net.openhft.chronicle.testframework

Class Permutation

java.lang.Object

net.openhft.chronicle.testframework.Permutation

public final class Permutation
extends Object

General Permutation support from http://minborgsjavapot.blogspot.com/2015/07/java-8-master-permutations.html

Author:

Per Minborg

Method Summary

Modifier and Type	Method and Description
static long	factorial(int n) Returns the factorial (n!) for the given n value.
static <T> Stream<List<T>>	of(@NotNull Collection<T> items) Creates and returns a Stream of all permutations of the provided items list.
static <T> Stream<List<T>>	of(@NotNull Stream<T> items) Creates and returns a Stream of all permutations of the provided items list.
static <T> Stream<List<T>>	of(T... items) Creates and returns a Stream of all permutations of the provided items array.
static <T> List<T>	permutation(long no, @NotNull List<T> items) Returns the given no (of n!) permutation variant of the given items.

Methods inherited from class java.lang.Object

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

Method Detail

factorial

public static long factorial(int n)

Returns the factorial (n!) for the given n value.

Parameters:

n - parameter

Returns:

the factorial (n!) for the given n value

permutation

public static <T> List<T> permutation(long no,
                                      @NotNull
                                      @NotNull List<T> items)

Returns the given no (of n!) permutation variant of the given items.

Note that the number of permutations increases very rapidly as the length of the provided items array increases.

Type Parameters:

T - type of the elements

Parameters:

no - index to get permutations for

items - to create permutations for

Returns:

the given no (of n!) permutation variant of the given items

of

@SafeVarargs
public static <T> Stream<List<T>> of(@NotNull
                                                  T... items)

Creates and returns a Stream of all permutations of the provided items array.

Note that the number of permutations increases very rapidly as the length of the provided items array increases.

Type Parameters:

T - type of the elements

Parameters:

items - to create permutations for

Returns:

a Stream of all permutations of the provided items array

Throws:

NullPointerException - if the provided items array is null.

of

public static <T> Stream<List<T>> of(@NotNull
                                     @NotNull Collection<T> items)

Creates and returns a Stream of all permutations of the provided items list.

Note that the number of permutations increases very rapidly as the length of the provided items list increases.

Type Parameters:

T - type of the elements

Parameters:

items - to create permutations for

Returns:

a Stream of all permutations of the provided items list

Throws:

NullPointerException - if the provided items list is null.

of

public static <T> Stream<List<T>> of(@NotNull
                                     @NotNull Stream<T> items)

Creates and returns a Stream of all permutations of the provided items list.

Note that the number of permutations increases very rapidly as the length of the provided items list increases.

It is unspecified if the method lazily consume the provided stream before providing the result or not.

Type Parameters:

T - type of the elements

Parameters:

items - to create permutations for

Returns:

a Stream of all permutations of the provided items list

Throws:

NullPointerException - if the provided items stream is null.