org.lockss.util

Class SetUtil

java.lang.Object

org.lockss.util.SetUtil

public class SetUtil
extends Object

Set utilities.

Since:

1.1.0

Method Summary

Modifier and Type	Method and Description
static <T> Set<T>	fromArray(T[] array) Deprecated. Use set(Object...) instead.
static Set<String>	fromCSV(String csv) Creates a set containing the elements of a comma separated string, with the caveat that the processing is done by StringTokenizer with the delimiter ",".
static <T> Set<T>	fromIterable(Iterable<T> iterable) Creates a set containing the elements of the given iterable.
static <T> Set<T>	fromIterator(Iterator<T> iterator) Creates a set containing the elements of the given iterator.
static <T> Set<T>	fromList(List<T> list) Create a set containing the elements of the given list.
static <T> Set<T>	immutableSetOfType(Set<?> set, Class<T> type) Checks that all elements of the set are of the specified type, and returns an unmodifiable copy of the set, with null elements disallowed.
static <T> Set<T>	immutableSetOfTypeOrNull(Set<?> set, Class<T> type) Checks that all elements of the set are of the specified type, and returns an unmodifiable copy of the set, with null elements allowed.
static <T> Set<T>	set(T... elements) Creates a modifiable set from any number of arguments.
static <T> Set<T>	theSet(Collection<T> coll) Create a set containing the elements of the given collection.

Methods inherited from class java.lang.Object

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

Method Detail

set

public static <T> Set<T> set(T... elements)

Creates a modifiable set from any number of arguments.

Type Parameters:

T - The type of element contained in the set.

Parameters:

elements - A succession of elements (possibly zero).

Returns:

A modifiable Set of those elements (an empty set if no elements).

Since:

1.1.0

See Also:

CollectionUtil2.collection(Supplier, Object...)

immutableSetOfType

public static <T> Set<T> immutableSetOfType(Set<?> set,
                                            Class<T> type)

Checks that all elements of the set are of the specified type, and returns an unmodifiable copy of the set, with null elements disallowed.

Type Parameters:

T - The type of element contained in the set.

Parameters:

set - The input set.

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

Throws:

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

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

Since:

1.1.0

See Also:

immutableSetOfType(Set, Class, boolean)

immutableSetOfTypeOrNull

public static <T> Set<T> immutableSetOfTypeOrNull(Set<?> set,
                                                  Class<T> type)

Checks that all elements of the set are of the specified type, and returns an unmodifiable copy of the set, with null elements allowed.

Type Parameters:

T - The type of element contained in the set.

Parameters:

set - The input set.

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

Throws:

NullPointerException - if the set is null

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

Since:

1.1.0

See Also:

immutableSetOfType(Set, Class, boolean)

fromArray

@Deprecated
public static <T> Set<T> fromArray(T[] array)

Deprecated. Use set(Object...) instead.

Now that set(Object...) is generic, this method does exactly the same thing and simply calls it.

Type Parameters:

T - The type of element contained in the set.

Parameters:

array - An array of objects.

Returns:

A modifiable Set made of the objects in the array.

Since:

1.1.0

See Also:

set(Object...)

theSet

public static <T> Set<T> theSet(Collection<T> coll)

Create a set containing the elements of the given collection.

Type Parameters:

T - The type of element contained in the set.

Parameters:

coll - A collection.

Returns:

A set made from the elements of the given collection.

Since:

1.1.0

See Also:

HashSet.HashSet(Collection)

fromList

public static <T> Set<T> fromList(List<T> list)

Create a set containing the elements of the given list.

Type Parameters:

T - The type of element contained in the set.

Parameters:

list - A list.

Returns:

A set made from the elements of the given list.

Since:

1.1.0

See Also:

theSet(Collection)

fromIterator

public static <T> Set<T> fromIterator(Iterator<T> iterator)

Creates a set containing the elements of the given iterator.

Type Parameters:

T - The type of element contained in the set.

Parameters:

iterator - An iterator.

Returns:

A set built from consuming the iterator.

Since:

1.1.0

See Also:

CollectionUtil2.fromIterator(Supplier, Iterator)

fromIterable

public static <T> Set<T> fromIterable(Iterable<T> iterable)

Creates a set containing the elements of the given iterable.

Type Parameters:

T - The type of element contained in the set.

Parameters:

iterable - An iterable.

Returns:

A set built from the elements in the iterable.

Since:

1.1.0

See Also:

CollectionUtil2.fromIterable(Supplier, Iterable)

fromCSV

public static Set<String> fromCSV(String csv)

Creates a set 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 set, not a set of four empty strings.

Parameters:

csv - A simplistic CSV string.

Returns:

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

Since:

1.1.0

See Also:

CollectionUtil2.fromCsvStringTokenizer(Supplier, String)