Package org.drasyl.util

Class SetUtil

java.lang.Object

org.drasyl.util.SetUtil

public final class SetUtil
extends Object

Utility class for operations on Sets.

Method Summary

Modifier and Type	Method	Description
static <A,B> Set<Pair<A,B>>	cartesianProduct(Set<A> a, Set<B> b)	Returns the cartesian product of the two sets a and b.
static <E> Set<E>	difference(Set<E> a, E... b)	Returns a set containing all elements from set a that are not b.
static <E> Set<E>	difference(Set<E> a, Collection<E> b)	Returns a set containing all elements from set a that are not in set b.
static <E> E	firstElement(Set<E> set)	Returns the first element from set set.
static <E> Set<E>	merge(Set<E> a, E... b)	Returns a set containing all elements from a and the element b.
static <E> Set<E>	merge(Set<E> a, Set<E> b)	Returns a set containing all elements from set a and set b.
static <E> E	nthElement(Set<E> set, int n)	Returns the n-th element from set set.

Methods inherited from class java.lang.Object

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

Method Detail

merge

public static <E> Set<E> merge(Set<E> a,
                               Set<E> b)

Returns a set containing all elements from set a and set b. If there are duplicates in both sets, the elements from the set a are favored.

Type Parameters:

E - the Set's element type

Parameters:

a - set a

b - set b

Returns:

a Set containing the specified elements

merge

@SafeVarargs
public static <E> Set<E> merge(Set<E> a,
                               E... b)

Returns a set containing all elements from a and the element b. b is ignored if an equal element is already contained in the set a.

Type Parameters:

E - the Set's element type

Parameters:

a - set a

b - set b

Returns:

a Set containing the specified elements

difference

public static <E> Set<E> difference(Set<E> a,
                                    Collection<E> b)

Returns a set containing all elements from set a that are not in set b.

Type Parameters:

E - the Set's element type

Parameters:

a - set a

b - set b

Returns:

a Set containing the specified elements

difference

@SafeVarargs
public static <E> Set<E> difference(Set<E> a,
                                    E... b)

Returns a set containing all elements from set a that are not b.

Type Parameters:

E - the Set's element type

Parameters:

a - set a

b - set b

Returns:

a Set containing the specified elements

nthElement

public static <E> E nthElement(Set<E> set,
                               int n)

Returns the n-th element from set set. Throws a IndexOutOfBoundsException if n is negative or greater than the set's cardinality.

Type Parameters:

E - the Set's element type

Parameters:

set - a set

n - specifies the element to be taken

Returns:

n-th element from set set

Throws:

IndexOutOfBoundsException - if n is negative or greater than the set's cardinality

firstElement

public static <E> E firstElement(Set<E> set)

Returns the first element from set set. Returns null if set is empty.

Type Parameters:

E - the Set's element type

Parameters:

set - a set

Returns:

first element from set set

cartesianProduct

public static <A,B> Set<Pair<A,B>> cartesianProduct(Set<A> a,
                                                                Set<B> b)

Returns the cartesian product of the two sets a and b. This is the set of all ordered Pairs (x,y) where x is in a and y is in b.

Type Parameters:

A - the type of the elements in set a

B - the type of the elements in set b

Parameters:

a - first set for the cartesian product

b - second set for the cartesian product

Returns:

the cartesian product of the two sets a and b