scala.collection
Type members
Classlikes
An extractor used to head/tail deconstruct sequences.
An extractor used to head/tail deconstruct sequences.
- Source:
- package.scala
An extractor used to init/last deconstruct sequences.
An extractor used to init/last deconstruct sequences.
- Source:
- package.scala
Explicit instantiation of the IndexedSeqView
trait to reduce class file size in subclasses.
Explicit instantiation of the IndexedSeqView
trait to reduce class file size in subclasses.
- Source:
- IndexedSeqView.scala
Explicit instantiation of the Iterable
trait to reduce class file size in subclasses.
Explicit instantiation of the Iterable
trait to reduce class file size in subclasses.
- Source:
- Iterable.scala
Explicit instantiation of the Iterator
trait to reduce class file size in subclasses.
Explicit instantiation of the Iterator
trait to reduce class file size in subclasses.
- Source:
- Iterator.scala
Explicit instantiation of the Map
trait to reduce class file size in subclasses.
Explicit instantiation of the Map
trait to reduce class file size in subclasses.
- Source:
- Map.scala
Explicit instantiation of the MapView
trait to reduce class file size in subclasses.
Explicit instantiation of the MapView
trait to reduce class file size in subclasses.
- Source:
- MapView.scala
Explicit instantiation of the Seq
trait to reduce class file size in subclasses.
Explicit instantiation of the Seq
trait to reduce class file size in subclasses.
- Source:
- Seq.scala
Explicit instantiation of the SeqView
trait to reduce class file size in subclasses.
Explicit instantiation of the SeqView
trait to reduce class file size in subclasses.
- Source:
- SeqView.scala
Explicit instantiation of the Set
trait to reduce class file size in subclasses.
Explicit instantiation of the Set
trait to reduce class file size in subclasses.
- Source:
- Set.scala
Explicit instantiation of the View
trait to reduce class file size in subclasses.
Explicit instantiation of the View
trait to reduce class file size in subclasses.
- Source:
- View.scala
A Stepper for arbitrary element types.
A Stepper for arbitrary element types. See Stepper.
- Companion:
- object
- Source:
- Stepper.scala
This class serves as a wrapper for Array
s with many of the operations found in
indexed sequences.
This class serves as a wrapper for Array
s with many of the operations found in
indexed sequences. Where needed, instances of arrays are implicitly converted
into this class. There is generally no reason to create an instance explicitly or use
an ArrayOps
type. It is better to work with plain Array
types instead and rely on
the implicit conversion to ArrayOps
when calling a method (which does not actually
allocate an instance of ArrayOps
because it is a value class).
Neither Array
nor ArrayOps
are proper collection types
(i.e. they do not extend Iterable
or even IterableOnce
). mutable.ArraySeq
and
immutable.ArraySeq
serve this purpose.
The difference between this class and ArraySeq
s is that calling transformer methods such as
filter
and map
will yield an array, whereas an ArraySeq
will remain an ArraySeq
.
- Type parameters:
- A
type of the elements contained in this array.
- Companion:
- object
- Source:
- ArrayOps.scala
Base type of bitsets.
Base type of bitsets.
This trait provides most of the operations of a BitSet
independently of its representation.
It is inherited by all concrete implementations of bitsets.
- Companion:
- object
- Source:
- BitSet.scala
- Companion:
- class
- Source:
- BitSet.scala
Base implementation type of bitsets
Base implementation type of bitsets
- Companion:
- object
- Source:
- BitSet.scala
Buffered iterators are iterators which provide a method head
that inspects the next element without discarding it.
Buffered iterators are iterators which provide a method head
that inspects the next element without discarding it.
- Source:
- BufferedIterator.scala
Builds a collection of type C
from elements of type A
when a source collection of type From
is available.
Builds a collection of type C
from elements of type A
when a source collection of type From
is available.
Implicit instances of BuildFrom
are available for all collection types.
- Type parameters:
- A
Type of elements (e.g.
Int
,Boolean
, etc.)- C
Type of collection (e.g.
List[Int]
,TreeMap[Int, String]
, etc.)- From
Type of source collection
- Companion:
- object
- Source:
- BuildFrom.scala
Base trait for companion objects of collections that require an implicit ClassTag
.
Base trait for companion objects of collections that require an implicit ClassTag
.
- Type parameters:
- CC
Collection type constructor (e.g.
ArraySeq
)
- Companion:
- object
- Source:
- Factory.scala
Base trait for companion objects of collections that require an implicit evidence.
Base trait for companion objects of collections that require an implicit evidence.
- Type parameters:
- CC
Collection type constructor (e.g.
ArraySeq
)- Ev
Unary type constructor for the implicit evidence required for an element type (typically
Ordering
orClassTag
)
- Companion:
- object
- Source:
- Factory.scala
This trait provides default implementations for the factory methods fromSpecific
and
newSpecificBuilder
that need to be refined when implementing a collection type that refines
the CC
and C
type parameters.
This trait provides default implementations for the factory methods fromSpecific
and
newSpecificBuilder
that need to be refined when implementing a collection type that refines
the CC
and C
type parameters. It is used for collections that have an additional constraint,
expressed by the evidenceIterableFactory
method.
The default implementations in this trait can be used in the common case when CC[A]
is the
same as C
.
- Source:
- Iterable.scala
A factory that builds a collection of type C
with elements of type A
.
A factory that builds a collection of type C
with elements of type A
.
This is a general form of any factory (IterableFactory, SortedIterableFactory, MapFactory and SortedMapFactory) whose element type is fixed.
- Type parameters:
- A
Type of elements (e.g.
Int
,Boolean
, etc.)- C
Type of collection (e.g.
List[Int]
,TreeMap[Int, String]
, etc.)
- Companion:
- object
- Source:
- Factory.scala
Base trait for indexed sequences that have efficient apply
and length
Base trait for indexed sequences that have efficient apply
and length
- Companion:
- object
- Source:
- IndexedSeq.scala
- Companion:
- class
- Source:
- IndexedSeq.scala
View defined in terms of indexing a range
View defined in terms of indexing a range
- Companion:
- object
- Source:
- IndexedSeqView.scala
Base trait for generic collections.
Base trait for generic collections.
- Type parameters:
- A
the element type of the collection
- Companion:
- object
- Source:
- Iterable.scala
- Companion:
- class
- Source:
- Iterable.scala
Base trait for companion objects of unconstrained collection types that may require
multiple traversals of a source collection to build a target collection CC
.
Base trait for companion objects of unconstrained collection types that may require
multiple traversals of a source collection to build a target collection CC
.
- Type parameters:
- CC
Collection type constructor (e.g.
List
)
- Companion:
- object
- Source:
- Factory.scala
This trait provides default implementations for the factory methods fromSpecific
and
newSpecificBuilder
that need to be refined when implementing a collection type that refines
the CC
and C
type parameters.
This trait provides default implementations for the factory methods fromSpecific
and
newSpecificBuilder
that need to be refined when implementing a collection type that refines
the CC
and C
type parameters.
The default implementations in this trait can be used in the common case when CC[A]
is the
same as C
.
- Source:
- Iterable.scala
A template trait for collections which can be traversed either once only or one or more times.
A template trait for collections which can be traversed either once only or one or more times.
Note: IterableOnce
does not extend IterableOnceOps. This is different than the general
design of the collections library, which uses the following pattern:
trait Seq extends Iterable with SeqOps
trait SeqOps extends IterableOps
trait IndexedSeq extends Seq with IndexedSeqOps
trait IndexedSeqOps extends SeqOps
The goal is to provide a minimal interface without any sequential operations. This allows third-party extension like Scala parallel collections to integrate at the level of IterableOnce without inheriting unwanted implementations.
- Companion:
- object
- Source:
- IterableOnce.scala
This implementation trait can be mixed into an IterableOnce
to get the basic methods that are shared between
Iterator
and Iterable
.
This implementation trait can be mixed into an IterableOnce
to get the basic methods that are shared between
Iterator
and Iterable
. The IterableOnce
must support multiple calls to iterator
but may or may not
return the same Iterator
every time.
- Source:
- IterableOnce.scala
Base trait for Iterable operations
Base trait for Iterable operations
VarianceNote
We require that for all child classes of Iterable the variance of
the child class and the variance of the C
parameter passed to IterableOps
are the same. We cannot express this since we lack variance polymorphism. That's
why we have to resort at some places to write C[A @uncheckedVariance]
.
- Type parameters:
- C
type of the collection (e.g.
List[Int]
,String
,BitSet
). Operations returning a collection with the same type of element (e.g.drop
,filter
) return aC
.- CC
type constructor of the collection (e.g.
List
,Set
). Operations returning a collection with a different type of elementB
(e.g.map
) return aCC[B]
.
- Companion:
- object
- Source:
- Iterable.scala
Iterators are data structures that allow to iterate over a sequence of elements.
Iterators are data structures that allow to iterate over a sequence
of elements. They have a hasNext
method for checking
if there is a next element available, and a next
method
which returns the next element and advances the iterator.
An iterator is mutable: most operations on it change its state. While it is often used to iterate through the elements of a collection, it can also be used without being backed by any collection (see constructors on the companion object).
It is of particular importance to note that, unless stated otherwise, one should never
use an iterator after calling a method on it. The two most important exceptions
are also the sole abstract methods: next
and hasNext
.
Both these methods can be called any number of times without having to discard the
iterator. Note that even hasNext
may cause mutation -- such as when iterating
from an input stream, where it will block until the stream is closed or some
input becomes available.
Consider this example for safe and unsafe use:
def f[A](it: Iterator[A]) = {
if (it.hasNext) { // Safe to reuse "it" after "hasNext"
it.next() // Safe to reuse "it" after "next"
val remainder = it.drop(2) // it is *not* safe to use "it" again after this line!
remainder.take(2) // it is *not* safe to use "remainder" after this line!
} else it
}
- Companion:
- object
- Source:
- Iterator.scala
- Companion:
- class
- Source:
- Iterator.scala
Decorator representing lazily zipped pairs.
Decorator representing lazily zipped pairs.
- Companion:
- object
- Source:
- LazyZipOps.scala
Decorator representing lazily zipped triples.
Decorator representing lazily zipped triples.
- Companion:
- object
- Source:
- LazyZipOps.scala
Decorator representing lazily zipped 4-tuples.
Decorator representing lazily zipped 4-tuples.
- Companion:
- object
- Source:
- LazyZipOps.scala
Base trait for linearly accessed sequences that have efficient head
and
tail
operations.
Base trait for linearly accessed sequences that have efficient head
and
tail
operations.
Known subclasses: List, LazyList
- Companion:
- object
- Source:
- LinearSeq.scala
- Companion:
- class
- Source:
- LinearSeq.scala
Base trait for linear Seq operations
Base trait for linear Seq operations
- Source:
- LinearSeq.scala
This trait provides default implementations for the factory methods fromSpecific
and
newSpecificBuilder
that need to be refined when implementing a collection type that refines
the CC
and C
type parameters.
This trait provides default implementations for the factory methods fromSpecific
and
newSpecificBuilder
that need to be refined when implementing a collection type that refines
the CC
and C
type parameters. It is used for maps.
Note that in maps, the CC
type of the map is not the same as the CC
type for the
underlying iterable (which is fixed to Map
in MapOps). This trait has therefore
two type parameters CC
and WithFilterCC
. The withFilter
method inherited from
IterableOps
is overridden with a compatible default implementation.
The default implementations in this trait can be used in the common case when CC[A]
is the
same as C
.
- Source:
- Iterable.scala
Base Map implementation type
Base Map implementation type
- Type parameters:
- C
type of the map (e.g.
HashMap[Int, String]
). Operations returning a collection with the same type of element (e.g.drop
,filter
) return aC
.- CC
type constructor of the map (e.g.
HashMap
). Operations returning a collection with a different type of entries(L, W)
(e.g.map
) return aCC[L, W]
.- K
Type of keys
- V
Type of values
- Companion:
- object
- Source:
- Map.scala
- Companion:
- object
- Source:
- MapView.scala
A generic trait for ordered maps.
A generic trait for ordered maps. Concrete classes have to provide
functionality for the abstract methods in SeqMap
.
Note that when checking for equality SeqMap does not take into account ordering.
- Type parameters:
- K
the type of the keys contained in this linked map.
- V
the type of the values associated with the keys in this linked map.
- Companion:
- object
- Source:
- SeqMap.scala
Base trait for Seq operations
Base trait for Seq operations
- Type parameters:
- A
the element type of the collection
- C
type of the collection (e.g.
List[Int]
,String
,BitSet
). Operations returning a collection with the same type of element (e.g.drop
,filter
) return aC
.- CC
type constructor of the collection (e.g.
List
,Set
). Operations returning a collection with a different type of elementB
(e.g.map
) return aCC[B]
.
- Companion:
- object
- Source:
- Seq.scala
Base trait for companion objects of collections that require an implicit Ordering
.
Base trait for companion objects of collections that require an implicit Ordering
.
- Type parameters:
- CC
Collection type constructor (e.g.
SortedSet
)
- Companion:
- object
- Source:
- Factory.scala
A Map whose keys are sorted according to a scala.math.Ordering
A Map whose keys are sorted according to a scala.math.Ordering
- Companion:
- object
- Source:
- SortedMap.scala
- Companion:
- class
- Source:
- SortedMap.scala
This trait provides default implementations for the factory methods fromSpecific
and
newSpecificBuilder
that need to be refined when implementing a collection type that refines
the CC
and C
type parameters.
This trait provides default implementations for the factory methods fromSpecific
and
newSpecificBuilder
that need to be refined when implementing a collection type that refines
the CC
and C
type parameters. It is used for sorted maps.
Note that in sorted maps, the CC
type of the map is not the same as the CC
type for the
underlying map (which is fixed to Map
in SortedMapOps). This trait has therefore
three type parameters CC
, WithFilterCC
and UnsortedCC
. The withFilter
method inherited
from IterableOps
is overridden with a compatible default implementation.
The default implementations in this trait can be used in the common case when CC[A]
is the
same as C
.
- Source:
- Iterable.scala
- Companion:
- object
- Source:
- SortedMap.scala
Base type of sorted sets
Base type of sorted sets
- Companion:
- object
- Source:
- SortedSet.scala
- Companion:
- class
- Source:
- SortedSet.scala
This trait provides default implementations for the factory methods fromSpecific
and
newSpecificBuilder
that need to be refined when implementing a collection type that refines
the CC
and C
type parameters.
This trait provides default implementations for the factory methods fromSpecific
and
newSpecificBuilder
that need to be refined when implementing a collection type that refines
the CC
and C
type parameters. It is used for sorted sets.
Note that in sorted sets, the CC
type of the set is not the same as the CC
type for the
underlying iterable (which is fixed to Set
in SortedSetOps). This trait has therefore
two type parameters CC
and WithFilterCC
. The withFilter
method inherited from
IterableOps
is overridden with a compatible default implementation.
The default implementations in this trait can be used in the common case when CC[A]
is the
same as C
.
- Source:
- Iterable.scala
- Companion:
- object
- Source:
- SortedSet.scala
- Type parameters:
- A
Type of elements (e.g.
Int
,Boolean
, etc.)- C
Type of collection (e.g.
List[Int]
,TreeMap[Int, String]
, etc.)
- Source:
- Factory.scala
Steppers exist to enable creating Java streams over Scala collections, see scala.jdk.StreamConverters.
Steppers exist to enable creating Java streams over Scala collections, see
scala.jdk.StreamConverters. Besides that use case, they allow iterating over collections
holding unboxed primitives (e.g., Array[Int]
) without boxing the elements.
Steppers have an iterator-like interface with methods hasStep
and nextStep()
. The difference
to iterators - and the reason Stepper
is not a subtype of Iterator
- is that there are
hand-specialized variants of Stepper
for Int
, Long
and Double
(IntStepper, etc.).
These enable iterating over collections holding unboxed primitives (e.g., Arrays,
scala.jdk.Accumulators) without boxing the elements.
The selection of primitive types (Int
, Long
and Double
) matches the hand-specialized
variants of Java Streams (java.util.stream.Stream, java.util.stream.IntStream, etc.)
and the corresponding Java Spliterators (java.util.Spliterator, java.util.Spliterator.OfInt, etc.).
Steppers can be converted to Scala Iterators, Java Iterators and Java Spliterators. Primitive Steppers are converted to the corresponding primitive Java Iterators and Spliterators.
- Type parameters:
- A
the element type of the Stepper
- Companion:
- object
- Source:
- Stepper.scala
An implicit StepperShape instance is used in the IterableOnce.stepper to return a possibly
specialized Stepper S
according to the element type T
.
An implicit StepperShape instance is used in the IterableOnce.stepper to return a possibly
specialized Stepper S
according to the element type T
.
- Companion:
- object
- Source:
- StepperShape.scala
Trait that overrides iterable operations to take advantage of strict builders.
Trait that overrides iterable operations to take advantage of strict builders.
- Type parameters:
- A
Elements type
- C
Collection type
- CC
Collection type constructor
- Source:
- StrictOptimizedIterableOps.scala
- Source:
- LinearSeq.scala
Trait that overrides map operations to take advantage of strict builders.
Trait that overrides map operations to take advantage of strict builders.
- Type parameters:
- C
Collection type
- CC
Collection type constructor
- K
Type of keys
- V
Type of values
- Source:
- StrictOptimizedMapOps.scala
Trait that overrides operations on sequences in order to take advantage of strict builders.
Trait that overrides operations on sequences in order to take advantage of strict builders.
- Source:
- StrictOptimizedSeqOps.scala
Trait that overrides set operations to take advantage of strict builders.
Trait that overrides set operations to take advantage of strict builders.
- Type parameters:
- A
Elements type
- C
Collection type
- CC
Collection type constructor
- Source:
- StrictOptimizedSetOps.scala
Trait that overrides sorted map operations to take advantage of strict builders.
Trait that overrides sorted map operations to take advantage of strict builders.
- Type parameters:
- C
Collection type
- CC
Collection type constructor
- K
Type of keys
- V
Type of values
- Source:
- StrictOptimizedSortedMapOps.scala
Trait that overrides sorted set operations to take advantage of strict builders.
Trait that overrides sorted set operations to take advantage of strict builders.
- Type parameters:
- A
Elements type
- C
Collection type
- CC
Collection type constructor
- Source:
- StrictOptimizedSortedSetOps.scala
Provides extension methods for strings.
Provides extension methods for strings.
Some of these methods treat strings as a plain collection of Chars without any regard for Unicode handling. Unless the user takes Unicode handling in to account or makes sure the strings don't require such handling, these methods may result in unpaired or invalidly paired surrogate code units.
- Companion:
- object
- Source:
- StringOps.scala
Views are collections whose transformation operations are non strict: the resulting elements are evaluated only when the view is effectively traversed (e.g.
Views are collections whose transformation operations are non strict: the resulting elements
are evaluated only when the view is effectively traversed (e.g. using foreach
or foldLeft
),
or when the view is converted to a strict collection type (using the to
operation).
- Companion:
- object
- Source:
- View.scala
This object reifies operations on views as case classes
This object reifies operations on views as case classes
- Companion:
- class
- Source:
- View.scala
A template trait that contains just the map
, flatMap
, foreach
and withFilter
methods
of trait Iterable
.
A template trait that contains just the map
, flatMap
, foreach
and withFilter
methods
of trait Iterable
.
- Type parameters:
- A
Element type (e.g.
Int
)- CC
Collection type constructor (e.g.
List
)
- Source:
- WithFilter.scala
Deprecated classlikes
A default map which builds a default immutable.Map
implementation for all
transformations.
A default map which builds a default immutable.Map
implementation for all
transformations.
- Deprecated
- Source:
- DefaultMap.scala
A variety of decorators that enable converting between
Scala and Java collections using extension methods, asScala
and asJava
.
A variety of decorators that enable converting between
Scala and Java collections using extension methods, asScala
and asJava
.
The extension methods return adapters for the corresponding API.
The following conversions are supported via asScala
and asJava
:
scala.collection.Iterable <=> java.lang.Iterable
scala.collection.Iterator <=> java.util.Iterator
scala.collection.mutable.Buffer <=> java.util.List
scala.collection.mutable.Set <=> java.util.Set
scala.collection.mutable.Map <=> java.util.Map
scala.collection.concurrent.Map <=> java.util.concurrent.ConcurrentMap
The following conversions are supported via asScala
and through
specially-named extension methods to convert to Java collections, as shown:
scala.collection.Iterable <=> java.util.Collection (via asJavaCollection)
scala.collection.Iterator <=> java.util.Enumeration (via asJavaEnumeration)
scala.collection.mutable.Map <=> java.util.Dictionary (via asJavaDictionary)
In addition, the following one-way conversions are provided via asJava
:
scala.collection.Seq => java.util.List
scala.collection.mutable.Seq => java.util.List
scala.collection.Set => java.util.Set
scala.collection.Map => java.util.Map
The following one way conversion is provided via asScala
:
java.util.Properties => scala.collection.mutable.Map
In all cases, converting from a source type to a target type and back again will return the original source object. For example:
import scala.collection.JavaConverters._
val source = new scala.collection.mutable.ListBuffer[Int]
val target: java.util.List[Int] = source.asJava
val other: scala.collection.mutable.Buffer[Int] = target.asScala
assert(source eq other)
Alternatively, the conversion methods have descriptive names and can be invoked explicitly.
scala> val vs = java.util.Arrays.asList("hi", "bye")
vs: java.util.List[String] = [hi, bye]
scala> val ss = asScalaIterator(vs.iterator)
ss: Iterator[String] = <iterator>
scala> .toList
res0: List[String] = List(hi, bye)
scala> val ss = asScalaBuffer(vs)
ss: scala.collection.mutable.Buffer[String] = Buffer(hi, bye)
- Deprecated
- Source:
- JavaConverters.scala
Deprecated types
- Deprecated
- Source:
- package.scala