Package org.apache.jackrabbit.oak.commons.collections

Class SetUtils

java.lang.Object

org.apache.jackrabbit.oak.commons.collections.SetUtils

public class SetUtils
extends Object

Utility methods for Set conversions.

Method Summary

Modifier and Type	Method	Description
static <T> Set<T>	difference(Set<T> s1, Set<T> s2)	Returns a new set containing the difference of the two specified sets.
static <T> @NotNull Set<T>	intersection(@NotNull Set<T> s1, @NotNull Set<T> s2)	Returns a new set containing the intersection of the two specified sets.
static <K> @NotNull Set<K>	newConcurrentHashSet()	Creates a new, empty Set which is backed by ConcurrentHashMap to allow concurrent access.
static <K> @NotNull Set<K>	newConcurrentHashSet(@NotNull Iterable<? extends K> elements)	Creates a new Set with given values which is backed by ConcurrentHashMap to allow concurrent access.
static <K> @NotNull Set<K>	newHashSet(int capacity)	Creates a new, empty HashSet with expected capacity.
static <E> @NotNull Set<E>	newIdentityHashSet()	Creates a new, empty IdentityHashSet with default size.
static <K> @NotNull Set<K>	newLinkedHashSet(int capacity)	Creates a new, empty LinkedHashSet with expected capacity.
static <T> Set<T>	symmetricDifference(Set<T> s1, Set<T> s2)	Returns a new set containing the symmetric difference of the two specified sets.
static <T> @NotNull Set<T>	toLinkedSet(@NotNull Iterable<? extends T> iterable)	Convert an iterable to a LinkedHashSet.
static <T> @NotNull Set<T>	toLinkedSet(@NotNull T... elements)	Convert a vararg list of items to a set.
static <T> @NotNull Set<T>	toSet(@NotNull Iterable<? extends T> iterable)	Convert an iterable to a set.
static <T> @NotNull Set<T>	toSet(@NotNull Iterator<T> iterator)	Convert an iterator to a set.
static <T> @NotNull Set<T>	toSet(@NotNull T... elements)	Convert a vararg list of items to a set.
static <T extends Comparable> @NotNull TreeSet<T>	toTreeSet(@NotNull Iterable<? extends T> iterable)	Convert an iterable to a TreeSet.
static <T> @NotNull Set<T>	union(@NotNull Set<T> s1, @NotNull Set<T> s2)	Returns a new set containing the union of the two specified sets.

Methods inherited from class java.lang.Object

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

Method Detail

toSet

@NotNull
public static <T> @NotNull Set<T> toSet(@NotNull
                                        @NotNull Iterable<? extends T> iterable)

Convert an iterable to a set. The returning set is mutable and supports all optional operations.

Type Parameters:

T - the type of the elements

Parameters:

iterable - the iterable to convert

Returns:

the set

toSet

@NotNull
public static <T> @NotNull Set<T> toSet(@NotNull
                                        @NotNull Iterator<T> iterator)

Convert an iterator to a set. The returning set is mutable and supports all optional operations.

Type Parameters:

T - the type of the elements

Parameters:

iterator - the iterator to convert

Returns:

the set

toSet

@SafeVarargs
@NotNull
public static <T> @NotNull Set<T> toSet(@NotNull
                                        @NotNull T... elements)

Convert a vararg list of items to a set. The returning set is mutable and supports all optional operations.

Type Parameters:

T - the type of the elements

Parameters:

elements - elements to convert

Returns:

the set

newHashSet

@NotNull
public static <K> @NotNull Set<K> newHashSet(int capacity)

Creates a new, empty HashSet with expected capacity.

The returned set is large enough to add expected no. of elements without resizing.

Parameters:

capacity - the expected number of elements

Throws:

IllegalArgumentException - if capacity is negative

See Also:

MapUtils.newHashMap(int), newLinkedHashSet(int)

newIdentityHashSet

@NotNull
public static <E> @NotNull Set<E> newIdentityHashSet()

Creates a new, empty IdentityHashSet with default size.

toLinkedSet

@NotNull
public static <T> @NotNull Set<T> toLinkedSet(@NotNull
                                              @NotNull Iterable<? extends T> iterable)

Convert an iterable to a LinkedHashSet. The returning set is mutable and supports all optional operations.

Type Parameters:

T - the type of the elements

Parameters:

iterable - the iterable to convert

Returns:

the linkedHashSet

toLinkedSet

@SafeVarargs
@NotNull
public static <T> @NotNull Set<T> toLinkedSet(@NotNull
                                              @NotNull T... elements)

Convert a vararg list of items to a set. The returning set is mutable and supports all optional operations.

Type Parameters:

T - the type of the elements

Parameters:

elements - elements to convert

Returns:

the set

newLinkedHashSet

@NotNull
public static <K> @NotNull Set<K> newLinkedHashSet(int capacity)

Creates a new, empty LinkedHashSet with expected capacity.

The returned set is large enough to add expected no. of elements without resizing.

Parameters:

capacity - the expected number of elements

Throws:

IllegalArgumentException - if capacity is negative

See Also:

MapUtils.newHashMap(int), newHashSet(int)

toTreeSet

@NotNull
public static <T extends Comparable> @NotNull TreeSet<T> toTreeSet(@NotNull
                                                                   @NotNull Iterable<? extends T> iterable)

Convert an iterable to a TreeSet. The returning set is mutable and supports all optional operations.

Type Parameters:

T - the type of the elements

Parameters:

iterable - the iterable to convert

Returns:

the treeSet

Throws:

ClassCastException - if the specified object cannot be compared with the elements currently in this set

NullPointerException - if the specified element is null and this set uses natural ordering, or its comparator does not permit null elements

newConcurrentHashSet

@NotNull
public static <K> @NotNull Set<K> newConcurrentHashSet()

Creates a new, empty Set which is backed by ConcurrentHashMap to allow concurrent access. Returning Set doesn't allow null keys and values.

Returns:

a new, empty Set which is backed by ConcurrentHashMap.

See Also:

MapUtils.newHashMap(int), newLinkedHashSet(int), (int)

newConcurrentHashSet

@NotNull
public static <K> @NotNull Set<K> newConcurrentHashSet(@NotNull
                                                       @NotNull Iterable<? extends K> elements)

Creates a new Set with given values which is backed by ConcurrentHashMap to allow concurrent access. Returning Set doesn't allow null keys and values.

Returns:

a new, empty Set which is backed by ConcurrentHashMap.

Throws:

NullPointerException - if any element of the iterable is null

See Also:

MapUtils.newHashMap(int), newLinkedHashSet(int), newConcurrentHashSet()

union

@NotNull
public static <T> @NotNull Set<T> union(@NotNull
                                        @NotNull Set<T> s1,
                                        @NotNull
                                        @NotNull Set<T> s2)

Returns a new set containing the union of the two specified sets. The union of two sets is a set containing all the elements of both sets.

Type Parameters:

T - the type of elements in the sets

Parameters:

s1 - the first set, must not be null

s2 - the second set, must not be null

Returns:

a new set containing the union of the two specified sets

Throws:

NullPointerException - if either of the sets is null

intersection

@NotNull
public static <T> @NotNull Set<T> intersection(@NotNull
                                               @NotNull Set<T> s1,
                                               @NotNull
                                               @NotNull Set<T> s2)

Returns a new set containing the intersection of the two specified sets. The intersection of two sets is a set containing only the elements that are present in both sets.

Type Parameters:

T - the type of elements in the sets

Parameters:

s1 - the first set, must not be null

s2 - the second set, must not be null

Returns:

a new set containing the intersection of the two specified sets

Throws:

NullPointerException - if either of the sets is null

symmetricDifference

public static <T> Set<T> symmetricDifference(Set<T> s1,
                                             Set<T> s2)

Returns a new set containing the symmetric difference of the two specified sets. The symmetric difference of two sets is a set containing elements that are in either of the sets, but not in their intersection.

Type Parameters:

T - the type of elements in the sets

Parameters:

s1 - the first set, must not be null

s2 - the second set, must not be null

Returns:

a new set containing the symmetric difference of the two specified sets

Throws:

NullPointerException - if either of the sets is null

difference

public static <T> Set<T> difference(Set<T> s1,
                                    Set<T> s2)

Returns a new set containing the difference of the two specified sets. The difference of two sets is a set containing elements that are in the first set but not in the second set.

Type Parameters:

T - the type of elements in the sets

Parameters:

s1 - the first set, must not be null

s2 - the second set, must not be null

Returns:

a new set containing the difference of the two specified sets

Throws:

NullPointerException - if either of the sets is null