Scala Library: scala.collection.mutable.HashMap
scala.collection.mutable.HashMap
This class implements mutable maps using a hashtable.
- A
- the type of the keys contained in this hash map.
- B
- the type of the values assigned to keys in this hash map.
- Annotations
- @ SerialVersionUID ()
- Source
- Since
- 1
- See also
- “Scala’s Collection Library overview”
section on
Hash Tables
for more information.
- “Scala’s Collection Library overview”
section on
Type Members
class DefaultKeySet extends AbstractSet[A] with Set[A] with Serializable
The implementation class of the set returned by keySet
.
- Attributes
- protected
- Definition Classes
- MapLike
class DefaultValuesIterable extends AbstractIterable[B] with Iterable[B] with Serializable
The implementation class of the iterable returned by values
.
- Attributes
- protected
- Definition Classes
- MapLike
type Entry = DefaultEntry[A, B]
class FilteredKeys extends AbstractMap[A, B] with DefaultMap[A, B]
- Attributes
- protected
- Definition Classes
- MapLike
class MappedValues[C] extends AbstractMap[A, C] with DefaultMap[A, C]
- Attributes
- protected
- Definition Classes
- MapLike
type Self = HashMap[A, B]
The type implementing this traversable
- Attributes
- protected[this]
- Definition Classes
- TraversableLike
class WithFilter extends FilterMonadic[A, Repr]
A class supporting filtered operations. Instances of this class are returned by
method withFilter
.
- Definition Classes
- TraversableLike
Value Members From scala.Function1
def compose[A](g: (A) ⇒ A): (A) ⇒ B
Composes two instances of Function1 in a new Function1, with this function applied last.
- A
- the type to which function
g
can be applied
- the type to which function
- g
- a function A => T1
- returns
- a new function
f
such thatf(x) == apply(g(x))
- a new function
- Definition Classes
- Function1
- Annotations
- @ unspecialized ()
(defined at scala.Function1)
Value Members From scala.PartialFunction
def andThen[C](k: (B) ⇒ C): PartialFunction[A, C]
Composes this partial function with a transformation function that gets applied to results of this partial function.
- C
- the result type of the transformation function.
- k
- the transformation function
- returns
- a partial function with the same domain as this partial function, which maps
arguments
x
tok(this(x))
.
- a partial function with the same domain as this partial function, which maps
arguments
- Definition Classes
- PartialFunction → Function1
(defined at scala.PartialFunction)
def applyOrElse[A1 <: A, B1 >: B](x: A1, default: (A1) ⇒ B1): B1
Applies this partial function to the given argument when it is contained in the function domain. Applies fallback function where this partial function is not defined.
Note that expression pf.applyOrElse(x, default)
is equivalent to
except that applyOrElse
method can be implemented more efficiently. For all
partial function literals the compiler generates an applyOrElse
implementation
which avoids double evaluation of pattern matchers and guards. This makes
applyOrElse
the basis for the efficient implementation for many operations
and scenarios, such as:
- combining partial functions into
orElse
/andThen
chains does not lead to excessiveapply
/isDefinedAt
evaluation lift
andunlift
do not evaluate source functions twice on each invocationrunWith
allows efficient imperative-style combining of partial functions with conditionally applied actions
For non-literal partial function classes with nontrivial isDefinedAt
method it
is recommended to override applyOrElse
with custom implementation that avoids
double isDefinedAt
evaluation. This may result in better performance and more
predictable behavior w.r.t. side effects.
- x
- the function argument
- default
- the fallback function
- returns
- the result of this function or fallback function application.
- Definition Classes
- PartialFunction
- Since
- 2.10
(defined at scala.PartialFunction)
def lift: (A) ⇒ Option[B]
Turns this partial function into a plain function returning an Option
result.
- returns
- a function that takes an argument
x
toSome(this(x))
ifthis
is defined forx
, and toNone
otherwise.
- a function that takes an argument
- Definition Classes
- PartialFunction
- See also
- Function.unlift
(defined at scala.PartialFunction)
def orElse[A1 <: A, B1 >: B](that: PartialFunction[A1, B1]): PartialFunction[A1, B1]
Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.
- A1
- the argument type of the fallback function
- B1
- the result type of the fallback function
- that
- the fallback function
- returns
- a partial function which has as domain the union of the domains of this
partial function and
that
. The resulting partial function takesx
tothis(x)
wherethis
is defined, and tothat(x)
where it is not.
- a partial function which has as domain the union of the domains of this
partial function and
- Definition Classes
- PartialFunction
(defined at scala.PartialFunction)
def runWith[U](action: (B) ⇒ U): (A) ⇒ Boolean
Composes this partial function with an action function which gets applied to results of this partial function. The action function is invoked only for its side effects; its result is ignored.
Note that expression pf.runWith(action)(x)
is equivalent to
except that runWith
is implemented via applyOrElse
and thus potentially more
efficient. Using runWith
avoids double evaluation of pattern matchers and
guards for partial function literals.
- action
- the action function
- returns
- a function which maps arguments
x
toisDefinedAt(x)
. The resulting function runsaction(this(x))
wherethis
is defined.
- a function which maps arguments
- Definition Classes
- PartialFunction
- Since
- 2.10
- See also
applyOrElse
.
(defined at scala.PartialFunction)
Value Members From scala.collection.CustomParallelizable
def parCombiner: Combiner[(A, B), ParHashMap[A, B]]
The default par
implementation uses the combiner provided by this method to
create a new parallel collection.
- returns
- a combiner for the parallel collection of type
ParRepr
- a combiner for the parallel collection of type
- Attributes
- protected[this]
- Definition Classes
- CustomParallelizable → Parallelizable
(defined at scala.collection.CustomParallelizable)
Value Members From scala.collection.GenMapLike
def 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.
- that
- the other map
- returns
true
if both maps contain exactly the same mappings,false
otherwise.
- Definition Classes
- GenMapLike → Equals → AnyRef → Any
(defined at scala.collection.GenMapLike)
Value Members From scala.collection.IterableLike
def canEqual(that: Any): Boolean
Method called from equality methods, so that user-defined subclasses can refuse to be equal to other collections of the same kind.
- that
- The object with which this iterable collection should be compared
- returns
true
, if this iterable collection can possibly equalthat
,false
otherwise. The test takes into consideration only the run-time types of objects but ignores their elements.
- Definition Classes
- IterableLike → Equals
(defined at scala.collection.IterableLike)
def copyToArray[B >: (A, B)](xs: Array[B], start: Int, len: Int): Unit
[use case]
Copies the elements of this mutable hash map to an array. Fills the given array
xs
with at most len
elements of this mutable hash map, starting at position
start
. Copying will stop once either the end of the current mutable hash map
is reached, or the end of the target array is reached, or len
elements have
been copied.
- xs
- the array to fill.
- start
- the starting index.
- len
- the maximal number of elements to copy.
- Definition Classes
- IterableLike → TraversableLike → TraversableOnce → GenTraversableOnce
(defined at scala.collection.IterableLike)
def drop(n: Int): HashMap[A, B]
Selects all elements except first n ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
- the number of elements to drop from this iterable collection.
- returns
- a iterable collection consisting of all elements of this iterable collection
except the first
n
ones, or else the empty iterable collection, if this iterable collection has less thann
elements.
- a iterable collection consisting of all elements of this iterable collection
except the first
- Definition Classes
- IterableLike → TraversableLike → GenTraversableLike
(defined at scala.collection.IterableLike)
def dropRight(n: Int): HashMap[A, B]
Selects all elements except last n ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
- The number of elements to take
- returns
- a iterable collection consisting of all elements of this iterable collection
except the last
n
ones, or else the empty iterable collection, if this iterable collection has less thann
elements.
- a iterable collection consisting of all elements of this iterable collection
except the last
- Definition Classes
- IterableLike
(defined at scala.collection.IterableLike)
def exists(p: ((A, B)) ⇒ Boolean): Boolean
Tests whether a predicate holds for at least one element of this iterable collection.
Note: may not terminate for infinite-sized collections.
- p
- the predicate used to test elements.
- returns
false
if this iterable collection is empty, otherwisetrue
if the given predicatep
holds for some of the elements of this iterable collection, otherwisefalse
- Definition Classes
- IterableLike → TraversableLike → TraversableOnce → GenTraversableOnce
(defined at scala.collection.IterableLike)
def find(p: ((A, B)) ⇒ Boolean): Option[(A, B)]
Finds the first element of the iterable collection satisfying a predicate, if any.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- p
- the predicate used to test elements.
- returns
- an option value containing the first element in the iterable collection that
satisfies
p
, orNone
if none exists.
- an option value containing the first element in the iterable collection that
satisfies
- Definition Classes
- IterableLike → TraversableLike → TraversableOnce → GenTraversableOnce
(defined at scala.collection.IterableLike)
def foldRight[B](z: B)(op: ((A, B), B) ⇒ B): B
Applies a binary operator to all elements of this iterable collection and a start value, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.
- B
- the result type of the binary operator.
- z
- the start value.
- op
- the binary operator.
- returns
- the result of inserting
op
between consecutive elements of this iterable collection, going right to left with the start valuez
on the right:
- the result of inserting
where `x1, ..., xn` are the elements of this iterable collection. Returns
`z` if this iterable collection is empty.
- Definition Classes
- IterableLike → TraversableOnce → GenTraversableOnce
(defined at scala.collection.IterableLike)
def forall(p: ((A, B)) ⇒ Boolean): Boolean
Tests whether a predicate holds for all elements of this iterable collection.
Note: may not terminate for infinite-sized collections.
- p
- the predicate used to test elements.
- returns
true
if this iterable collection is empty or the given predicatep
holds for all elements of this iterable collection, otherwisefalse
.
- Definition Classes
- IterableLike → TraversableLike → TraversableOnce → GenTraversableOnce
(defined at scala.collection.IterableLike)
def grouped(size: Int): Iterator[HashMap[A, B]]
Partitions elements in fixed size iterable collections.
- size
- the number of elements per group
- returns
- An iterator producing iterable collections of size
size
, except the last will be less than sizesize
if the elements don’t divide evenly.
- An iterator producing iterable collections of size
- Definition Classes
- IterableLike
- See also
- scala.collection.Iterator, method
grouped
- scala.collection.Iterator, method
(defined at scala.collection.IterableLike)
def head: (A, B)
Selects the first element of this iterable collection.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
- the first element of this iterable collection.
- Definition Classes
- IterableLike → TraversableLike → GenTraversableLike
- Exceptions thrown
- NoSuchElementException if the iterable collection is empty.
(defined at scala.collection.IterableLike)
def reduceRight[B >: (A, B)](op: ((A, B), B) ⇒ B): B
Applies a binary operator to all elements of this iterable collection, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.
- B
- the result type of the binary operator.
- op
- the binary operator.
- returns
- the result of inserting
op
between consecutive elements of this iterable collection, going right to left:
- the result of inserting
where `x1, ..., xn` are the elements of this iterable collection.
- Definition Classes
- IterableLike → TraversableOnce → GenTraversableOnce
- Exceptions thrown
- UnsupportedOperationException if this iterable collection is empty.
(defined at scala.collection.IterableLike)
def sameElements[B >: (A, B)](that: GenIterable[B]): Boolean
[use case]
Checks if the other iterable collection contains the same elements in the same order as this mutable hash map.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- that
- the collection to compare with.
- returns
true
, if both collections contain the same elements in the same order,false
otherwise.
- Definition Classes
- IterableLike → GenIterableLike
(defined at scala.collection.IterableLike)
def slice(from: Int, until: Int): HashMap[A, B]
Selects an interval of elements. The returned collection is made up of all
elements x
which satisfy the invariant:
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
- a iterable collection containing the elements greater than or equal to index
from
extending up to (but not including) indexuntil
of this iterable collection.
- a iterable collection containing the elements greater than or equal to index
- Definition Classes
- IterableLike → TraversableLike → GenTraversableLike
(defined at scala.collection.IterableLike)
def sliding(size: Int): Iterator[HashMap[A, B]]
Groups elements in fixed size blocks by passing a “sliding window” over them (as opposed to partitioning them, as is done in grouped.) “Sliding window” step is 1 by default.
- size
- the number of elements per group
- returns
- An iterator producing iterable collections of size
size
, except the last and the only element will be truncated if there are fewer elements than size.
- An iterator producing iterable collections of size
- Definition Classes
- IterableLike
- See also
- scala.collection.Iterator, method
sliding
- scala.collection.Iterator, method
(defined at scala.collection.IterableLike)
def sliding(size: Int, step: Int): Iterator[HashMap[A, B]]
Groups elements in fixed size blocks by passing a “sliding window” over them (as opposed to partitioning them, as is done in grouped.)
- size
- the number of elements per group
- step
- the distance between the first elements of successive groups
- returns
- An iterator producing iterable collections of size
size
, except the last and the only element will be truncated if there are fewer elements than size.
- An iterator producing iterable collections of size
- Definition Classes
- IterableLike
- See also
- scala.collection.Iterator, method
sliding
- scala.collection.Iterator, method
(defined at scala.collection.IterableLike)
def take(n: Int): HashMap[A, B]
Selects first n elements.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
- the number of elements to take from this iterable collection.
- returns
- a iterable collection consisting only of the first
n
elements of this iterable collection, or else the whole iterable collection, if it has less thann
elements.
- a iterable collection consisting only of the first
- Definition Classes
- IterableLike → TraversableLike → GenTraversableLike
(defined at scala.collection.IterableLike)
def takeRight(n: Int): HashMap[A, B]
Selects last n elements.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
- the number of elements to take
- returns
- a iterable collection consisting only of the last
n
elements of this iterable collection, or else the whole iterable collection, if it has less thann
elements.
- a iterable collection consisting only of the last
- Definition Classes
- IterableLike
(defined at scala.collection.IterableLike)
def takeWhile(p: ((A, B)) ⇒ Boolean): HashMap[A, B]
Takes longest prefix of elements that satisfy a predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
- the longest prefix of this iterable collection whose elements all satisfy
the predicate
p
.
- the longest prefix of this iterable collection whose elements all satisfy
the predicate
- Definition Classes
- IterableLike → TraversableLike → GenTraversableLike
(defined at scala.collection.IterableLike)
def thisCollection: collection.Iterable[(A, B)]
The underlying collection seen as an instance of Iterable
. By default this is
implemented as the current collection object itself, but this can be overridden.
- Attributes
- protected[this]
- Definition Classes
- IterableLike → TraversableLike
(defined at scala.collection.IterableLike)
def toCollection(repr: HashMap[A, B]): collection.Iterable[(A, B)]
A conversion from collections of type Repr
to Iterable
objects. By default
this is implemented as just a cast, but this can be overridden.
- Attributes
- protected[this]
- Definition Classes
- IterableLike → TraversableLike
(defined at scala.collection.IterableLike)
def toIterable: collection.Iterable[(A, B)]
Returns this iterable collection as an iterable collection.
A new collection will not be built; lazy collections will stay lazy.
Note: will not terminate for infinite-sized collections.
- returns
- an
Iterable
containing all elements of this iterable collection.
- an
- Definition Classes
- IterableLike → TraversableOnce → GenTraversableOnce
(defined at scala.collection.IterableLike)
def toIterator: Iterator[(A, B)]
Returns an Iterator over the elements in this iterable collection. Produces the
same result as iterator
.
Note: will not terminate for infinite-sized collections.
- returns
- an Iterator containing all elements of this iterable collection.
- Definition Classes
- IterableLike → TraversableLike → GenTraversableOnce
- Annotations
- @ deprecatedOverriding (message =…, since = “2.11.0”)
(defined at scala.collection.IterableLike)
def toStream: immutable.Stream[(A, B)]
Converts this iterable collection to a stream.
- returns
- a stream containing all elements of this iterable collection.
- Definition Classes
- IterableLike → TraversableLike → GenTraversableOnce
(defined at scala.collection.IterableLike)
def view(from: Int, until: Int): IterableView[(A, B), HashMap[A, B]]
Creates a non-strict view of a slice of this iterable collection.
Note: the difference between view
and slice
is that view
produces a view
of the current iterable collection, whereas slice
produces a new iterable
collection.
Note: view(from, to)
is equivalent to view.slice(from, to)
Note: might return different results for different runs, unless the underlying collection type is ordered.
- from
- the index of the first element of the view
- until
- the index of the element following the view
- returns
- a non-strict view of a slice of this iterable collection, starting at index
from
and extending up to (but not including) indexuntil
.
- a non-strict view of a slice of this iterable collection, starting at index
- Definition Classes
- IterableLike → TraversableLike
(defined at scala.collection.IterableLike)
def view: IterableView[(A, B), HashMap[A, B]]
Creates a non-strict view of this iterable collection.
- returns
- a non-strict view of this iterable collection.
- Definition Classes
- IterableLike → TraversableLike
(defined at scala.collection.IterableLike)
def zipAll[B, A1 >: (A, B), That](that: GenIterable[B], thisElem: A1, thatElem: B)(implicit bf: CanBuildFrom[HashMap[A, B], (A1, B), That]): That
[use case]
Returns a mutable hash map formed from this mutable hash map and another iterable collection by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- B
- the type of the second half of the returned pairs
- that
- The iterable providing the second half of each result pair
- thisElem
- the element to be used to fill up the result if this mutable hash map is
shorter than
that
.
- the element to be used to fill up the result if this mutable hash map is
shorter than
- thatElem
- the element to be used to fill up the result if
that
is shorter than this mutable hash map.
- the element to be used to fill up the result if
- returns
- a new mutable hash map containing pairs consisting of corresponding elements
of this mutable hash map and
that
. The length of the returned collection is the maximum of the lengths of this mutable hash map andthat
. If this mutable hash map is shorter thanthat
,thisElem
values are used to pad the result. Ifthat
is shorter than this mutable hash map,thatElem
values are used to pad the result.
- a new mutable hash map containing pairs consisting of corresponding elements
of this mutable hash map and
- Definition Classes
- IterableLike → GenIterableLike
(defined at scala.collection.IterableLike)
def zipWithIndex[A1 >: (A, B), That](implicit bf: CanBuildFrom[HashMap[A, B], (A1, Int), That]): That
[use case]
Zips this mutable hash map with its indices.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
- A new mutable hash map containing pairs consisting of all elements of this
mutable hash map paired with their index. Indices start at
0
.
- A new mutable hash map containing pairs consisting of all elements of this
mutable hash map paired with their index. Indices start at
- Definition Classes
- IterableLike → GenIterableLike
Example:
(defined at scala.collection.IterableLike)
def zip[A1 >: (A, B), B, That](that: GenIterable[B])(implicit bf: CanBuildFrom[HashMap[A, B], (A1, B), That]): That
[use case]
Returns a mutable hash map formed from this mutable hash map and another iterable collection by combining corresponding elements in pairs. If one of the two collections is longer than the other, its remaining elements are ignored.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- B
- the type of the second half of the returned pairs
- that
- The iterable providing the second half of each result pair
- returns
- a new mutable hash map containing pairs consisting of corresponding elements
of this mutable hash map and
that
. The length of the returned collection is the minimum of the lengths of this mutable hash map andthat
.
- a new mutable hash map containing pairs consisting of corresponding elements
of this mutable hash map and
- Definition Classes
- IterableLike → GenIterableLike
(defined at scala.collection.IterableLike)
Value Members From scala.collection.MapLike
def addString(b: scala.StringBuilder, start: String, sep: String, end: String): scala.StringBuilder
Appends all bindings of this map to a string builder using start, end, and
separator strings. The written text begins with the string start
and ends with
the string end
. Inside, the string representations of all bindings of this
map in the form of key -> value
are separated by the string sep
.
- b
- the builder to which strings are appended.
- start
- the starting string.
- sep
- the separator string.
- end
- the ending string.
- returns
- the string builder
b
to which elements were appended.
- the string builder
- Definition Classes
- MapLike → TraversableOnce
(defined at scala.collection.MapLike)
def default(key: A): B
Defines the default value computation for the map, returned when a key is not found The method implemented here throws an exception, but it might be overridden in subclasses.
- key
- the given key value for which a binding is missing.
- Definition Classes
- MapLike → GenMapLike
- Exceptions thrown *
(defined at scala.collection.MapLike)
def filterKeys(p: (A) ⇒ Boolean): collection.Map[A, B]
Filters this map by retaining only keys satisfying a predicate.
Note : the predicate must accept any key of type A
, not just those already
present in the map, as the predicate is tested before the underlying map is
queried.
- p
- the predicate used to test keys
- returns
- an immutable map consisting only of those key value pairs of this map where
the key satisfies the predicate
p
. The resulting map wraps the original map without copying any elements.
- an immutable map consisting only of those key value pairs of this map where
the key satisfies the predicate
- Definition Classes
- MapLike → GenMapLike
(defined at scala.collection.MapLike)
def filterNot(p: ((A, B)) ⇒ Boolean): HashMap[A, B]
Returns a new map obtained by removing all key/value pairs for which the
predicate p
returns true
.
Note: This method works by successively removing elements for which the
predicate is true from this set. If removal is slow, or you expect that most
elements of the set will be removed, you might consider using filter
with a
negated predicate instead.
- p
- A predicate over key-value pairs
- returns
- A new map containing elements not satisfying the predicate.
- Definition Classes
- MapLike → TraversableLike → GenTraversableLike
(defined at scala.collection.MapLike)
def getOrElse[B1 >: B](key: A, default: ⇒ B1): B1
[use case]
Returns the value associated with a key, or a default value if the key is not contained in the map.
- key
- the key.
- default
- a computation that yields a default value in case no binding for
key
is found in the map.
- a computation that yields a default value in case no binding for
- returns
- the value associated with
key
if it exists, otherwise the result of thedefault
computation.
- the value associated with
- Definition Classes
- MapLike → GenMapLike
(defined at scala.collection.MapLike)
def isDefinedAt(key: A): Boolean
Tests whether this map contains a binding for a key. This method, which
implements an abstract method of trait PartialFunction
, is equivalent to
contains
.
- key
- the key
- returns
true
if there is a binding forkey
in this map,false
otherwise.
- Definition Classes
- MapLike → GenMapLike → PartialFunction
(defined at scala.collection.MapLike)
def keys: collection.Iterable[A]
Collects all keys of this map in an iterable collection.
- returns
- the keys of this map as an iterable.
- Definition Classes
- MapLike → GenMapLike
- Annotations
- @migration
- Migration
- (Changed in version 2.8.0)
keys
returnsIterable[A]
rather thanIterator[A]
.
- (Changed in version 2.8.0)
(defined at scala.collection.MapLike)
def mapValues[C](f: (B) ⇒ C): collection.Map[A, C]
Transforms this map by applying a function to every retrieved value.
- f
- the function used to transform values of this map.
- returns
- a map view which maps every key of this map to
f(this(key))
. The resulting map wraps the original map without copying any elements.
- a map view which maps every key of this map to
- Definition Classes
- MapLike → GenMapLike
(defined at scala.collection.MapLike)
def toBuffer[C >: (A, B)]: Buffer[C]
Uses the contents of this map to create a new mutable buffer.
- returns
- a buffer containing all elements of this map.
- Definition Classes
- MapLike → TraversableOnce → GenTraversableOnce
(defined at scala.collection.MapLike)
Value Members From scala.collection.TraversableLike
def ++:[B >: (A, B), That](that: collection.Traversable[B])(implicit bf: CanBuildFrom[HashMap[A, B], B, That]): That
As with ++
, returns a new collection containing the elements from the left
operand followed by the elements from the right operand.
It differs from ++
in that the right operand determines the type of the
resulting collection rather than the left one. Mnemonic: the COLon is on the
side of the new COLlection type.
Example:
This overload exists because: for the implementation of ++:
we should reuse
that of ++
because many collections override it with more efficient versions.
Since TraversableOnce
has no ++
method, we have to implement that directly,
but Traversable
and down can use the overload.
- B
- the element type of the returned collection.
- That
- the class of the returned collection. Where possible,
That
is the same class as the current collection classRepr
, but this depends on the element typeB
being admissible for that class, which means that an implicit instance of typeCanBuildFrom[Repr, B, That]
is found.
- the class of the returned collection. Where possible,
- that
- the traversable to append.
- bf
- an implicit value of class
CanBuildFrom
which determines the result classThat
from the current representation typeRepr
and and the new element typeB
.
- an implicit value of class
- returns
- a new collection of type
That
which contains all elements of this traversable collection followed by all elements ofthat
.
- a new collection of type
- Definition Classes
- TraversableLike
(defined at scala.collection.TraversableLike)
def ++:[B >: (A, B), That](that: TraversableOnce[B])(implicit bf: CanBuildFrom[HashMap[A, B], B, That]): That
[use case]
As with ++
, returns a new collection containing the elements from the left
operand followed by the elements from the right operand.
It differs from ++
in that the right operand determines the type of the
resulting collection rather than the left one. Mnemonic: the COLon is on the
side of the new COLlection type.
Example:
- B
- the element type of the returned collection.
- that
- the traversable to append.
- returns
- a new mutable hash map which contains all elements of this mutable hash map
followed by all elements of
that
.
- a new mutable hash map which contains all elements of this mutable hash map
followed by all elements of
- Definition Classes
- TraversableLike
(defined at scala.collection.TraversableLike)
def ++[B >: (A, B), That](that: GenTraversableOnce[B])(implicit bf: CanBuildFrom[HashMap[A, B], B, That]): That
[use case]
Returns a new mutable hash map containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the mutable hash map is the most specific superclass encompassing the element types of the two operands.
Example:
- B
- the element type of the returned collection.
- that
- the traversable to append.
- returns
- a new mutable hash map which contains all elements of this mutable hash map
followed by all elements of
that
.
- a new mutable hash map which contains all elements of this mutable hash map
followed by all elements of
- Definition Classes
- TraversableLike → GenTraversableLike
(defined at scala.collection.TraversableLike)
def collect[B, That](pf: PartialFunction[(A, B), B])(implicit bf: CanBuildFrom[HashMap[A, B], B, That]): That
[use case]
Builds a new collection by applying a partial function to all elements of this mutable hash map on which the function is defined.
- B
- the element type of the returned collection.
- pf
- the partial function which filters and maps the mutable hash map.
- returns
- a new mutable hash map resulting from applying the given partial function
pf
to each element on which it is defined and collecting the results. The order of the elements is preserved.
- a new mutable hash map resulting from applying the given partial function
- Definition Classes
- TraversableLike → GenTraversableLike
(defined at scala.collection.TraversableLike)
def dropWhile(p: ((A, B)) ⇒ Boolean): HashMap[A, B]
Drops longest prefix of elements that satisfy a predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
- the longest suffix of this traversable collection whose first element does
not satisfy the predicate
p
.
- the longest suffix of this traversable collection whose first element does
not satisfy the predicate
- Definition Classes
- TraversableLike → GenTraversableLike
(defined at scala.collection.TraversableLike)
def filter(p: ((A, B)) ⇒ Boolean): HashMap[A, B]
Selects all elements of this traversable collection which satisfy a predicate.
- p
- the predicate used to test elements.
- returns
- a new traversable collection consisting of all elements of this traversable
collection that satisfy the given predicate
p
. The order of the elements is preserved.
- a new traversable collection consisting of all elements of this traversable
collection that satisfy the given predicate
- Definition Classes
- TraversableLike → GenTraversableLike
(defined at scala.collection.TraversableLike)
def flatMap[B, That](f: ((A, B)) ⇒ GenTraversableOnce[B])(implicit bf: CanBuildFrom[HashMap[A, B], B, That]): That
[use case]
Builds a new collection by applying a function to all elements of this mutable hash map and using the elements of the resulting collections.
For example:
The type of the resulting collection is guided by the static type of mutable hash map. This might cause unexpected results sometimes. For example:
- B
- the element type of the returned collection.
- f
- the function to apply to each element.
- returns
- a new mutable hash map resulting from applying the given collection-valued
function
f
to each element of this mutable hash map and concatenating the results.
- a new mutable hash map resulting from applying the given collection-valued
function
- Definition Classes
- TraversableLike → GenTraversableLike → FilterMonadic
(defined at scala.collection.TraversableLike)
def groupBy[K](f: ((A, B)) ⇒ K): immutable.Map[K, HashMap[A, B]]
Partitions this traversable collection into a map of traversable collections according to some discriminator function.
Note: this method is not re-implemented by views. This means when applied to a view it will always force the view and return a new traversable collection.
- K
- the type of keys returned by the discriminator function.
- f
- the discriminator function.
- returns
- A map from keys to traversable collections such that the following invariant holds:
That is, every key `k` is bound to a traversable collection of those
elements `x` for which `f(x)` equals `k` .
- Definition Classes
- TraversableLike → GenTraversableLike
(defined at scala.collection.TraversableLike)
def headOption: Option[(A, B)]
Optionally selects the first element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
- the first element of this traversable collection if it is nonempty,
None
if it is empty.
- the first element of this traversable collection if it is nonempty,
- Definition Classes
- TraversableLike → GenTraversableLike
(defined at scala.collection.TraversableLike)
def init: HashMap[A, B]
Selects all elements except the last.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
- a traversable collection consisting of all elements of this traversable collection except the last one.
- Definition Classes
- TraversableLike → GenTraversableLike
- Exceptions thrown
- UnsupportedOperationException if the traversable collection is empty.
(defined at scala.collection.TraversableLike)
def inits: Iterator[HashMap[A, B]]
Iterates over the inits of this traversable collection. The first value will be
this traversable collection and the final one will be an empty traversable
collection, with the intervening values the results of successive applications
of init
.
- returns
- an iterator over all the inits of this traversable collection
- Definition Classes
- TraversableLike
Example:
(defined at scala.collection.TraversableLike)
def last: (A, B)
Selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
- The last element of this traversable collection.
- Definition Classes
- TraversableLike → GenTraversableLike
- Exceptions thrown
- NoSuchElementException If the traversable collection is empty.
(defined at scala.collection.TraversableLike)
def lastOption: Option[(A, B)]
Optionally selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
- the last element of this traversable collection$ if it is nonempty,
None
if it is empty.
- the last element of this traversable collection$ if it is nonempty,
- Definition Classes
- TraversableLike → GenTraversableLike
(defined at scala.collection.TraversableLike)
def map[B, That](f: ((A, B)) ⇒ B)(implicit bf: CanBuildFrom[HashMap[A, B], B, That]): That
[use case]
Builds a new collection by applying a function to all elements of this mutable hash map.
- B
- the element type of the returned collection.
- f
- the function to apply to each element.
- returns
- a new mutable hash map resulting from applying the given function
f
to each element of this mutable hash map and collecting the results.
- a new mutable hash map resulting from applying the given function
- Definition Classes
- TraversableLike → GenTraversableLike → FilterMonadic
(defined at scala.collection.TraversableLike)
def partition(p: ((A, B)) ⇒ Boolean): (HashMap[A, B], HashMap[A, B])
Partitions this traversable collection in two traversable collections according to a predicate.
- p
- the predicate on which to partition.
- returns
- a pair of traversable collections: the first traversable collection consists
of all elements that satisfy the predicate
p
and the second traversable collection consists of all elements that don’t. The relative order of the elements in the resulting traversable collections is the same as in the original traversable collection.
- a pair of traversable collections: the first traversable collection consists
of all elements that satisfy the predicate
- Definition Classes
- TraversableLike → GenTraversableLike
(defined at scala.collection.TraversableLike)
def repr: HashMap[A, B]
The collection of type traversable collection underlying this TraversableLike
object. By default this is implemented as the TraversableLike
object itself,
but this can be overridden.
- Definition Classes
- TraversableLike → GenTraversableLike
(defined at scala.collection.TraversableLike)
def scanLeft[B, That](z: B)(op: (B, (A, B)) ⇒ B)(implicit bf: CanBuildFrom[HashMap[A, B], B, That]): That
Produces a collection containing cumulative results of applying the operator going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- B
- the type of the elements in the resulting collection
- That
- the actual type of the resulting collection
- z
- the initial value
- op
- the binary operator applied to the intermediate result and the element
- bf
- an implicit value of class
CanBuildFrom
which determines the result classThat
from the current representation typeRepr
and and the new element typeB
.
- an implicit value of class
- returns
- collection with intermediate results
- Definition Classes
- TraversableLike → GenTraversableLike
(defined at scala.collection.TraversableLike)
def scanRight[B, That](z: B)(op: ((A, B), B) ⇒ B)(implicit bf: CanBuildFrom[HashMap[A, B], B, That]): That
Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Example:
- B
- the type of the elements in the resulting collection
- That
- the actual type of the resulting collection
- z
- the initial value
- op
- the binary operator applied to the intermediate result and the element
- bf
- an implicit value of class
CanBuildFrom
which determines the result classThat
from the current representation typeRepr
and and the new element typeB
.
- an implicit value of class
- returns
- collection with intermediate results
- Definition Classes
- TraversableLike → GenTraversableLike
- Annotations
- @migration
- Migration
- (Changed in version 2.9.0) The behavior of
scanRight
has changed. The previous behavior can be reproduced with scanRight.reverse.
- (Changed in version 2.9.0) The behavior of
(defined at scala.collection.TraversableLike)
def scan[B >: (A, B), That](z: B)(op: (B, B) ⇒ B)(implicit cbf: CanBuildFrom[HashMap[A, B], B, That]): That
Computes a prefix scan of the elements of the collection.
Note: The neutral element z
may be applied more than once.
- B
- element type of the resulting collection
- That
- type of the resulting collection
- z
- neutral element for the operator
op
- neutral element for the operator
- op
- the associative operator for the scan
- cbf
- combiner factory which provides a combiner
- returns
- a new traversable collection containing the prefix scan of the elements in this traversable collection
- Definition Classes
- TraversableLike → GenTraversableLike
(defined at scala.collection.TraversableLike)
def span(p: ((A, B)) ⇒ Boolean): (HashMap[A, B], HashMap[A, B])
Splits this traversable collection into a prefix/suffix pair according to a predicate.
Note: c span p
is equivalent to (but possibly more efficient than)
(c takeWhile p, c dropWhile p)
, provided the evaluation of the predicate
p
does not cause any side-effects.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
- a pair consisting of the longest prefix of this traversable collection whose
elements all satisfy
p
, and the rest of this traversable collection.
- a pair consisting of the longest prefix of this traversable collection whose
elements all satisfy
- Definition Classes
- TraversableLike → GenTraversableLike
(defined at scala.collection.TraversableLike)
def splitAt(n: Int): (HashMap[A, B], HashMap[A, B])
Splits this traversable collection into two at a given position. Note:
c splitAt n
is equivalent to (but possibly more efficient than)
(c take n, c drop n)
.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
- the position at which to split.
- returns
- a pair of traversable collections consisting of the first
n
elements of this traversable collection, and the other elements.
- a pair of traversable collections consisting of the first
- Definition Classes
- TraversableLike → GenTraversableLike
(defined at scala.collection.TraversableLike)
def tail: HashMap[A, B]
Selects all elements except the first.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
- a traversable collection consisting of all elements of this traversable collection except the first one.
- Definition Classes
- TraversableLike → GenTraversableLike
- Exceptions thrown
UnsupportedOperationException
if the traversable collection is empty.
(defined at scala.collection.TraversableLike)
def tails: Iterator[HashMap[A, B]]
Iterates over the tails of this traversable collection. The first value will be
this traversable collection and the final one will be an empty traversable
collection, with the intervening values the results of successive applications
of tail
.
- returns
- an iterator over all the tails of this traversable collection
- Definition Classes
- TraversableLike
Example:
(defined at scala.collection.TraversableLike)
def toTraversable: collection.Traversable[(A, B)]
Converts this traversable collection to an unspecified Traversable. Will return the same collection if this instance is already Traversable.
Note: will not terminate for infinite-sized collections.
- returns
- a Traversable containing all elements of this traversable collection.
- Definition Classes
- TraversableLike → TraversableOnce → GenTraversableOnce
- Annotations
- @ deprecatedOverriding (message =…, since = “2.11.0”)
(defined at scala.collection.TraversableLike)
def withFilter(p: ((A, B)) ⇒ Boolean): FilterMonadic[(A, B), HashMap[A, B]]
Creates a non-strict filter of this traversable collection.
Note: the difference between c filter p
and c withFilter p
is that the
former creates a new collection, whereas the latter only restricts the domain of
subsequent map
, flatMap
, foreach
, and withFilter
operations.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- p
- the predicate used to test elements.
- returns
- an object of class
WithFilter
, which supportsmap
,flatMap
,foreach
, andwithFilter
operations. All these operations apply to those elements of this traversable collection which satisfy the predicatep
.
- an object of class
- Definition Classes
- TraversableLike → FilterMonadic
(defined at scala.collection.TraversableLike)
Value Members From scala.collection.TraversableOnce
def /:[B](z: B)(op: (B, (A, B)) ⇒ B): B
Applies a binary operator to a start value and all elements of this traversable or iterator, going left to right.
Note: /:
is alternate syntax for foldLeft
; z /: xs
is the same as
xs foldLeft z
.
Examples:
Note that the folding function used to compute b is equivalent to that used to compute c.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
- B
- the result type of the binary operator.
- z
- the start value.
- op
- the binary operator.
- returns
- the result of inserting
op
between consecutive elements of this traversable or iterator, going left to right with the start valuez
on the left:
- the result of inserting
where `x1, ..., xn` are the elements of this traversable or iterator.
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
def :\[B](z: B)(op: ((A, B), B) ⇒ B): B
Applies a binary operator to all elements of this traversable or iterator and a start value, going right to left.
Note: :\
is alternate syntax for foldRight
; xs :\ z
is the same as
xs foldRight z
.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Examples:
Note that the folding function used to compute b is equivalent to that used to compute c.
- B
- the result type of the binary operator.
- z
- the start value
- op
- the binary operator
- returns
- the result of inserting
op
between consecutive elements of this traversable or iterator, going right to left with the start valuez
on the right:
- the result of inserting
where `x1, ..., xn` are the elements of this traversable or iterator.
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
def addString(b: scala.StringBuilder): scala.StringBuilder
Appends all elements of this traversable or iterator to a string builder. The
written text consists of the string representations (w.r.t. the method
toString
) of all elements of this traversable or iterator without any
separator string.
Example:
- b
- the string builder to which elements are appended.
- returns
- the string builder
b
to which elements were appended.
- the string builder
- Definition Classes
- TraversableOnce
(defined at scala.collection.TraversableOnce)
def addString(b: scala.StringBuilder, sep: String): scala.StringBuilder
Appends all elements of this traversable or iterator to a string builder using a
separator string. The written text consists of the string representations
(w.r.t. the method toString
) of all elements of this traversable or iterator,
separated by the string sep
.
Example:
- b
- the string builder to which elements are appended.
- sep
- the separator string.
- returns
- the string builder
b
to which elements were appended.
- the string builder
- Definition Classes
- TraversableOnce
(defined at scala.collection.TraversableOnce)
def aggregate[B](z: ⇒ B)(seqop: (B, (A, B)) ⇒ B, combop: (B, B) ⇒ B): B
Aggregates the results of applying an operator to subsequent elements.
This is a more general form of fold
and reduce
. It is similar to
foldLeft
in that it doesn’t require the result to be a supertype of the
element type. In addition, it allows parallel collections to be processed in
chunks, and then combines the intermediate results.
aggregate
splits the traversable or iterator into partitions and processes
each partition by sequentially applying seqop
, starting with z
(like
foldLeft
). Those intermediate results are then combined by using combop
(like fold
). The implementation of this operation may operate on an arbitrary
number of collection partitions (even 1), so combop
may be invoked an
arbitrary number of times (even 0).
As an example, consider summing up the integer values of a list of chars. The
initial value for the sum is 0. First, seqop
transforms each input character
to an Int and adds it to the sum (of the partition). Then, combop
just needs
to sum up the intermediate results of the partitions:
- B
- the type of accumulated results
- z
- the initial value for the accumulated result of the partition - this will
typically be the neutral element for the
seqop
operator (e.g.Nil
for list concatenation or0
for summation) and may be evaluated more than once
- the initial value for the accumulated result of the partition - this will
typically be the neutral element for the
- seqop
- an operator used to accumulate results within a partition
- combop
- an associative operator used to combine results from different partitions
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
def collectFirst[B](pf: PartialFunction[(A, B), B]): Option[B]
Finds the first element of the traversable or iterator for which the given partial function is defined, and applies the partial function to it.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- pf
- the partial function
- returns
- an option value containing pf applied to the first value for which it is
defined, or
None
if none exists.
- an option value containing pf applied to the first value for which it is
defined, or
- Definition Classes
- TraversableOnce
Example:
(defined at scala.collection.TraversableOnce)
def copyToArray[B >: (A, B)](xs: Array[B]): Unit
[use case]
Copies the elements of this mutable hash map to an array. Fills the given array
xs
with values of this mutable hash map. Copying will stop once either the
end of the current mutable hash map is reached, or the end of the target array
is reached.
- xs
- the array to fill.
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
def copyToArray[B >: (A, B)](xs: Array[B], start: Int): Unit
[use case]
Copies the elements of this mutable hash map to an array. Fills the given array
xs
with values of this mutable hash map, beginning at index start
. Copying
will stop once either the end of the current mutable hash map is reached, or the
end of the target array is reached.
- xs
- the array to fill.
- start
- the starting index.
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
def copyToBuffer[B >: (A, B)](dest: Buffer[B]): Unit
Copies all elements of this traversable or iterator to a buffer.
Note: will not terminate for infinite-sized collections.
- dest
- The buffer to which elements are copied.
- Definition Classes
- TraversableOnce
(defined at scala.collection.TraversableOnce)
def count(p: ((A, B)) ⇒ Boolean): Int
Counts the number of elements in the traversable or iterator which satisfy a predicate.
- p
- the predicate used to test elements.
- returns
- the number of elements satisfying the predicate
p
.
- the number of elements satisfying the predicate
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
def foldLeft[B](z: B)(op: (B, (A, B)) ⇒ B): B
Applies a binary operator to a start value and all elements of this traversable or iterator, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
- B
- the result type of the binary operator.
- z
- the start value.
- op
- the binary operator.
- returns
- the result of inserting
op
between consecutive elements of this traversable or iterator, going left to right with the start valuez
on the left:
- the result of inserting
where `x1, ..., xn` are the elements of this traversable or iterator.
Returns `z` if this traversable or iterator is empty.
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
def fold[A1 >: (A, B)](z: A1)(op: (A1, A1) ⇒ A1): A1
Folds the elements of this traversable or iterator using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
Note: will not terminate for infinite-sized collections.
- A1
- a type parameter for the binary operator, a supertype of
A
.
- a type parameter for the binary operator, a supertype of
- z
- a neutral element for the fold operation; may be added to the result an
arbitrary number of times, and must not change the result (e.g.,
Nil
for list concatenation, 0 for addition, or 1 for multiplication).
- a neutral element for the fold operation; may be added to the result an
arbitrary number of times, and must not change the result (e.g.,
- op
- a binary operator that must be associative.
- returns
- the result of applying the fold operator
op
between all the elements andz
, orz
if this traversable or iterator is empty.
- the result of applying the fold operator
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
def maxBy[B](f: ((A, B)) ⇒ B)(implicit cmp: Ordering[B]): (A, B)
[use case]
Finds the first element which yields the largest value measured by function f.
- B
- The result type of the function f.
- f
- The measuring function.
- returns
- the first element of this mutable hash map with the largest value measured by function f.
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
def minBy[B](f: ((A, B)) ⇒ B)(implicit cmp: Ordering[B]): (A, B)
[use case]
Finds the first element which yields the smallest value measured by function f.
- B
- The result type of the function f.
- f
- The measuring function.
- returns
- the first element of this mutable hash map with the smallest value measured by function f.
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
def mkString(sep: String): String
Displays all elements of this traversable or iterator in a string using a separator string.
- sep
- the separator string.
- returns
- a string representation of this traversable or iterator. In the resulting
string the string representations (w.r.t. the method
toString
) of all elements of this traversable or iterator are separated by the stringsep
.
- a string representation of this traversable or iterator. In the resulting
string the string representations (w.r.t. the method
- Definition Classes
- TraversableOnce → GenTraversableOnce
Example:
(defined at scala.collection.TraversableOnce)
def mkString(start: String, sep: String, end: String): String
Displays all elements of this traversable or iterator in a string using start, end, and separator strings.
- start
- the starting string.
- sep
- the separator string.
- end
- the ending string.
- returns
- a string representation of this traversable or iterator. The resulting
string begins with the string
start
and ends with the stringend
. Inside, the string representations (w.r.t. the methodtoString
) of all elements of this traversable or iterator are separated by the stringsep
.
- a string representation of this traversable or iterator. The resulting
string begins with the string
- Definition Classes
- TraversableOnce → GenTraversableOnce
Example:
(defined at scala.collection.TraversableOnce)
def reduceLeftOption[B >: (A, B)](op: (B, (A, B)) ⇒ B): Option[B]
Optionally applies a binary operator to all elements of this traversable or iterator, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
- B
- the result type of the binary operator.
- op
- the binary operator.
- returns
- an option value containing the result of
reduceLeft(op)
if this traversable or iterator is nonempty,None
otherwise.
- an option value containing the result of
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
def reduceLeft[B >: (A, B)](op: (B, (A, B)) ⇒ B): B
Applies a binary operator to all elements of this traversable or iterator, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
- B
- the result type of the binary operator.
- op
- the binary operator.
- returns
- the result of inserting
op
between consecutive elements of this traversable or iterator, going left to right:
- the result of inserting
where `x1, ..., xn` are the elements of this traversable or iterator.
- Definition Classes
- TraversableOnce
- Exceptions thrown
- UnsupportedOperationException if this traversable or iterator is empty.
(defined at scala.collection.TraversableOnce)
def reduceOption[A1 >: (A, B)](op: (A1, A1) ⇒ A1): Option[A1]
Reduces the elements of this traversable or iterator, if any, using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
- A1
- A type parameter for the binary operator, a supertype of
A
.
- A type parameter for the binary operator, a supertype of
- op
- A binary operator that must be associative.
- returns
- An option value containing result of applying reduce operator
op
between all the elements if the collection is nonempty, andNone
otherwise.
- An option value containing result of applying reduce operator
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
def reduceRightOption[B >: (A, B)](op: ((A, B), B) ⇒ B): Option[B]
Optionally applies a binary operator to all elements of this traversable or iterator, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
- B
- the result type of the binary operator.
- op
- the binary operator.
- returns
- an option value containing the result of
reduceRight(op)
if this traversable or iterator is nonempty,None
otherwise.
- an option value containing the result of
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
def reduce[A1 >: (A, B)](op: (A1, A1) ⇒ A1): A1
Reduces the elements of this traversable or iterator using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
- A1
- A type parameter for the binary operator, a supertype of
A
.
- A type parameter for the binary operator, a supertype of
- op
- A binary operator that must be associative.
- returns
- The result of applying reduce operator
op
between all the elements if the traversable or iterator is nonempty.
- The result of applying reduce operator
- Definition Classes
- TraversableOnce → GenTraversableOnce
- Exceptions thrown
- UnsupportedOperationException if this traversable or iterator is empty.
(defined at scala.collection.TraversableOnce)
def reversed: List[(A, B)]
- Attributes
- protected[this]
- Definition Classes
- TraversableOnce
(defined at scala.collection.TraversableOnce)
def toIndexedSeq: immutable.IndexedSeq[(A, B)]
Converts this traversable or iterator to an indexed sequence.
Note: will not terminate for infinite-sized collections.
- returns
- an indexed sequence containing all elements of this traversable or iterator.
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
def toList: List[(A, B)]
Converts this traversable or iterator to a list.
Note: will not terminate for infinite-sized collections.
- returns
- a list containing all elements of this traversable or iterator.
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
def toMap[T, U](implicit ev: <:<[(A, B), (T, U)]): immutable.Map[T, U]
[use case]
Converts this mutable hash map to a map. This method is unavailable unless the elements are members of Tuple2, each ((T, U)) becoming a key-value pair in the map. Duplicate keys will be overwritten by later keys: if this is an unordered collection, which key is in the resulting map is undefined.
- returns
- a map of type
immutable.Map[T, U]
containing all key/value pairs of type(T, U)
of this mutable hash map.
- a map of type
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
def toSet[B >: (A, B)]: immutable.Set[B]
Converts this traversable or iterator to a set.
Note: will not terminate for infinite-sized collections.
- returns
- a set containing all elements of this traversable or iterator.
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
def toVector: Vector[(A, B)]
Converts this traversable or iterator to a Vector.
Note: will not terminate for infinite-sized collections.
- returns
- a vector containing all elements of this traversable or iterator.
- Definition Classes
- TraversableOnce → GenTraversableOnce
(defined at scala.collection.TraversableOnce)
Value Members From scala.collection.generic.GenericTraversableTemplate
def flatten[B](implicit asTraversable: ((A, B)) ⇒ GenTraversableOnce[B]): Iterable[B]
[use case]
Converts this mutable hash map of traversable collections into a mutable hash map formed by the elements of these traversable collections.
The resulting collection’s type will be guided by the static type of mutable hash map. For example:
- B
- the type of the elements of each traversable collection.
- returns
- a new mutable hash map resulting from concatenating all element mutable hash maps.
- Definition Classes
- GenericTraversableTemplate
(defined at scala.collection.generic.GenericTraversableTemplate)
def genericBuilder[B]: Builder[B, Iterable[B]]
The generic builder that builds instances of Traversable at arbitrary element types.
- Definition Classes
- GenericTraversableTemplate
(defined at scala.collection.generic.GenericTraversableTemplate)
def transpose[B](implicit asTraversable: ((A, B)) ⇒ GenTraversableOnce[B]): Iterable[Iterable[B]]
Transposes this collection of traversable collections into a collection of collections.
The resulting collection’s type will be guided by the static type of collection. For example:
- B
- the type of the elements of each traversable collection.
- asTraversable
- an implicit conversion which asserts that the element type of this
collection is a
Traversable
.
- an implicit conversion which asserts that the element type of this
collection is a
- returns
- a two-dimensional collection of collections which has as n th row the n th column of this collection.
- Definition Classes
- GenericTraversableTemplate
- Annotations
- @migration
- Migration
- (Changed in version 2.9.0)
transpose
throws anIllegalArgumentException
if collections are not uniformly sized.
- (Changed in version 2.9.0)
- Exceptions thrown
- IllegalArgumentException if all collections in this collection are not of the same size.
(defined at scala.collection.generic.GenericTraversableTemplate)
def unzip3[A1, A2, A3](implicit asTriple: ((A, B)) ⇒ (A1, A2, A3)): (Iterable[A1], Iterable[A2], Iterable[A3])
Converts this collection of triples into three collections of the first, second, and third element of each triple.
- A1
- the type of the first member of the element triples
- A2
- the type of the second member of the element triples
- A3
- the type of the third member of the element triples
- asTriple
- an implicit conversion which asserts that the element type of this collection is a triple.
- returns
- a triple of collections, containing the first, second, respectively third member of each element triple of this collection.
- Definition Classes
- GenericTraversableTemplate
(defined at scala.collection.generic.GenericTraversableTemplate)
def unzip[A1, A2](implicit asPair: ((A, B)) ⇒ (A1, A2)): (Iterable[A1], Iterable[A2])
Converts this collection of pairs into two collections of the first and second half of each pair.
- A1
- the type of the first half of the element pairs
- A2
- the type of the second half of the element pairs
- asPair
- an implicit conversion which asserts that the element type of this collection is a pair.
- returns
- a pair of collections, containing the first, respectively second half of each element pair of this collection.
- Definition Classes
- GenericTraversableTemplate
(defined at scala.collection.generic.GenericTraversableTemplate)
Value Members From scala.collection.generic.Growable
def ++=(xs: TraversableOnce[(A, B)]): HashMap.this.type
adds all elements produced by a TraversableOnce to this growable collection.
- xs
- the TraversableOnce producing the elements to add.
- returns
- the growable collection itself.
- Definition Classes
- Growable
(defined at scala.collection.generic.Growable)
def +=(elem1: (A, B), elem2: (A, B), elems: (A, B)*): HashMap.this.type
adds two or more elements to this growable collection.
- elem1
- the first element to add.
- elem2
- the second element to add.
- elems
- the remaining elements to add.
- returns
- the growable collection itself
- Definition Classes
- Growable
(defined at scala.collection.generic.Growable)
Value Members From scala.collection.generic.Shrinkable
def --=(xs: TraversableOnce[A]): HashMap.this.type
Removes all elements produced by an iterator from this shrinkable collection.
- xs
- the iterator producing the elements to remove.
- returns
- the shrinkable collection itself
- Definition Classes
- Shrinkable
(defined at scala.collection.generic.Shrinkable)
def -=(elem1: A, elem2: A, elems: A*): HashMap.this.type
Removes two or more elements from this shrinkable collection.
- elem1
- the first element to remove.
- elem2
- the second element to remove.
- elems
- the remaining elements to remove.
- returns
- the shrinkable collection itself
- Definition Classes
- Shrinkable
(defined at scala.collection.generic.Shrinkable)
Value Members From scala.collection.mutable.Builder
def mapResult[NewTo](f: (HashMap[A, B]) ⇒ NewTo): Builder[(A, B), NewTo]
Creates a new builder by applying a transformation function to the results of this builder.
- NewTo
- the type of collection returned by
f
.
- the type of collection returned by
- f
- the transformation function.
- returns
- a new builder which is the same as the current builder except that a transformation function is applied to this builder’s result.
- Definition Classes
- Builder
- Note
- The original builder should no longer be used after
mapResult
is called.
- The original builder should no longer be used after
(defined at scala.collection.mutable.Builder)
def sizeHint(size: Int): Unit
Gives a hint how many elements are expected to be added when the next result
is called. Some builder classes will optimize their representation based on the
hint. However, builder implementations are still required to work correctly even
if the hint is wrong, i.e. a different number of elements is added.
- size
- the hint how many elements will be added.
- Definition Classes
- Builder
(defined at scala.collection.mutable.Builder)
def sizeHint(coll: TraversableLike[_, _]): Unit
Gives a hint that one expects the result
of this builder to have the same size
as the given collection, plus some delta. This will provide a hint only if the
collection is known to have a cheap size
method. Currently this is assumed to
be the case if and only if the collection is of type IndexedSeqLike
. Some
builder classes will optimize their representation based on the hint. However,
builder implementations are still required to work correctly even if the hint is
wrong, i.e. a different number of elements is added.
- coll
- the collection which serves as a hint for the result’s size.
- Definition Classes
- Builder
(defined at scala.collection.mutable.Builder)
def sizeHint(coll: TraversableLike[_, _], delta: Int): Unit
Gives a hint that one expects the result
of this builder to have the same size
as the given collection, plus some delta. This will provide a hint only if the
collection is known to have a cheap size
method. Currently this is assumed to
be the case if and only if the collection is of type IndexedSeqLike
. Some
builder classes will optimize their representation based on the hint. However,
builder implementations are still required to work correctly even if the hint is
wrong, i.e. a different number of elements is added.
- coll
- the collection which serves as a hint for the result’s size.
- delta
- a correction to add to the
coll.size
to produce the size hint.
- a correction to add to the
- Definition Classes
- Builder
(defined at scala.collection.mutable.Builder)
def sizeHintBounded(size: Int, boundingColl: TraversableLike[_, _]): Unit
Gives a hint how many elements are expected to be added when the next result
is called, together with an upper bound given by the size of some other
collection. Some builder classes will optimize their representation based on the
hint. However, builder implementations are still required to work correctly even
if the hint is wrong, i.e. a different number of elements is added.
- size
- the hint how many elements will be added.
- boundingColl
- the bounding collection. If it is an IndexedSeqLike, then sizes larger than collection’s size are reduced.
- Definition Classes
- Builder
(defined at scala.collection.mutable.Builder)
Instance Constructors From scala.collection.mutable.HashMap
new HashMap()
(defined at scala.collection.mutable.HashMap)
Value Members From scala.collection.mutable.HashMap
def +=(kv: (A, B)): HashMap.this.type
Adds a new key/value pair to this map. If the map already contains a mapping for the key, it will be overridden by the new value.
- kv
- the key/value pair.
- returns
- the map itself
- Definition Classes
- HashMap → MapLike → Builder → Growable
(defined at scala.collection.mutable.HashMap)
def -=(key: A): HashMap.this.type
Removes a key from this map.
- key
- the key to be removed
- returns
- the map itself.
- Definition Classes
- HashMap → MapLike → Shrinkable
(defined at scala.collection.mutable.HashMap)
def apply(key: A): B
Retrieves the value which is associated with the given key. This method invokes
the default
method of the map if there is no mapping from the given key to a
value. Unless overridden, the default
method throws a
NoSuchElementException
.
- key
- the key
- returns
- the value associated with the given key, or the result of the map’s
default
method, if none exists.
- the value associated with the given key, or the result of the map’s
- Definition Classes
- HashMap → MapLike → Function1 → GenMapLike
(defined at scala.collection.mutable.HashMap)
def contains(key: A): Boolean
Tests whether this map contains a binding for a key.
- key
- the key
- returns
true
if there is a binding forkey
in this map,false
otherwise.
- Definition Classes
- HashMap → MapLike → GenMapLike
(defined at scala.collection.mutable.HashMap)
def createNewEntry[B1](key: A, value: B1): Entry
Creates new entry to be immediately inserted into the hashtable. This method is guaranteed to be called only once and in case that the entry will be added. In other words, an implementation may be side-effecting.
- Attributes
- protected
- Definition Classes
- HashMap → HashTable
(defined at scala.collection.mutable.HashMap)
def empty: HashMap[A, B]
The empty map of the same type as this map
- returns
- an empty map of type
This
.
- an empty map of type
- Definition Classes
- HashMap → Map → Map → MapLike
(defined at scala.collection.mutable.HashMap)
def foreach[U](f: ((A, B)) ⇒ U): Unit
[use case]
Applies a function f
to all elements of this mutable hash map.
Note: this method underlies the implementation of most other bulk operations. Subclasses should re-implement this method if a more efficient implementation exists.
- f
- the function that is applied for its side-effect to every element. The
result of function
f
is discarded.
- the function that is applied for its side-effect to every element. The
result of function
- Definition Classes
- HashMap → IterableLike → GenericTraversableTemplate → TraversableLike → GenTraversableLike → TraversableOnce → GenTraversableOnce → FilterMonadic
(defined at scala.collection.mutable.HashMap)
def get(key: A): Option[B]
Optionally returns the value associated with a key.
- key
- the key value
- returns
- an option value containing the value associated with
key
in this map, orNone
if none exists.
- an option value containing the value associated with
- Definition Classes
- HashMap → MapLike → GenMapLike
(defined at scala.collection.mutable.HashMap)
def keySet: collection.Set[A]
Collects all keys of this map in a set.
- returns
- a set containing all keys of this map.
- Definition Classes
- HashMap → MapLike → GenMapLike
(defined at scala.collection.mutable.HashMap)
def par: ParHashMap[A, B]
Returns a parallel implementation of this collection.
For most collection types, this method creates a new parallel collection by
copying all the elements. For these collection, par
takes linear time. Mutable
collections in this category do not produce a mutable parallel collection that
has the same underlying dataset, so changes in one collection will not be
reflected in the other one.
Specific collections (e.g. ParArray
or mutable.ParHashMap
) override this
default behaviour by creating a parallel collection which shares the same
underlying dataset. For these collections, par
takes constant or sublinear
time.
All parallel collections return a reference to themselves.
- returns
- a parallel implementation of this collection
- Definition Classes
- HashMap → CustomParallelizable → Parallelizable
(defined at scala.collection.mutable.HashMap)
def put(key: A, value: B): Option[B]
Adds a new key/value pair to this map and optionally returns previously bound value. If the map already contains a mapping for the key, it will be overridden by the new value.
- key
- the key to update
- value
- the new value
- returns
- an option value containing the value associated with the key before the
put
operation was executed, orNone
ifkey
was not defined in the map before.
- an option value containing the value associated with the key before the
- Definition Classes
- HashMap → MapLike
(defined at scala.collection.mutable.HashMap)
def remove(key: A): Option[B]
Removes a key from this map, returning the value associated previously with that key as an option.
- key
- the key to be removed
- returns
- an option value containing the value associated previously with
key
, orNone
ifkey
was not defined in the map before.
- an option value containing the value associated previously with
- Definition Classes
- HashMap → MapLike
(defined at scala.collection.mutable.HashMap)
def update(key: A, value: B): Unit
Adds a new key/value pair to this map. If the map already contains a mapping for the key, it will be overridden by the new value.
- key
- The key to update
- value
- The new value
- Definition Classes
- HashMap → MapLike
(defined at scala.collection.mutable.HashMap)
def useSizeMap(t: Boolean): Unit
Toggles whether a size map is used to track hash map statistics.
(defined at scala.collection.mutable.HashMap)
def values: collection.Iterable[B]
Collects all values of this map in an iterable collection.
- returns
- the values of this map as an iterable.
- Definition Classes
- HashMap → MapLike → GenMapLike
(defined at scala.collection.mutable.HashMap)
Value Members From scala.collection.mutable.HashTable
def addEntry(e: DefaultEntry[A, B]): Unit
Add entry to table pre: no entry with same key exists
- Attributes
- protected
- Definition Classes
- HashTable
- Annotations
- @ deprecatedOverriding (message =…, since = “2.11.0”)
(defined at scala.collection.mutable.HashTable)
def calcSizeMapSize(tableLength: Int): Int
- Attributes
- protected
- Definition Classes
- HashTable
- Annotations
- @ deprecatedOverriding (message =…, since = “2.11.0”)
(defined at scala.collection.mutable.HashTable)
def elemEquals(key1: A, key2: A): Boolean
- Attributes
- protected
- Definition Classes
- HashTable
(defined at scala.collection.mutable.HashTable)
def entriesIterator: Iterator[DefaultEntry[A, B]]
An iterator returning all entries.
- Attributes
- protected
- Definition Classes
- HashTable
(defined at scala.collection.mutable.HashTable)
def findEntry(key: A): DefaultEntry[A, B]
Find entry with given key in table, null if not found.
- Attributes
- protected
- Definition Classes
- HashTable
- Annotations
- @ deprecatedOverriding (message =…, since = “2.11.0”)
(defined at scala.collection.mutable.HashTable)
def findOrAddEntry[B](key: A, value: B): DefaultEntry[A, B]
Find entry with given key in table, or add new one if not found. May be somewhat
faster then findEntry
/ addEntry
pair as it computes entry’s hash index only
once. Returns entry found in table or null. New entries are created by calling
createNewEntry
method.
- Attributes
- protected
- Definition Classes
- HashTable
(defined at scala.collection.mutable.HashTable)
def foreachEntry[U](f: (DefaultEntry[A, B]) ⇒ U): Unit
Avoid iterator for a 2x faster traversal.
- Attributes
- protected
- Definition Classes
- HashTable
(defined at scala.collection.mutable.HashTable)
final def index(hcode: Int): Int
- Attributes
- protected
- Definition Classes
- HashTable
(defined at scala.collection.mutable.HashTable)
def initWithContents(c: Contents[A, DefaultEntry[A, B]]): Unit
- Attributes
- protected
- Definition Classes
- HashTable
(defined at scala.collection.mutable.HashTable)
def nnSizeMapAdd(h: Int): Unit
- Attributes
- protected
- Definition Classes
- HashTable
- Annotations
- @ deprecatedOverriding (message =…, since = “2.11.0”)
(defined at scala.collection.mutable.HashTable)
def nnSizeMapRemove(h: Int): Unit
- Attributes
- protected
- Definition Classes
- HashTable
- Annotations
- @ deprecatedOverriding (message =…, since = “2.11.0”)
(defined at scala.collection.mutable.HashTable)
def nnSizeMapReset(tableLength: Int): Unit
- Attributes
- protected
- Definition Classes
- HashTable
- Annotations
- @ deprecatedOverriding (message =…, since = “2.11.0”)
(defined at scala.collection.mutable.HashTable)
def removeEntry(key: A): DefaultEntry[A, B]
Remove entry from table if present.
- Attributes
- protected
- Definition Classes
- HashTable
- Annotations
- @ deprecatedOverriding (message =…, since = “2.11.0”)
(defined at scala.collection.mutable.HashTable)
def sizeMapInit(tableLength: Int): Unit
- Attributes
- protected
- Definition Classes
- HashTable
(defined at scala.collection.mutable.HashTable)
var table: Array[HashEntry[A, DefaultEntry[A, B]]]
The actual hash table.
- Attributes
- protected
- Definition Classes
- HashTable
(defined at scala.collection.mutable.HashTable)
Value Members From scala.collection.mutable.HashTable.HashUtils
def elemHashCode(key: A): Int
- Attributes
- protected
- Definition Classes
- HashUtils
(defined at scala.collection.mutable.HashTable.HashUtils)
final def improve(hcode: Int, seed: Int): Int
- Attributes
- protected
- Definition Classes
- HashUtils
(defined at scala.collection.mutable.HashTable.HashUtils)
Value Members From scala.collection.mutable.Iterable
def companion: GenericCompanion[Iterable]
The factory companion object that builds instances of class Iterable. (or its
Iterable
superclass where class Iterable is not a Seq
.)
- Definition Classes
- Iterable → Iterable → GenIterable → Traversable → Traversable → GenTraversable → GenericTraversableTemplate
(defined at scala.collection.mutable.Iterable)
Value Members From scala.collection.mutable.Map
def seq: Map[A, B]
A version of this collection with all of the operations implemented sequentially (i.e., in a single-threaded manner).
This method returns a reference to this collection. In parallel collections, it is redefined to return a sequential implementation of this collection. In both cases, it has O(1) complexity.
- returns
- a sequential view of the collection.
- Definition Classes
- Map → Map → GenMap → GenMapLike → Iterable → Iterable → GenIterable → Traversable → Traversable → GenTraversable → Parallelizable → TraversableOnce → GenTraversableOnce
(defined at scala.collection.mutable.Map)
def withDefault(d: (A) ⇒ B): Map[A, B]
The same map with a given default function.
Invoking transformer methods (e.g. map
) will not preserve the default value.
- d
- the function mapping keys to values, used for non-present keys
- returns
- a wrapper of the map with a default value
- Definition Classes
- Map
(defined at scala.collection.mutable.Map)
def withDefaultValue(d: B): Map[A, B]
The same map with a given default value.
Invoking transformer methods (e.g. map
) will not preserve the default value.
- d
- default value used for non-present keys
- returns
- a wrapper of the map with a default value
- Definition Classes
- Map
(defined at scala.collection.mutable.Map)
Value Members From scala.collection.mutable.MapLike
def ++[B1 >: B](xs: GenTraversableOnce[(A, B1)]): Map[A, B1]
Creates a new map containing the key/value mappings provided by the specified traversable object and all the key/value mappings of this map.
Note that existing mappings from this map with the same key as those in xs
will be overridden.
- B1
- the type of the added values
- xs
- the traversable object.
- returns
- a new map containing mappings of this map and those provided by
xs
.
- a new map containing mappings of this map and those provided by
- Definition Classes
- MapLike → MapLike
- Annotations
- @migration
- Migration
- (Changed in version 2.8.0)
++
creates a new map. Use++=
to add an element to this map and return that map itself.
- (Changed in version 2.8.0)
(defined at scala.collection.mutable.MapLike)
def +[B1 >: B](kv: (A, B1)): Map[A, B1]
Creates a new map containing a new key/value mapping and all the key/value mappings of this map.
Mapping kv
will override existing mappings from this map with the same key.
- B1
- the type of the value in the key/value pair.
- kv
- the key/value mapping to be added
- returns
- a new map containing mappings of this map and the mapping
kv
.
- a new map containing mappings of this map and the mapping
- Definition Classes
- MapLike → MapLike → GenMapLike
- Annotations
- @migration
- Migration
- (Changed in version 2.8.0)
+
creates a new map. Use+=
to add an element to this map and return that map itself.
- (Changed in version 2.8.0)
(defined at scala.collection.mutable.MapLike)
def +[B1 >: B](elem1: (A, B1), elem2: (A, B1), elems: (A, B1)*): Map[A, B1]
Creates a new map containing two or more key/value mappings and all the key/value mappings of this map.
Specified mappings will override existing mappings from this map with the same keys.
- B1
- the type of the added values
- elem1
- the first element to add.
- elem2
- the second element to add.
- elems
- the remaining elements to add.
- returns
- a new map containing mappings of this map and two or more specified mappings.
- Definition Classes
- MapLike → MapLike
- Annotations
- @migration
- Migration
- (Changed in version 2.8.0)
+
creates a new map. Use+=
to add an element to this map and return that map itself.
- (Changed in version 2.8.0)
(defined at scala.collection.mutable.MapLike)
def -(key: A): HashMap[A, B]
Creates a new map with all the key/value mappings of this map except the key/value mapping with the specified key.
- key
- the key to be removed
- returns
- a new map with all the mappings of this map except that with a key
key
.
- a new map with all the mappings of this map except that with a key
- Definition Classes
- MapLike → MapLike → Subtractable → GenMapLike
- Annotations
- @migration
- Migration
- (Changed in version 2.8.0)
-
creates a new map. Use-=
to remove an element from this map and return that map itself.
- (Changed in version 2.8.0)
(defined at scala.collection.mutable.MapLike)
def -(elem1: A, elem2: A, elems: A*): HashMap[A, B]
Creates a new map with all the key/value mappings of this map except mappings with keys equal to any of the two or more specified keys.
- elem1
- the first element to remove.
- elem2
- the second element to remove.
- elems
- the remaining elements to remove.
- returns
- a new map containing all the mappings of this map except mappings with a key
equal to
elem1
,elem2
or any ofelems
.
- a new map containing all the mappings of this map except mappings with a key
equal to
- Definition Classes
- MapLike → Subtractable
- Annotations
- @migration
- Migration
- (Changed in version 2.8.0)
-
creates a new map. Use-=
to remove an element from this map and return that map itself.
- (Changed in version 2.8.0)
(defined at scala.collection.mutable.MapLike)
def --(xs: GenTraversableOnce[A]): HashMap[A, B]
Creates a new map with all the key/value mappings of this map except mappings with keys equal to any of those provided by the specified traversable object.
- xs
- the traversable object.
- returns
- a new map with all the key/value mappings of this map except mappings with a
key equal to a key from
xs
.
- a new map with all the key/value mappings of this map except mappings with a
key equal to a key from
- Definition Classes
- MapLike → Subtractable
- Annotations
- @migration
- Migration
- (Changed in version 2.8.0)
--
creates a new map. Use--=
to remove an element from this map and return that map itself.
- (Changed in version 2.8.0)
(defined at scala.collection.mutable.MapLike)
def clone(): HashMap[A, B]
Create a copy of the receiver object.
The default implementation of the clone
method is platform dependent.
- returns
- a copy of the receiver object.
- Definition Classes
- MapLike → Cloneable → AnyRef
- Note
- not specified by SLS as a member of AnyRef
(defined at scala.collection.mutable.MapLike)
def getOrElseUpdate(key: A, op: ⇒ B): B
If given key is already in this map, returns associated value.
Otherwise, computes value from given expression op
, stores with key in map
and returns that value.
Concurrent map implementations may evaluate the expression op
multiple times,
or may evaluate op
without inserting the result.
- key
- the key to test
- op
- the computation yielding the value to associate with
key
, ifkey
is previously unbound.
- the computation yielding the value to associate with
- returns
- the value associated with key (either previously or as a result of executing the method).
- Definition Classes
- MapLike
(defined at scala.collection.mutable.MapLike)
def newBuilder: Builder[(A, B), HashMap[A, B]]
A common implementation of newBuilder
for all mutable maps in terms of
empty
.
Overrides MapLike
implementation for better efficiency.
- Attributes
- protected[this]
- Definition Classes
- MapLike → MapLike → TraversableLike → HasNewBuilder
(defined at scala.collection.mutable.MapLike)
def result(): HashMap[A, B]
The result when this map is used as a builder
- returns
- the map representation itself.
- Definition Classes
- MapLike → Builder
(defined at scala.collection.mutable.MapLike)
def retain(p: (A, B) ⇒ Boolean): HashMap.this.type
Retains only those mappings for which the predicate p
returns true
.
- p
- The test predicate
- Definition Classes
- MapLike
(defined at scala.collection.mutable.MapLike)
def toSeq: collection.Seq[(A, B)]
Converts this mutable map to a sequence.
Note
: assumes a fast size
method. Subclasses should override if this is
not true.
- returns
- a sequence containing all elements of this mutable map.
- Definition Classes
- MapLike → MapLike → TraversableOnce → GenTraversableOnce
(defined at scala.collection.mutable.MapLike)
def transform(f: (A, B) ⇒ B): HashMap.this.type
Applies a transformation function to all values contained in this map. The transformation function produces new values from existing keys associated values.
- f
- the transformation to apply
- returns
- the map itself.
- Definition Classes
- MapLike
(defined at scala.collection.mutable.MapLike)
def updated[B1 >: B](key: A, value: B1): Map[A, B1]
Creates a new map consisting of all key/value pairs of the current map plus a new pair of a given key and value.
- B1
- the type of the added value
- key
- The key to add
- value
- The new value
- returns
- A fresh immutable map with the binding from
key
tovalue
added to this map.
- A fresh immutable map with the binding from
- Definition Classes
- MapLike → MapLike
(defined at scala.collection.mutable.MapLike)
Value Members From Implicit scala.collection.parallel.CollectionsHaveToParArray ——————————————————————————–
def toParArray: ParArray[T]
- Implicit information
- This member is added by an implicit conversion from HashMap [A, B] to CollectionsHaveToParArray [HashMap [A, B], T] performed by method CollectionsHaveToParArray in scala.collection.parallel. This conversion will take place only if an implicit value of type (HashMap [A, B]) ⇒ GenTraversableOnce [T] is in scope.
- Definition Classes
- CollectionsHaveToParArray (added by implicit convertion: scala.collection.parallel.CollectionsHaveToParArray)
Full Source:
Interested in Scala?
I send out weekly, personalized emails with articles and conference talks.
Subscribe now.