org.lockss.util

Class CollectionUtil2

java.lang.Object

org.lockss.util.CollectionUtil2

public class CollectionUtil2
extends Object

Collection utilities.

Since:

1.1.0

Constructor Summary

Constructors

Constructor and Description
CollectionUtil2()

Method Summary

Modifier and Type	Method and Description
protected static <T,C extends Collection<T>> C	collection(Supplier<C> funcEmptyCollection, T... elements) Creates a new collection from any number of arguments.
protected static <C extends Collection<String>> C	fromCsvStringTokenizer(Supplier<C> funcEmptyCollection, String csv) Creates a collection containing the elements of a comma separated string, with the caveat that the processing is done by StringTokenizer with the delimiter ",".
protected static <T,C extends Collection<T>> C	fromIterable(Supplier<C> funcEmptyCollection, Iterable<T> iterable) Creates a collection containing the elements of the given iterable.
protected static <T,C extends Collection<T>> C	fromIterator(Supplier<C> funcEmptyCollection, Iterator<T> iterator) Creates a collection containing the elements of the given iterator.
protected static <T,C extends Collection<T>> C	immutableCollectionOfType(IntFunction<C> funcEmptyCollectionOfSize, UnaryOperator<C> funcImmutableCollection, Collection<?> coll, Class<T> type, boolean nullOk) Checks that all elements of the collection are of the specified type, and returns an unmodifiable copy of the collection, with null elements either allowed or disallowed.

Methods inherited from class java.lang.Object

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

Constructor Detail

CollectionUtil2

public CollectionUtil2()

Method Detail

collection

protected static <T,C extends Collection<T>> C collection(Supplier<C> funcEmptyCollection,
                                                          T... elements)

Creates a new collection from any number of arguments.

Type Parameters:

T - The type of element contained in the collection.

C - The type of collection.

Parameters:

funcEmptyCollection - A Supplier functor returning a brand new collection.

elements - A succession of elements (possibly zero).

Returns:

A collection of those elements (an empty collection if no elements).

immutableCollectionOfType

protected static <T,C extends Collection<T>> C immutableCollectionOfType(IntFunction<C> funcEmptyCollectionOfSize,
                                                                         UnaryOperator<C> funcImmutableCollection,
                                                                         Collection<?> coll,
                                                                         Class<T> type,
                                                                         boolean nullOk)

Checks that all elements of the collection are of the specified type, and returns an unmodifiable copy of the collection, with null elements either allowed or disallowed.

Type Parameters:

T - The type of element contained in the collection.

C - The type of collection.

Parameters:

funcEmptyCollectionOfSize - An IntFunction functor that accepts a size and produces an empty collection on that size (e.g. ArrayList.ArrayList(int), HashSet.HashSet(int)).

funcImmutableCollection - A UnaryOperator functor that accepts a collection and returns an unmodifiable view of it (e.g. Collections.unmodifiableList(List), Collections.unmodifiableSet(Set)).

coll - The input collection.

type - The class with which all items of the collection must be assignment-compatible.

nullOk - Whether null elements are allowed.

Returns:

An immutable copy of the collection.

Throws:

NullPointerException - if the collection is null or if any element is null.

ClassCastException - if an item is not of the proper type.

Since:

1.1.0

fromIterator

protected static <T,C extends Collection<T>> C fromIterator(Supplier<C> funcEmptyCollection,
                                                            Iterator<T> iterator)

Creates a collection containing the elements of the given iterator.

Type Parameters:

T - The type of element contained in the collection.

C - The type of collection.

Parameters:

funcEmptyCollection - A Supplier functor returning a brand new collection.

iterator - An iterator.

Returns:

A collection built from consuming the iterator.

Since:

1.1.0

fromIterable

protected static <T,C extends Collection<T>> C fromIterable(Supplier<C> funcEmptyCollection,
                                                            Iterable<T> iterable)

Creates a collection containing the elements of the given iterable.

Type Parameters:

T - The type of element contained in the collection.

C - The type of collection.

Parameters:

funcEmptyCollection - A Supplier functor returning a brand new collection.

iterable - An iterable.

Returns:

A collection built from consuming the iterable.

Since:

1.1.0

fromCsvStringTokenizer

protected static <C extends Collection<String>> C fromCsvStringTokenizer(Supplier<C> funcEmptyCollection,
                                                                         String csv)

Creates a collection containing the elements of a comma separated string, with the caveat that the processing is done by StringTokenizer with the delimiter ",".

StringTokenizer simplistically looks for separators without a quoting mechanism to return tokens containing the delimiter, nor does it trim whitespace between tokens and delimiters. It also does not return empty tokens, so calling this method with ",,," will return an empty collection, not a collection of four empty strings.

Type Parameters:

C - The type of collection.

Parameters:

funcEmptyCollection - A Supplier functor that generates an empty collection.

csv - A simplistic CSV string.

Returns:

A collection of tokens as separated by commas in the given input string.

Since:

1.1.0

See Also:

fromCsvStringTokenizer(Supplier, String)