An iterable collection of elements of finite Iterable.size
, with
a well-defined notion of value equality.
Collection
is the abstract supertype of List
, Map
,
and Set
.
A Collection
forms a Category
of its elements, and is
Iterable
. The elements of a collection are not
necessarily distinct when compared using Object.equals()
.
A Collection
may be cloned. If a collection is
immutable, it is acceptable that clone()
produce a
reference to the collection itself. If a collection is
mutable, clone()
should produce a collection containing
references to the same elements, with the same structure as
the original collection—that is, it should produce a
shallow copy of the collection.
All Collection
s are required to support a well-defined
notion of value equality, but the
definition of equality depends upon the kind of collection.
Equality for Map
s and Set
s has a quite different
definition to equality for List
s. Instances of two
different kinds of collection are never equal—for
example, a Map
is never equal to a List
.
no type hierarchy
Attributes | |
empty | Source Codeshared actual default Boolean empty Determine if the collection is empty, that is, if it has no elements. Refines Iterable.empty |
permutations | Source Codeshared {[Element+]*} permutations The permutations of this collection, as a stream of nonempty sequences. That is, a stream producing every distinct ordering of the elements of this collection. For example, "ABC".permutations.map(String) is the stream of strings
If this collection is empty, the resulting stream is empty. The permutations are enumerated lexicographically according to the order in which each distinct element of this collection is first produced by its iterator. No permutation is repeated. Two elements are considered distinct if either:
Since 1.2.0 |
string | Source Codeshared actual default String string A string of form |
Inherited Attributes |
Attributes inherited from: Object |
Attributes inherited from: Iterable<Element,Absent> |
Methods | |
clone | Source Codeshared formal Collection<Element> clone() A shallow copy of this collection, that is, a collection with identical elements which does not change if this collection changes. If this collection is immutable, it is acceptable to return a reference to this collection. If this collection is mutable, a newly instantiated collection must be returned. |
combinations | Source Codeshared {[Element+]*} combinations(Integer length) The combinations of elements of this collection, of the
given positive size, as a stream of nonempty
sequences. That is, a stream producing
every distinct selection of For example, "ABCD".combinations(2).map(String) is the stream of strings
If this collection is empty, the resulting stream is empty. The combinations are enumerated lexicographically according to the order in which each distinct element of this collection is first produced by its iterator. No combination is repeated. Two elements are considered distinct if either:
Parameters:
Throws
Since 1.3.0 |
contains | Source Codeshared actual default Boolean contains(Object element) Return |
Inherited Methods |
Methods inherited from: Object |
Methods inherited from: Category<Element> |
Methods inherited from: Iterable<Element,Absent> any() , by() , chain() , collect() , contains() , count() , defaultNullElements() , each() , every() , filter() , find() , findLast() , flatMap() , fold() , follow() , frequencies() , getFromFirst() , group() , indexes() , interpose() , iterator() , locate() , locateLast() , locations() , longerThan() , map() , max() , narrow() , partition() , product() , reduce() , repeat() , scan() , select() , sequence() , shorterThan() , skip() , skipWhile() , sort() , spread() , summarize() , tabulate() , take() , takeWhile() |