cn.ponfee.commons.collect

类 Collects

java.lang.Object

cn.ponfee.commons.collect.Collects

public final class Collects
extends Object

集合工具类

作者:

Ponfee

构造器概要

构造器

构造器和说明
Collects()

方法概要

限定符和类型	方法和说明
static <A,B,T> List<List<T>>	cartesian(List<A> x, List<B> y, BiFunction<A,B,T> fun) Compute cartesian product [1, 2, 3] x [4, 5, 6] = [[4, 5, 6], [8, 10, 12], [12, 15, 18]]
static <T> T[]	concat(IntFunction<T[]> generator, T[]... arrays) Returns a new array for merged the generic array generator
static <T> List<T>	concat(List<T> list, T... array)
static <E,R> List<R>	convert(Collection<E> collection, Function<E,R> mapper)
static <E,R> List<R>	convert(Collection<E> collection, Predicate<? super E> predicate, Function<E,R> mapper)
static <T> List<T>	different(List<T> list1, List<T> list2) list差集 different([1,2,3], [2,3,4]) = [1,4]
static <K,V> Map<K,V>	different(Map<K,V> map1, Map<K,V> map2) map差集
static <T> Set<T>	different(Set<T> set1, Set<T> set2) The two set different elements
static <T> List<T>	duplicate(Collection<T> list)
static <T,R> List<R>	duplicate(Collection<T> list, Function<T,R> mapper) Returns the duplicates elements for list
static <T> void	expand(List<T> list, int size, Supplier<T> supplier) Expand the list size
static <T> T	get(List<T> list, int index)
static <T> T	get(T[] array, int index)
static <T> T	getFirst(Collection<T> values) Gets the first element for values
static <T> T	getLast(Collection<T> values) Gets the last element for values
static <T> List<T>	intersect(Collection<T> coll1, Collection<T> coll2) two Collection intersect intersect([1,2,3], [2,3,4]) = [2,3]
static <T> T[]	intersect(T[] array1, T[] array2) two array intersect
static <T> T[]	newArray(Class<? extends T[]> newType, int length)
static <E> LinkedList<E>	newLinkedList(E element)
static List<int[]>	partition(int[] array, int size) Returns consecutive sub array of an array, each of the same size (the final list may be smaller).
static <T> List<T>	requireNonEmpty(List<T> list) Checks that the specified list reference is not null and not empty, throws a customized IllegalStateException if it is.
static <T> T[]	requireNonEmpty(T[] array) Checks that the specified array reference is not null and not empty, throws a customized IllegalStateException if it is.
static List<Object[]>	rotate(List<Object[]> list) Rotate list array data [[a,b,c,d],[1,2,3,4]] -> [[a,1],[b,2],[c,3],[d,4]]
static <T> void	set(List<T> list, int index, T obj) Puts the element to list specified index
static int[]	sortAndGetIndexSwapMapping(int[] array)
static <E> Stream<E>	stream(Collection<E> collection)
static <T> T[]	toArray(T... args) 转数组
static List<Object>	toList(Object obj) object to list
static <T> List<T>	union(Collection<T> coll1, Collection<T> coll2) two Collection union result

从类继承的方法 java.lang.Object

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

构造器详细资料

Collects

public Collects()

方法详细资料

toArray

public static <T> T[] toArray(T... args)

转数组

参数:

args -

返回:

toList

public static List<Object> toList(Object obj)

object to list

参数:

obj - of elements

返回:

list with the same elements

newLinkedList

public static <E> LinkedList<E> newLinkedList(E element)

getFirst

public static <T> T getFirst(Collection<T> values)

Gets the first element for values

类型参数:

T - the values element type

参数:

values - the values

返回:

first element of values

getLast

public static <T> T getLast(Collection<T> values)

Gets the last element for values

类型参数:

T - the values element type

参数:

values - the values

返回:

last element of values

get

public static <T> T get(T[] array,
                        int index)

get

public static <T> T get(List<T> list,
                        int index)

intersect

public static <T> List<T> intersect(Collection<T> coll1,
                                    Collection<T> coll2)

two Collection intersect intersect([1,2,3], [2,3,4]) = [2,3]

参数:

coll1 - the collection 1

coll2 - the collection 2

返回:

a list of the two collection intersect result

intersect

public static <T> T[] intersect(T[] array1,
                                T[] array2)

two array intersect

参数:

array1 -

array2 -

返回:

union

public static <T> List<T> union(Collection<T> coll1,
                                Collection<T> coll2)

two Collection union result

参数:

coll1 -

coll2 -

返回:

different

public static <T> List<T> different(List<T> list1,
                                    List<T> list2)

list差集 different([1,2,3], [2,3,4]) = [1,4]

参数:

list1 -

list2 -

返回:

different

public static <T> Set<T> different(Set<T> set1,
                                   Set<T> set2)

The two set different elements

参数:

set1 -

set2 -

返回:

different

public static <K,V> Map<K,V> different(Map<K,V> map1,
                                       Map<K,V> map2)

map差集

参数:

map1 -

map2 -

返回:

duplicate

public static <T> List<T> duplicate(Collection<T> list)

duplicate

public static <T,R> List<R> duplicate(Collection<T> list,
                                      Function<T,R> mapper)

Returns the duplicates elements for list

参数:

list - the list

返回:

a set of duplicates elements for list

concat

public static <T> T[] concat(IntFunction<T[]> generator,
                             T[]... arrays)

Returns a new array for merged the generic array generator

参数:

generator - the generic array generator

arrays - the multiple generic object array

返回:

a new array of merged

另请参阅:

org.apache.commons.lang3.ArrayUtils#addAll(T[] array1, T... array2)

set

public static <T> void set(List<T> list,
                           int index,
                           T obj)

Puts the element to list specified index

参数:

list - a list

index - spec index

obj - the element

expand

public static <T> void expand(List<T> list,
                              int size,
                              Supplier<T> supplier)

Expand the list size

类型参数:

T - the element type

参数:

list - the list

size - the target size

supplier - element provider

partition

public static List<int[]> partition(int[] array,
                                    int size)

Returns consecutive sub array of an array, each of the same size (the final list may be smaller).

  Collects.partition(new int[]{1,1,2,5,3}, 1)    ->  [1, 1, 2, 5, 3]
  Collects.partition(new int[]{1,1,2,5,3}, 3)    ->  [1, 1]; [2, 5]; [3]
  Collects.partition(new int[]{1,1,2,5,3}, 5)    ->  [1]; [1]; [2]; [5]; [3]
  Collects.partition(new int[]{1,1,2,5,3}, 6)    ->  [1]; [1]; [2]; [5]; [3]
  Collects.partition(new int[]{1,1,2,5,3}, 100)  ->  [1]; [1]; [2]; [5]; [3]
 

参数:

array - the array

size - the size

返回:

a list of consecutive sub sets

cartesian

public static <A,B,T> List<List<T>> cartesian(List<A> x,
                                              List<B> y,
                                              BiFunction<A,B,T> fun)

Compute cartesian product [1, 2, 3] x [4, 5, 6] = [[4, 5, 6], [8, 10, 12], [12, 15, 18]]

参数:

x - the list of type A

y - the list of type B

fun - convert A and B to T

返回:

a list of type T

rotate

public static List<Object[]> rotate(List<Object[]> list)

Rotate list array data [[a,b,c,d],[1,2,3,4]] -> [[a,1],[b,2],[c,3],[d,4]]

参数:

list - the list

返回:

a list array result

sortAndGetIndexSwapMapping

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

requireNonEmpty

public static <T> T[] requireNonEmpty(T[] array)

Checks that the specified array reference is not null and not empty, throws a customized IllegalStateException if it is.

类型参数:

T - the type of the array element

参数:

array - the array

返回:

array if not null and not empty

requireNonEmpty

public static <T> List<T> requireNonEmpty(List<T> list)

Checks that the specified list reference is not null and not empty, throws a customized IllegalStateException if it is.

类型参数:

T - the type of the list element

参数:

list - the list

返回:

list if not null and not empty

convert

public static <E,R> List<R> convert(Collection<E> collection,
                                    Function<E,R> mapper)

convert

public static <E,R> List<R> convert(Collection<E> collection,
                                    Predicate<? super E> predicate,
                                    Function<E,R> mapper)

concat

@SafeVarargs
public static <T> List<T> concat(List<T> list,
                                              T... array)

newArray

public static <T> T[] newArray(Class<? extends T[]> newType,
                               int length)

stream

public static <E> Stream<E> stream(Collection<E> collection)