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

Class CollectionUtils

java.lang.Object

org.apache.jackrabbit.oak.commons.collections.CollectionUtils

public class CollectionUtils
extends Object

Utility methods for collections conversions.

Method Summary

Modifier and Type	Method	Description
static <K,V> @NotNull Map<K,V>	newHashMap(int capacity)	Creates a new, empty HashMap with expected capacity.
static <K> @NotNull Set<K>	newHashSet(int capacity)	Creates a new, empty HashSet with expected capacity.
static <K> @NotNull Set<K>	newLinkedHashSet(int capacity)	Creates a new, empty LinkedHashSet with expected capacity.
static <T> @NotNull Iterable<T>	toIterable(@NotNull Iterator<T> iterator)	Convert an Iterator to an Iterable.
static <T> @NotNull Set<T>	toLinkedSet(@NotNull Iterable<T> iterable)	Convert an iterable to a LinkedHashSet.
static <T> @NotNull List<T>	toList(@NotNull Iterable<T> iterable)	Convert an iterable to a list.
static <T> @NotNull List<T>	toList(Iterator<T> iterator)	Convert an iterator to a list.
static <T> @NotNull Set<T>	toSet(@NotNull Iterable<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> @NotNull Stream<T>	toStream(@NotNull Iterable<T> iterable)	Generates a (non-parallel) Stream for the Iterable
static <T> @NotNull Stream<T>	toStream(@NotNull Iterator<T> iterator)	Generates a (non-parallel) Stream for the Iterable
static <T extends Comparable> @NotNull TreeSet<T>	toTreeSet(@NotNull Iterable<? extends T> iterable)	Convert an iterable to a TreeSet.

Methods inherited from class java.lang.Object

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

Method Detail

toList

@NotNull
public static <T> @NotNull List<T> toList(@NotNull
                                          @NotNull Iterable<T> iterable)

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

Type Parameters:

T - the type of the elements

Parameters:

iterable - the iterable to convert

Returns:

the list

toList

@NotNull
public static <T> @NotNull List<T> toList(Iterator<T> iterator)

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

Type Parameters:

T - the type of the elements

Parameters:

iterator - the iterator to convert

Returns:

the list

toSet

@NotNull
public static <T> @NotNull Set<T> toSet(@NotNull
                                        @NotNull Iterable<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

toLinkedSet

@NotNull
public static <T> @NotNull Set<T> toLinkedSet(@NotNull
                                              @NotNull Iterable<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

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

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:

newHashMap(int), newLinkedHashSet(int)

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:

newHashMap(int), newHashSet(int)

newHashMap

@NotNull
public static <K,V> @NotNull Map<K,V> newHashMap(int capacity)

Creates a new, empty HashMap with expected capacity.

The returned map uses the default load factor of 0.75, and its capacity is large enough to add expected number of elements without resizing.

Parameters:

capacity - the expected number of elements

Throws:

IllegalArgumentException - if capacity is negative

See Also:

newHashSet(int), newLinkedHashSet(int)

toIterable

@NotNull
public static <T> @NotNull Iterable<T> toIterable(@NotNull
                                                  @NotNull Iterator<T> iterator)

Convert an Iterator to an Iterable.

This method is not thread-safe

Parameters:

iterator - iterator to convert

Returns:

a single-use iterable for the iterator (representing the remaining elements in the iterator)

Throws:

IllegalStateException - when Iterable.iterator() is called more than once

toStream

@NotNull
public static <T> @NotNull Stream<T> toStream(@NotNull
                                              @NotNull Iterable<T> iterable)

Generates a (non-parallel) Stream for the Iterable

Parameters:

iterable - iterable to convert

Returns:

the stream

toStream

@NotNull
public static <T> @NotNull Stream<T> toStream(@NotNull
                                              @NotNull Iterator<T> iterator)

Generates a (non-parallel) Stream for the Iterable

This method is not thread-safe

Parameters:

iterator - iterator to convert

Returns:

the stream (representing the remaining elements in the iterator)