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 stream.
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) Generates a stream of all possible permutations for 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)

Generates a stream of all possible permutations for the given items.

This method is an overload of of(Collection) that accepts an array instead of a collection.

Type Parameters:

T - Type of the elements

Parameters:

items - Array of items to create permutations for

Returns:

Stream containing all permutations of the given items

Throws:

NullPointerException - if items is null

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.

This method generates a stream that contains all possible arrangements of the elements within the provided items list.

Note that the number of permutations increases very rapidly as the length of the provided items list increases, so use with caution with large lists.

Type Parameters:

T - Type of the elements

Parameters:

items - List of items to create permutations for

Returns:

a Stream containing all permutations of the provided items list

Throws:

NullPointerException - if the provided items list is null

IllegalArgumentException - if the provided permutation number is negative

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 stream.

This method generates a stream that contains all possible arrangements of the elements within the provided items stream.

Note that the number of permutations increases very rapidly as the length of the provided items stream increases, so use with caution with large streams.

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

Type Parameters:

T - Type of the elements

Parameters:

items - Stream of items to create permutations for; must not be null

Returns:

a Stream containing all permutations of the provided items stream

Throws:

NullPointerException - if the provided items stream is null