cn.wensiqun.asmsupport.core.utils.lang

类 ArrayUtils

java.lang.Object

cn.wensiqun.asmsupport.core.utils.lang.ArrayUtils

public class ArrayUtils
extends Object

字段概要

字段

限定符和类型	字段和说明
static int[]	EMPTY_INT_ARRAY An empty immutable int array.
static String[]	EMPTY_STRING_ARRAY An empty immutable String array.
static int	INDEX_NOT_FOUND The index value when an element is not found in a list or array: -1.

构造器概要

构造器

构造器和说明
ArrayUtils()

方法概要

方法

限定符和类型	方法和说明
static int[]	add(int[] array, int element) Copies the given array and adds the given element at the end of the new array.
static <T> T[]	add(T[] array, T element) Copies the given array and adds the given element at the end of the new array.
static boolean	contains(Object[] array, Object objectToFind) Checks if the object is in the given array.
static int	getLength(Object array) Returns the length of the specified array.
static int	indexOf(Object[] array, Object objectToFind) Finds the index of the given object in the array.
static int	indexOf(Object[] array, Object objectToFind, int startIndex) Finds the index of the given object in the array starting at the given index.
static <T> boolean	isEmpty(T[] array) Checks if an array of Objects is empty or null.
static <T> boolean	isNotEmpty(T[] array) Checks if an array of Objects is not empty or not null.
static boolean	isSameLength(Object[] array1, Object[] array2) Checks whether two arrays are the same length, treating null arrays as length 0.
static int[]	subarray(int[] array, int startIndexInclusive, int endIndexExclusive) Produces a new int array containing the elements between the start and end indices.
static <T> T[]	subarray(T[] array, int startIndexInclusive, int endIndexExclusive) Produces a new array containing the elements between the start and end indices.
static String	toString(Object array) Outputs an array as a String, treating null as an empty array.

从类继承的方法 java.lang.Object

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

字段详细资料

EMPTY_STRING_ARRAY

public static final String[] EMPTY_STRING_ARRAY

An empty immutable String array.

EMPTY_INT_ARRAY

public static final int[] EMPTY_INT_ARRAY

An empty immutable int array.

INDEX_NOT_FOUND

public static final int INDEX_NOT_FOUND

The index value when an element is not found in a list or array: -1. This value is returned by methods in this class and can also be used in comparisons with values returned by various method from List.

另请参阅:

常量字段值

构造器详细资料

ArrayUtils

public ArrayUtils()

方法详细资料

isNotEmpty

public static <T> boolean isNotEmpty(T[] array)

Checks if an array of Objects is not empty or not null.

类型参数:

T - the component type of the array

参数:

array - the array to test

返回:

true if the array is not empty or not null

从以下版本开始:

2.5

isEmpty

public static <T> boolean isEmpty(T[] array)

Checks if an array of Objects is empty or null.

类型参数:

T - the component type of the array

参数:

array - the array to test

返回:

true if the array is empty or null

从以下版本开始:

2.5

subarray

public static <T> T[] subarray(T[] array,
               int startIndexInclusive,
               int endIndexExclusive)

Produces a new array containing the elements between the start and end indices.

The start index is inclusive, the end index exclusive. Null array input produces null output.

The component type of the subarray is always the same as that of the input array. Thus, if the input is an array of type Date, the following usage is envisaged:

 Date[] someDates = (Date[])ArrayUtils.subarray(allDates, 2, 5);
 

类型参数:

T - the component type of the array

参数:

array - the array

startIndexInclusive - the starting index. Undervalue (<0) is promoted to 0, overvalue (>array.length) results in an empty array.

endIndexExclusive - elements up to endIndex-1 are present in the returned subarray. Undervalue (< startIndex) produces empty array, overvalue (>array.length) is demoted to array length.

返回:

a new array containing the elements between the start and end indices.

从以下版本开始:

2.1

另请参阅:

Arrays.copyOfRange(Object[], int, int)

subarray

public static int[] subarray(int[] array,
             int startIndexInclusive,
             int endIndexExclusive)

Produces a new int array containing the elements between the start and end indices.

The start index is inclusive, the end index exclusive. Null array input produces null output.

参数:

array - the array

startIndexInclusive - the starting index. Undervalue (<0) is promoted to 0, overvalue (>array.length) results in an empty array.

endIndexExclusive - elements up to endIndex-1 are present in the returned subarray. Undervalue (< startIndex) produces empty array, overvalue (>array.length) is demoted to array length.

返回:

a new array containing the elements between the start and end indices.

从以下版本开始:

2.1

另请参阅:

Arrays.copyOfRange(int[], int, int)

getLength

public static int getLength(Object array)

Returns the length of the specified array. This method can deal with Object arrays and with primitive arrays.

If the input array is null, 0 is returned.

 ArrayUtils.getLength(null)            = 0
 ArrayUtils.getLength([])              = 0
 ArrayUtils.getLength([null])          = 1
 ArrayUtils.getLength([true, false])   = 2
 ArrayUtils.getLength([1, 2, 3])       = 3
 ArrayUtils.getLength(["a", "b", "c"]) = 3
 

参数:

array - the array to retrieve the length from, may be null

返回:

The length of the array, or 0 if the array is null

抛出:

IllegalArgumentException - if the object argument is not an array.

从以下版本开始:

2.1

add

public static <T> T[] add(T[] array,
          T element)

Copies the given array and adds the given element at the end of the new array.

The new array contains the same elements of the input array plus the given element in the last position. The component type of the new array is the same as that of the input array.

If the input array is null, a new one element array is returned whose component type is the same as the element, unless the element itself is null, in which case the return type is Object[]

 ArrayUtils.add(null, null)      = [null]
 ArrayUtils.add(null, "a")       = ["a"]
 ArrayUtils.add(["a"], null)     = ["a", null]
 ArrayUtils.add(["a"], "b")      = ["a", "b"]
 ArrayUtils.add(["a", "b"], "c") = ["a", "b", "c"]
 

类型参数:

T - the component type of the array

参数:

array - the array to "add" the element to, may be null

element - the object to add, may be null

返回:

A new array containing the existing elements plus the new element The returned array type will be that of the input array (unless null), in which case it will have the same type as the element. If both are null, an IllegalArgumentException is thrown

抛出:

IllegalArgumentException - if both arguments are null

从以下版本开始:

2.1

add

public static int[] add(int[] array,
        int element)

Copies the given array and adds the given element at the end of the new array.

The new array contains the same elements of the input array plus the given element in the last position. The component type of the new array is the same as that of the input array.

If the input array is null, a new one element array is returned whose component type is the same as the element.

 ArrayUtils.add(null, 0)   = [0]
 ArrayUtils.add([1], 0)    = [1, 0]
 ArrayUtils.add([1, 0], 1) = [1, 0, 1]
 

参数:

array - the array to copy and add the element to, may be null

element - the object to add at the last index of the new array

返回:

A new array containing the existing elements plus the new element

从以下版本开始:

2.1

isSameLength

public static boolean isSameLength(Object[] array1,
                   Object[] array2)

Checks whether two arrays are the same length, treating null arrays as length 0.

Any multi-dimensional aspects of the arrays are ignored.

参数:

array1 - the first array, may be null

array2 - the second array, may be null

返回:

true if length of arrays matches, treating null as an empty array

toString

public static String toString(Object array)

Outputs an array as a String, treating null as an empty array.

Multi-dimensional arrays are handled correctly, including multi-dimensional primitive arrays.

The format is that of Java source code, for example {a,b}.

参数:

array - the array to get a toString for, may be null

返回:

a String representation of the array, '{}' if null array input

contains

public static boolean contains(Object[] array,
               Object objectToFind)

Checks if the object is in the given array.

The method returns false if a null array is passed in.

参数:

array - the array to search through

objectToFind - the object to find

返回:

true if the array contains the object

indexOf

public static int indexOf(Object[] array,
          Object objectToFind)

Finds the index of the given object in the array.

This method returns INDEX_NOT_FOUND (-1) for a null input array.

参数:

array - the array to search through for the object, may be null

objectToFind - the object to find, may be null

返回:

the index of the object within the array, INDEX_NOT_FOUND (-1) if not found or null array input

indexOf

public static int indexOf(Object[] array,
          Object objectToFind,
          int startIndex)

Finds the index of the given object in the array starting at the given index.

This method returns INDEX_NOT_FOUND (-1) for a null input array.

A negative startIndex is treated as zero. A startIndex larger than the array length will return INDEX_NOT_FOUND (-1).

参数:

array - the array to search through for the object, may be null

objectToFind - the object to find, may be null

startIndex - the index to start searching at

返回:

the index of the object within the array starting at the index, INDEX_NOT_FOUND (-1) if not found or null array input