Scala Library
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scala/collection/Map.scala
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trait
Map[A, +B]
extends
PartialFunction[A, B] with
Collection[(A, B)]A map is a collection that maps each key to one or zero values.
This trait provides a limited interface, only allowing reading of elements.
There are two extensions of this trait, in packages
scala.collection.mutable
and
scala.collection.immutable
, which provide functionality for
adding new key/value mappings to a map. The trait in the first package is
for maps that are modified destructively, whereas the trait in
the second package is for immutable maps which create a new map
when something is added or removed from them.
Method Summary | |
def
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apply
(key : A) : B
Retrieve the value which is associated with the given key. This
method throws an exception if there is no mapping from the given
key to a value.
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def
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contains
(key : A) : Boolean
Is the given key mapped to a value by this map?
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def
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default
(key : A) : B
The default value for the map, returned when a key is not found
The method implemented here yields an error,
but it might be overridden in subclasses.
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override def
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equals
(that : Any) : Boolean
Compares two maps structurally; i.e. checks if all mappings
contained in this map are also contained in the other map,
and vice versa.
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def
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filterKeys
(p : (A) => Boolean) : Projection[A, B]
non-strict filter based on keys only
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abstract def
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get
(key : A) : Option[B]
Check if this map maps
key to a value and return the
value if it exists. |
def
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getOrElse
[B2 >: B](key : A, default : => B2) : B2
Check if this map maps
key to a value.
Return that value if it exists, otherwise return default . |
override def
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hashCode
: Int
A hash method compatible with
equals |
def
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isDefinedAt
(key : A) : Boolean
Does this map contain a mapping from the given key to a value?
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override def
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isEmpty
: Boolean
Is this an empty map?
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def
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keySet : Set[A] |
def
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keys
: Iterator[A]
Creates an iterator for all keys.
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def
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mapElements
[C](f : (B) => C) : Projection[A, C]
non-strict map elements using existing key set
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override def
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projection
: Projection[A, B]
returns a projection that can be used to call non-strict
filter ,
map , and flatMap methods that build projections
of the collection. |
abstract def
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size
: Int
Compute the number of key-to-value mappings.
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protected override def
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stringPrefix
: java.lang.String
Defines the prefix of this object's
toString representation. |
override def
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toString
: java.lang.String
Creates a string representation for this map.
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def
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values
: Iterator[B]
Creates an iterator for a contained values.
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Methods inherited from Collection | |
toArray |
Methods inherited from Iterable | |
elements (abstract), concat, ++, map, flatMap, filter, partition, takeWhile, dropWhile, take, drop, foreach, forall, exists, find, findIndexOf, indexOf, foldLeft, foldRight, /:, :\, reduceLeft, reduceRight, copyToBuffer, sameElements, toList, toSeq, toStream, mkString, mkString, mkString, addString, addString, addString, copyToArray, hasDefiniteSize |
Methods inherited from PartialFunction | |
orElse, andThen |
Methods inherited from Function1 | |
compose |
Methods inherited from AnyRef | |
getClass, clone, notify, notifyAll, wait, wait, wait, finalize, ==, !=, eq, ne, synchronized |
Methods inherited from Any | |
==, !=, isInstanceOf, asInstanceOf |
Method Details |
abstract
def
size : Int
key
to a value and return the
value if it exists.key -
the key of the mapping of interestkey
to a value.
Return that value if it exists, otherwise return default
.override
def
isEmpty : Boolean
true
iff the map is empty.key -
the keykey -
the keytrue
iff there is a mapping for key in this mapkey -
the keytrue
iff there is a mapping for key in this mapthat -
the other maptrue
iff both maps contain exactly the same mappings.override
def
hashCode : Int
equals
override
def
toString : java.lang.String
key -
the given key valueoverride
def
projection : Projection[A, B]
filter
,
map
, and flatMap
methods that build projections
of the collection.
def
filterKeys(p : (A) => Boolean) : Projection[A, B]
def
mapElements[C](f : (B) => C) : Projection[A, C]
protected override
def
stringPrefix : java.lang.String
toString
representation.
Scala Library
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