)
public static int binarySearch(short[] a,
short key)
public static int binarySearch(char[] a,
char key)
public static int binarySearch(byte[] a,
byte key)
public static int binarySearch(double[] a,
double key)
public static int binarySearch(float[] a,
float key)
public static int binarySearch(Object[] a,
Object key)
public static<T> int binarySearch
(T[] a, T key,
Comparator
(Object<? super T> c)
[] a,Objectkey,Comparatorc)
sort(Object[], Comparator)
public static boolean equals(long[] a,
long[] a2)
public static boolean equals(int[] a,
int[] a2)
public static boolean equals(short[] a,
short[] a2)
public static boolean equals(char[] a,
char[] a2)
public static boolean equals(byte[] a,
byte[] a2)
public static boolean equals(boolean[] a,
boolean[] a2)
public static boolean equals(double[] a,
double[] a2)
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.)
public static boolean equals(float[] a,
float[] a2)
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.)
public static boolean equals(Object[] a,
Object[] a2)
public static void fill(long[] a,
long val)
public static void fill(long[] a,
int fromIndex,
int toIndex,
long val)
public static void fill(int[] a,
int val)
public static void fill(int[] a,
int fromIndex,
int toIndex,
int val)
public static void fill(short[] a,
short val)
public static void fill(short[] a,
int fromIndex,
int toIndex,
short val)
public static void fill(char[] a,
char val)
public static void fill(char[] a,
int fromIndex,
int toIndex,
char val)
public static void fill(byte[] a,
byte val)
public static void fill(byte[] a,
int fromIndex,
int toIndex,
byte val)
public static void fill(boolean[] a,
boolean val)
public static void fill(boolean[] a,
int fromIndex,
int toIndex,
boolean val)
public static void fill(double[] a,
double val)
public static void fill(double[] a,
int fromIndex,
int toIndex,
double val)
public static void fill(float[] a,
float val)
public static void fill(float[] a,
int fromIndex,
int toIndex,
float val)
public static void fill(Object[] a,
Object val)
public static void fill(Object[] a,
int fromIndex,
int toIndex,
Object val)
public static<T> List
<T> asList
(T[] a)
(Object[] a)
hashCode
public static int
hashCode
(long[] a)
Returns a hash code based on the contents of the specified array. For any two
long
arrays
a
and
b
such that
Arrays.equals(a, b)
, it is also the case that
Arrays.hashCode(a) == Arrays.hashCode(b)
.
The value returned by this method is the same value that would be obtained by invoking the
hashCode
method on a
List
containing a sequence of
Long
instances representing the elements of
a
in the same order. If
a
is
null
, this method returns 0.
Parameters:
the - array whose hash value to compute
Returns:
a content-based hash code for
a
Since:
1.5
hashCode
public static int
hashCode
(int[] a)
Returns a hash code based on the contents of the specified array. For any two non-null
int
arrays
a
and
b
such that
Arrays.equals(a, b)
, it is also the case that
Arrays.hashCode(a) == Arrays.hashCode(b)
.
The value returned by this method is the same value that would be obtained by invoking the
hashCode
method on a
List
containing a sequence of
Integer
instances representing the elements of
a
in the same order. If
a
is
null
, this method returns 0.
Parameters:
the - array whose hash value to compute
Returns:
a content-based hash code for
a
Since:
1.5
hashCode
public static int
hashCode
(short[] a)
Returns a hash code based on the contents of the specified array. For any two
short
arrays
a
and
b
such that
Arrays.equals(a, b)
, it is also the case that
Arrays.hashCode(a) == Arrays.hashCode(b)
.
The value returned by this method is the same value that would be obtained by invoking the
hashCode
method on a
List
containing a sequence of
Short
instances representing the elements of
a
in the same order. If
a
is
null
, this method returns 0.
Parameters:
the - array whose hash value to compute
Returns:
a content-based hash code for
a
Since:
1.5
hashCode
public static int
hashCode
(char[] a)
Returns a hash code based on the contents of the specified array. For any two
char
arrays
a
and
b
such that
Arrays.equals(a, b)
, it is also the case that
Arrays.hashCode(a) == Arrays.hashCode(b)
.
The value returned by this method is the same value that would be obtained by invoking the
hashCode
method on a
List
containing a sequence of
Character
instances representing the elements of
a
in the same order. If
a
is
null
, this method returns 0.
Parameters:
the - array whose hash value to compute
Returns:
a content-based hash code for
a
Since:
1.5
hashCode
public static int
hashCode
(byte[] a)
Returns a hash code based on the contents of the specified array. For any two
byte
arrays
a
and
b
such that
Arrays.equals(a, b)
, it is also the case that
Arrays.hashCode(a) == Arrays.hashCode(b)
.
The value returned by this method is the same value that would be obtained by invoking the
hashCode
method on a
List
containing a sequence of
Byte
instances representing the elements of
a
in the same order. If
a
is
null
, this method returns 0.
Parameters:
the - array whose hash value to compute
Returns:
a content-based hash code for
a
Since:
1.5
hashCode
public static int
hashCode
(boolean[] a)
Returns a hash code based on the contents of the specified array. For any two
boolean
arrays
a
and
b
such that
Arrays.equals(a, b)
, it is also the case that
Arrays.hashCode(a) == Arrays.hashCode(b)
.
The value returned by this method is the same value that would be obtained by invoking the
hashCode
method on a
List
containing a sequence of
Boolean
instances representing the elements of
a
in the same order. If
a
is
null
, this method returns 0.
Parameters:
the - array whose hash value to compute
Returns:
a content-based hash code for
a
Since:
1.5
hashCode
public static int
hashCode
(float[] a)
Returns a hash code based on the contents of the specified array. For any two
float
arrays
a
and
b
such that
Arrays.equals(a, b)
, it is also the case that
Arrays.hashCode(a) == Arrays.hashCode(b)
.
The value returned by this method is the same value that would be obtained by invoking the
hashCode
method on a
List
containing a sequence of
Float
instances representing the elements of
a
in the same order. If
a
is
null
, this method returns 0.
Parameters:
the - array whose hash value to compute
Returns:
a content-based hash code for
a
Since:
1.5
hashCode
public static int
hashCode
(double[] a)
Returns a hash code based on the contents of the specified array. For any two
double
arrays
a
and
b
such that
Arrays.equals(a, b)
, it is also the case that
Arrays.hashCode(a) == Arrays.hashCode(b)
.
The value returned by this method is the same value that would be obtained by invoking the
hashCode
method on a
List
containing a sequence of
Double
instances representing the elements of
a
in the same order. If
a
is
null
, this method returns 0.
Parameters:
the - array whose hash value to compute
Returns:
a content-based hash code for
a
Since:
1.5
hashCode
public static int
hashCode
(
Object
[] a)
Returns a hash code based on the contents of the specified array. If the array contains other arrays as elements, the hash code is based on their identities rather than their contents. It is therefore acceptable to invoke this method on an array that contains itself as an element, either directly or indirectly through one or more levels of arrays.
For any two arrays
a
and
b
such that
Arrays.equals(a, b)
, it is also the case that
Arrays.hashCode(a) == Arrays.hashCode(b)
.
The value returned by this method is equal to the value that would be returned by
Arrays.asList(a).hashCode()
, unless
a
is
null
, in which case
0
is returned.
Parameters:
the - array whose content-based hash code to compute
Returns:
a content-based hash code for
a
Since:
1.5
See Also:
deepHashCode(Object[])
deepHashCode
public static int
deepHashCode
(
Object
[] a)
Returns a hash code based on the "deep contents" of the specified array. If the array contains other arrays as elements, the hash code is based on their contents and so on, ad infinitum. It is therefore unacceptable to invoke this method on an array that contains itself as an element, either directly or indirectly through one or more levels of arrays. The behavior of such an invocation is undefined.
For any two arrays
a
and
b
such that
Arrays.deepEquals(a, b)
, it is also the case that
Arrays.deepHashCode(a) == Arrays.deepHashCode(b)
.
The computation of the value returned by this method is similar to that of the value returned by
List.hashCode()
on a list containing the same elements as
a
in the same order, with one difference: If an element
e
of
a
is itself an array, its hash code is computed not by calling
e.hashCode()
, but as by calling the appropriate overloading of
Arrays.hashCode(e)
if
e
is an array of a primitive type, or as by calling
Arrays.deepHashCode(e)
recursively if
e
is an array of a reference type. If
a
is
null
, this method returns 0.
Parameters:
the - array whose deep-content-based hash code to compute
Returns:
a deep-content-based hash code for
a
Since:
1.5
See Also:
hashCode(Object[])
deepEquals
public static boolean
deepEquals
(
Object
[] a1,
Object
[] a2)
Returns
true
if the two specified arrays are
deeply equal
to one another. Unlike the @link{#equals{Object[],Object[]) method, this method is appropriate for use with nested arrays of arbitrary depth.
Two array references are considered deeply equal if both are
null
, or if they refer to arrays that contain the same number of elements and all corresponding pairs of elements in the two arrays are deeply equal.
Two possibly
null
elements
e1
and
e2
are deeply equal if any of the following conditions hold:
e1
and
e2
are both arrays of object reference types, and
Arrays.deepEquals(e1, e2) would return true
e1
and
e2
are arrays of the same primitive type, and the appropriate overloading of
Arrays.equals(e1, e2)
would return true.
e1 == e2
e1.equals(e2)
would return true.
Note that this definition permits
null
elements at any depth.
If either of the specified arrays contain themselves as elements either directly or indirectly through one or more levels of arrays, the behavior of this method is undefined.
Parameters:
a1 - one array to be tested for equality
a2 - the other array to be tested for equality
Returns:
true
if the two arrays are equal
Since:
1.5
See Also:
equals(Object[],Object[])
toString
public static
String
toString
(long[] a)
Returns a string representation of the contents of the specified array. The string representation consists of a list of the array's elements, enclosed in square brackets (
"[]"
). Adjacent elements are separated by the characters
", "
(a comma followed by a space). Elements are converted to strings as by
String.valueOf(long)
. Returns
"null"
if
a
is
null
.
Parameters:
the - array whose string representation to return
Returns:
a string representation of
a
Since:
1.5
toString
public static
String
toString
(int[] a)
Returns a string representation of the contents of the specified array. The string representation consists of a list of the array's elements, enclosed in square brackets (
"[]"
). Adjacent elements are separated by the characters
", "
(a comma followed by a space). Elements are converted to strings as by
String.valueOf(int)
. Returns
"null"
if
a
is
null
.
Parameters:
the - array whose string representation to return
Returns:
a string representation of
a
Since:
1.5
toString
public static
String
toString
(short[] a)
Returns a string representation of the contents of the specified array. The string representation consists of a list of the array's elements, enclosed in square brackets (
"[]"
). Adjacent elements are separated by the characters
", "
(a comma followed by a space). Elements are converted to strings as by
String.valueOf(short)
. Returns
"null"
if
a
is
null
.
Parameters:
the - array whose string representation to return
Returns:
a string representation of
a
Since:
1.5
toString
public static
String
toString
(char[] a)
Returns a string representation of the contents of the specified array. The string representation consists of a list of the array's elements, enclosed in square brackets (
"[]"
). Adjacent elements are separated by the characters
", "
(a comma followed by a space). Elements are converted to strings as by
String.valueOf(char)
. Returns
"null"
if
a
is
null
.
Parameters:
the - array whose string representation to return
Returns:
a string representation of
a
Since:
1.5
toString
public static
String
toString
(byte[] a)
Returns a string representation of the contents of the specified array. The string representation consists of a list of the array's elements, enclosed in square brackets (
"[]"
). Adjacent elements are separated by the characters
", "
(a comma followed by a space). Elements are converted to strings as by
String.valueOf(byte)
. Returns
"null"
if
a
is
null
.
Parameters:
the - array whose string representation to return
Returns:
a string representation of
a
Since:
1.5
toString
public static
String
toString
(boolean[] a)
Returns a string representation of the contents of the specified array. The string representation consists of a list of the array's elements, enclosed in square brackets (
"[]"
). Adjacent elements are separated by the characters
", "
(a comma followed by a space). Elements are converted to strings as by
String.valueOf(boolean)
. Returns
"null"
if
a
is
null
.
Parameters:
the - array whose string representation to return
Returns:
a string representation of
a
Since:
1.5
toString
public static
String
toString
(float[] a)
Returns a string representation of the contents of the specified array. The string representation consists of a list of the array's elements, enclosed in square brackets (
"[]"
). Adjacent elements are separated by the characters
", "
(a comma followed by a space). Elements are converted to strings as by
String.valueOf(float)
. Returns
"null"
if
a
is
null
.
Parameters:
the - array whose string representation to return
Returns:
a string representation of
a
Since:
1.5
toString
public static
String
toString
(double[] a)
Returns a string representation of the contents of the specified array. The string representation consists of a list of the array's elements, enclosed in square brackets (
"[]"
). Adjacent elements are separated by the characters
", "
(a comma followed by a space). Elements are converted to strings as by
String.valueOf(double)
. Returns
"null"
if
a
is
null
.
Parameters:
the - array whose string representation to return
Returns:
a string representation of
a
Since:
1.5
toString
public static
String
toString
(
Object
[] a)
Returns a string representation of the contents of the specified array. If the array contains other arrays as elements, they are converted to strings by the
Object.toString()
method inherited from
Object
, which describes their
identities
rather than their contents.
The value returned by this method is equal to the value that would be returned by
Arrays.asList(a).toString()
, unless
a
is
null
, in which case
"null"
is returned.
Parameters:
the - array whose string representation to return
Returns:
a string representation of
a
Since:
1.5
See Also:
#deepToString()
deepToString
public static
String
deepToString
(
Object
[] a)
Returns a string representation of the "deep contents" of the specified array. If the array contains other arrays as elements, the string representation contains their contents and so on. This method is designed for converting multidimensional arrays to strings.
The string representation consists of a list of the array's elements, enclosed in square brackets (
"[]"
). Adjacent elements are separated by the characters
", "
(a comma followed by a space). Elements are converted to strings as by
String.valueOf(Object)
, unless they are themselves arrays.
If an element
e
is an array of a primitive type, it is converted to a string as by invoking the appropriate overloading of
Arrays.toString(e)
. If an element
e
is an array of a reference type, it is converted to a string as by invoking this method recursively.
To avoid infinite recursion, if the specified array contains itself as an element, or contains an indirect reference to itself through one or more levels of arrays, the self-reference is converted to the string
"[...]"
. For example, an array containing only a reference to itself would be rendered as
"[[...]]"
.
This method returns
"null"
if the specified array is
null
.
Parameters:
the - array whose string representation to return
Returns:
a string representation of
a
Since:
1.5
See Also:
toString(Object[])