Class scala.collection.mutable.HashSet

Companion object • Source code



final class HashSet[A](initialCapacity: Int, loadFactor: Double) extends AbstractSet[A] with SetOps[A, HashSet, HashSet[A]] with StrictOptimizedIterableOps[A, HashSet, HashSet[A]] with IterableFactoryDefaults[A, HashSet] with Serializable


This class implements mutable sets using a hashtable. 


See also
"Scala's Collection Library overview" section on Hash Tables for more information.


Supertypes

26 types

trait Serializable

trait StrictOptimizedIterableOps[A, HashSet, HashSet[A]]
class AbstractSet[A]
trait Set[A]
trait SetOps[A, HashSet, HashSet[A]]
trait Shrinkable[A]
trait Builder[A, HashSet[A]]
trait Growable[A]
trait Clearable

trait Cloneable[HashSet[A]]
trait Cloneable

trait Iterable[A]
class AbstractSet[A]
trait Set[A]
trait Equals

trait SetOps[A, HashSet, HashSet[A]]
trait A => Boolean

class AbstractIterable[A]
trait Iterable[A]
trait IterableFactoryDefaults[A, HashSet]
trait IterableOps[A, HashSet, HashSet[A]]
trait IterableOnceOps[A, HashSet, HashSet[A]]
trait IterableOnce[A]
class Object

trait Matchable

class Any





Constructors

Source
def this()


Concrete methods

Source
override def add(elem: A): Boolean



Definition Classes
SetOps


Source
override def addAll(xs: IterableOnce[A]): HashSet[A]



Definition Classes
Growable


Source@inline 
def addOne(elem: A): HashSet[A]



Source
def clear(): Unit



Source
override def contains(elem: A): Boolean



Definition Classes
SetOps


Source
override def filterInPlace(p: A => Boolean): HashSet[A]



Definition Classes
SetOps


Source
override def foreach[U](f: A => U): Unit



Definition Classes
IterableOnceOps


Source
override def hashCode: Int



Definition Classes

Set -> Any



Source
override def isEmpty: Boolean



Definition Classes
IterableOnceOps


Source
override def iterableFactory: IterableFactory[HashSet]



Definition Classes

Set -> Iterable -> Set -> Iterable -> IterableOps



Source
override def iterator: Iterator[A]



Definition Classes
IterableOnce


Source
override def knownSize: Int



Definition Classes

SetOps -> Growable -> IterableOnce



Source
override def remove(elem: A): Boolean



Definition Classes
SetOps


Source
override def size: Int



Definition Classes
IterableOnceOps


Source
override def sizeHint(size: Int): Unit



Definition Classes
Builder


Source
override def stepper[S <: Stepper[_]](implicit shape: StepperShape[A, S]): S & EfficientSplit



Definition Classes
IterableOnce


Source
override def subtractAll(xs: IterableOnce[A]): HashSet[A]



Definition Classes
Shrinkable


Source@inline 
def subtractOne(elem: A): HashSet[A]


Inherited methods

Source@inline 
final def &(that: Set[A]): HashSet[A]


Alias for intersect

Inherited from
SetOps


Source@inline 
final def &~(that: Set[A]): HashSet[A]


Alias for diff

Inherited from
SetOps


Source@inline 
final def ++[B >: A](suffix: IterableOnce[B]): HashSet[B]


Alias for concat

Inherited from
IterableOps


Source@inline 
final def ++(that: IterableOnce[A]): HashSet[A]


Alias for concat

Inherited from
SetOps


Source@inline 
final def ++=(xs: IterableOnce[A]): HashSet[A]


Alias for addAll

Inherited from
Growable


Source@inline 
final def +=(elem: A): HashSet[A]


Alias for addOne

Inherited from
Growable


Source@inline 
final def --=(xs: IterableOnce[A]): HashSet[A]


Alias for subtractAll

Inherited from
Shrinkable


Source@inline 
final def -=(elem: A): HashSet[A]


Alias for subtractOne

Inherited from
Shrinkable


Source@inline 
final def addString(b: StringBuilder): StringBuilder


Appends all elements of this collection to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this collection without any separator string.
Example:
scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> val h = a.addString(b)
h: StringBuilder = 1234


Value parameters

b
the string builder to which elements are appended.



Returns
the string builder b to which elements were appended.


Inherited from
IterableOnceOps



Source@inline 
final def addString(b: StringBuilder, sep: String): StringBuilder


Appends all elements of this collection 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 collection, separated by the string sep.
Example:
scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> a.addString(b, ", ")
res0: StringBuilder = 1, 2, 3, 4


Value parameters

b
the string builder to which elements are appended.
sep
the separator string.



Returns
the string builder b to which elements were appended.


Inherited from
IterableOnceOps



Source
def addString(b: StringBuilder, start: String, sep: String, end: String): StringBuilder


Appends all elements of this collection 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 (w.r.t. the method toString) of all elements of this collection are separated by the string sep.
Example:
scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> a.addString(b , "List(" , ", " , ")")
res5: StringBuilder = List(1, 2, 3, 4)


Value parameters

b
the string builder to which elements are appended.
end
the ending string.
sep
the separator string.
start
the starting string.



Returns
the string builder b to which elements were appended.


Inherited from
IterableOnceOps



Source@unspecialized 
def andThen[A](g: Boolean => A): A => A


Composes two instances of Function1 in a new Function1, with this function applied first. 


Type parameters

A
the result type of function g



Value parameters

g
a function R => A



Returns
a new function f such that f(x) == g(apply(x))


Inherited from
Function1



Source@inline 
final def apply(elem: A): Boolean


Tests if some element is contained in this set.
This method is equivalent to contains. It allows sets to be interpreted as predicates.


Value parameters

elem
the element to test for membership.



Returns
true if elem is contained in this set, false otherwise.


Inherited from
SetOps



Source
def canEqual(that: Any): Boolean



Inherited from
Set


Source
override def clone(): HashSet[A]




Definition Classes

SetOps -> Cloneable -> Object



Inherited from
SetOps



Source
override def collect[B](pf: PartialFunction[A, B]): HashSet[B]




Definition Classes

StrictOptimizedIterableOps -> IterableOps -> IterableOnceOps



Inherited from
StrictOptimizedIterableOps



Source
def collectFirst[B](pf: PartialFunction[A, B]): Option[B]


Finds the first element of the collection 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. 


Value parameters

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.


Example
Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)


Inherited from
IterableOnceOps



Source@unspecialized 
def compose[A](g: A => A): A => Boolean


Composes two instances of Function1 in a new Function1, with this function applied last. 


Type parameters

A
the type to which function g can be applied



Value parameters

g
a function A => T1



Returns
a new function f such that f(x) == apply(g(x))


Inherited from
Function1



Source
def concat[B >: A](suffix: IterableOnce[B]): HashSet[B]


Returns a new iterable collection containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the iterable collection is the most specific superclass encompassing the element types of the two operands. 


Type parameters

B
the element type of the returned collection.



Value parameters

suffix
the traversable to append.



Returns
a new iterable collection which contains all elements of this iterable collection followed by all elements of suffix.


Inherited from
IterableOps



Source
def concat(that: IterableOnce[A]): HashSet[A]


Creates a new set by adding all elements contained in another collection to this set, omitting duplicates.
This method takes a collection of elements and adds all elements, omitting duplicates, into set.
Example:
scala> val a = Set(1, 2) concat Set(2, 3)
a: scala.collection.immutable.Set[Int] = Set(1, 2, 3)


Value parameters

that
the collection containing the elements to add.



Returns
a new set with the given elements added, omitting duplicates.


Inherited from
SetOps



Source
def copyToArray[B >: A](xs: Array[B], start: Int, len: Int): Int


Copy elements to an array, returning the number of elements written.
Fills the given array xs starting at index start with at most len elements of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached, or len elements have been copied. 


Type parameters

B
the type of the elements of the array.



Value parameters

len
the maximal number of elements to copy.
start
the starting index of xs.
xs
the array to fill.



Returns
the number of elements written to the array


Note
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.


Inherited from
IterableOnceOps



Source@deprecatedOverriding("This should always forward to the 3-arg version of this method", since = "2.13.4") 
def copyToArray[B >: A](xs: Array[B], start: Int): Int


Copy elements to an array, returning the number of elements written.
Fills the given array xs starting at index start with values of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached. 


Type parameters

B
the type of the elements of the array.



Value parameters

start
the starting index of xs.
xs
the array to fill.



Returns
the number of elements written to the array


Note
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.


Inherited from
IterableOnceOps



Source@deprecatedOverriding("This should always forward to the 3-arg version of this method", since = "2.13.4") 
def copyToArray[B >: A](xs: Array[B]): Int


Copy elements to an array, returning the number of elements written.
Fills the given array xs starting at index start with values of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached. 


Type parameters

B
the type of the elements of the array.



Value parameters

xs
the array to fill.



Returns
the number of elements written to the array


Note
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.


Inherited from
IterableOnceOps



Source
def corresponds[B](that: IterableOnce[B])(p: (A, B) => Boolean): Boolean


Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.
 Note: will not terminate for infinite-sized collections. 


Type parameters

B
the type of the elements of that



Value parameters

p
the test predicate, which relates elements from both collections
that
the other collection



Returns
true if both collections have the same length and p(x, y) is true for all corresponding elements x of this iterator and y of that, otherwise false


Inherited from
IterableOnceOps



Source
def count(p: A => Boolean): Int


Counts the number of elements in the collection which satisfy a predicate.
 Note: will not terminate for infinite-sized collections. 


Value parameters

p
the predicate used to test elements.



Returns
the number of elements satisfying the predicate p.


Inherited from
IterableOnceOps



Source
def diff(that: Set[A]): HashSet[A]



Inherited from
SetOps


Source
def drop(n: Int): HashSet[A]



Inherited from
IterableOps


Source
override def dropRight(n: Int): HashSet[A]


The rest of the collection without its n last elements. For linear, immutable collections this should avoid making a copy.
 Note: Even when applied to a view or a lazy collection it will always force the elements. 


Definition Classes

StrictOptimizedIterableOps -> IterableOps



Inherited from
StrictOptimizedIterableOps



Source
def dropWhile(p: A => Boolean): HashSet[A]



Inherited from
IterableOps


Source
override def empty: HashSet[A]




Definition Classes

IterableFactoryDefaults -> IterableOps



Inherited from
IterableFactoryDefaults



Source
override def equals(that: Any): Boolean


Equality of sets is implemented using the lookup method contains. This method returns true if

the argument that is a Set,
the two sets have the same size, and
for every element this set, other.contains(element) == true.

The implementation of equals checks the canEqual method, so subclasses of Set can narrow down the equality to specific set types. The Set implementations in the standard library can all be compared, their canEqual methods return true.
Note: The equals method only respects the equality laws (symmetry, transitivity) if the two sets use the same element equivalence function in their lookup operation. For example, the element equivalence operation in a scala.collection.immutable.TreeSet is defined by its ordering. Comparing a TreeSet with a HashSet leads to unexpected results if ordering.equiv(e1, e2) (used for lookup in TreeSet) is different from e1 == e2 (used for lookup in HashSet).
scala> import scala.collection.immutable._
scala> val ord: Ordering[String] = _ compareToIgnoreCase _

scala> TreeSet("A")(ord) == HashSet("a")
val res0: Boolean = false

scala> HashSet("a") == TreeSet("A")(ord)
val res1: Boolean = true


Value parameters

that
The set to which this set is compared



Returns
true if the two sets are equal according to the description


Definition Classes

Set -> Equals -> Any



Inherited from
Set



Source
def exists(p: A => Boolean): Boolean


Tests whether a predicate holds for at least one element of this collection.
 Note: may not terminate for infinite-sized collections. 


Value parameters

p
the predicate used to test elements.



Returns
true if the given predicate p is satisfied by at least one element of this collection, otherwise false


Inherited from
IterableOnceOps



Source
override def filter(pred: A => Boolean): HashSet[A]




Definition Classes

StrictOptimizedIterableOps -> IterableOps -> IterableOnceOps



Inherited from
StrictOptimizedIterableOps



Source
override def filterNot(pred: A => Boolean): HashSet[A]




Definition Classes

StrictOptimizedIterableOps -> IterableOps -> IterableOnceOps



Inherited from
StrictOptimizedIterableOps



Source
def find(p: A => Boolean): Option[A]


Finds the first element of the 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. 


Value parameters

p
the predicate used to test elements.



Returns
an option value containing the first element in the collection that satisfies p, or None if none exists.


Inherited from
IterableOnceOps



Source
override def flatMap[B](f: A => IterableOnce[B]): HashSet[B]




Definition Classes

StrictOptimizedIterableOps -> IterableOps -> IterableOnceOps



Inherited from
StrictOptimizedIterableOps



Source
override def flatten[B](implicit toIterableOnce: A => IterableOnce[B]): HashSet[B]




Definition Classes

StrictOptimizedIterableOps -> IterableOps -> IterableOnceOps



Inherited from
StrictOptimizedIterableOps



Source
def fold[A1 >: A](z: A1)(op: (A1, A1) => A1): A1


Folds the elements of this collection using the specified associative binary operator. The default implementation in IterableOnce is equivalent to foldLeft but may be overridden for more efficient traversal orders.
 The order in which operations are performed on elements is unspecified and may be nondeterministic.
 Note: will not terminate for infinite-sized collections. 


Type parameters

A1
a type parameter for the binary operator, a supertype of A.



Value parameters

op
a binary operator that must be associative.
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).



Returns
the result of applying the fold operator op between all the elements and z, or z if this collection is empty.


Inherited from
IterableOnceOps



Source
def foldLeft[B](z: B)(op: (B, A) => B): B


Applies a binary operator to a start value and all elements of this collection, 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. 


Type parameters

B
the result type of the binary operator.



Value parameters

op
the binary operator.
z
the start value.



Returns
the result of inserting op between consecutive elements of this collection, going left to right with the start value z on the left: op(...op(z, x1), x2, ..., xn) where x1, ..., xn are the elements of this collection. Returns z if this collection is empty.


Inherited from
IterableOnceOps



Source
def foldRight[B](z: B)(op: (A, B) => B): B


Applies a binary operator to all elements of this 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.


Type parameters

B
the result type of the binary operator.



Value parameters

op
the binary operator.
z
the start value.



Returns
the result of inserting op between consecutive elements of this collection, going right to left with the start value z on the right: op(x1, op(x2, ... op(xn, z)...)) where x1, ..., xn are the elements of this collection. Returns z if this collection is empty.


Inherited from
IterableOnceOps



Source
def forall(p: A => Boolean): Boolean


Tests whether a predicate holds for all elements of this collection.
 Note: may not terminate for infinite-sized collections. 


Value parameters

p
the predicate used to test elements.



Returns
true if this collection is empty or the given predicate p holds for all elements of this collection, otherwise false.


Inherited from
IterableOnceOps



Source
protected def fromSpecific(coll: IterableOnce[A]): HashSet[A]



Inherited from
IterableFactoryDefaults


Source
def groupBy[K](f: A => K): Map[K, HashSet[A]]


Partitions this iterable collection into a map of iterable collections according to some discriminator function.
 Note: Even when applied to a view or a lazy collection it will always force the elements. 


Type parameters

K
the type of keys returned by the discriminator function.



Value parameters

f
the discriminator function.



Returns

A map from keys to iterable collections such that the following invariant holds:
(xs groupBy f)(k) = xs filter (x => f(x) == k)
 That is, every key k is bound to a iterable collection of those elements x for which f(x) equals k.



Inherited from
IterableOps



Source
def groupMap[K, B](key: A => K)(f: A => B): Map[K, HashSet[B]]


Partitions this iterable collection into a map of iterable collections according to a discriminator function key. Each element in a group is transformed into a value of type B using the value function.
It is equivalent to groupBy(key).mapValues(_.map(f)), but more efficient.
case class User(name: String, age: Int)

def namesByAge(users: Seq[User]): Map[Int, Seq[String]] =
  users.groupMap(_.age)(_.name)
 Note: Even when applied to a view or a lazy collection it will always force the elements. 


Type parameters

B
the type of values returned by the transformation function
K
the type of keys returned by the discriminator function



Value parameters

f
the element transformation function
key
the discriminator function



Inherited from
IterableOps



Source
def groupMapReduce[K, B](key: A => K)(f: A => B)(reduce: (B, B) => B): Map[K, B]


Partitions this iterable collection into a map according to a discriminator function key. All the values that have the same discriminator are then transformed by the f function and then reduced into a single value with the reduce function.
It is equivalent to groupBy(key).mapValues(_.map(f).reduce(reduce)), but more efficient.
def occurrences[A](as: Seq[A]): Map[A, Int] =
  as.groupMapReduce(identity)(_ => 1)(_ + _)
 Note: Even when applied to a view or a lazy collection it will always force the elements. 

Inherited from
IterableOps


Source
def grouped(size: Int): Iterator[HashSet[A]]


Partitions elements in fixed size iterable collections.


Value parameters

size
the number of elements per group



Returns
An iterator producing iterable collections of size size, except the last will be less than size size if the elements don't divide evenly.


See also
scala.collection.Iterator, method grouped


Inherited from
IterableOps



Source
def head: A


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.


Throws

NoSuchElementException
if the iterable collection is empty.



Inherited from
IterableOps



Source
def headOption: Option[A]


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 iterable collection if it is nonempty, None if it is empty.


Inherited from
IterableOps



Source
def init: HashSet[A]


The initial part of the collection without its last element.
 Note: Even when applied to a view or a lazy collection it will always force the elements. 

Inherited from
IterableOps


Source
def inits: Iterator[HashSet[A]]


Iterates over the inits of this iterable collection. The first value will be this iterable collection and the final one will be an empty iterable collection, with the intervening values the results of successive applications of init.
 Note: Even when applied to a view or a lazy collection it will always force the elements. 


Returns
an iterator over all the inits of this iterable collection


Example
List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)


Inherited from
IterableOps



Source
def intersect(that: Set[A]): HashSet[A]


Computes the intersection between this set and another set. 


Value parameters

that
the set to intersect with.



Returns
a new set consisting of all elements that are both in this set and in the given set that.


Inherited from
SetOps



Source
override def isTraversableAgain: Boolean




Definition Classes

IterableOps -> IterableOnceOps



Inherited from
IterableOps



Source
def last: A


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 iterable collection.


Throws

NoSuchElementException
If the iterable collection is empty.



Inherited from
IterableOps



Source
def lastOption: Option[A]


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 iterable collection$ if it is nonempty, None if it is empty.


Inherited from
IterableOps



Source
def lazyZip[B](that: Iterable[B]): LazyZip2[A, B, HashSet[A]]


Analogous to zip except that the elements in each collection are not consumed until a strict operation is invoked on the returned LazyZip2 decorator.
Calls to lazyZip can be chained to support higher arities (up to 4) without incurring the expense of constructing and deconstructing intermediary tuples.
val xs = List(1, 2, 3)
val res = (xs lazyZip xs lazyZip xs lazyZip xs).map((a, b, c, d) => a + b + c + d)
// res == List(4, 8, 12)


Type parameters

B
the type of the second element in each eventual pair



Value parameters

that
the iterable providing the second element of each eventual pair



Returns
a decorator LazyZip2 that allows strict operations to be performed on the lazily evaluated pairs or chained calls to lazyZip. Implicit conversion to Iterable[(A, B)] is also supported.


Inherited from
Iterable



Source
override def map[B](f: A => B): HashSet[B]




Definition Classes

StrictOptimizedIterableOps -> IterableOps -> IterableOnceOps



Inherited from
StrictOptimizedIterableOps



Source
def mapResult[NewTo](f: HashSet[A] => NewTo): Builder[A, NewTo]


A builder resulting from this builder my mapping the result using f.

Inherited from
Builder


Source
def max[B >: A](implicit ord: Ordering[B]): A


Finds the largest element.
 Note: will not terminate for infinite-sized collections. 


Type parameters

B
The type over which the ordering is defined.



Value parameters

ord
An ordering to be used for comparing elements.



Returns
the largest element of this collection with respect to the ordering ord.


Throws

UnsupportedOperationException
if this collection is empty.



Inherited from
IterableOnceOps



Source
def maxBy[B](f: A => B)(implicit cmp: Ordering[B]): A


Finds the first element which yields the largest value measured by function f.
 Note: will not terminate for infinite-sized collections. 


Type parameters

B
The result type of the function f.



Value parameters

cmp
An ordering to be used for comparing elements.
f
The measuring function.



Returns
the first element of this collection with the largest value measured by function f with respect to the ordering cmp.


Throws

UnsupportedOperationException
if this collection is empty.



Inherited from
IterableOnceOps



Source
def maxByOption[B](f: A => B)(implicit cmp: Ordering[B]): Option[A]


Finds the first element which yields the largest value measured by function f.
 Note: will not terminate for infinite-sized collections. 


Type parameters

B
The result type of the function f.



Value parameters

cmp
An ordering to be used for comparing elements.
f
The measuring function.



Returns
an option value containing the first element of this collection with the largest value measured by function f with respect to the ordering cmp.


Inherited from
IterableOnceOps



Source
def maxOption[B >: A](implicit ord: Ordering[B]): Option[A]


Finds the largest element.
 Note: will not terminate for infinite-sized collections. 


Type parameters

B
The type over which the ordering is defined.



Value parameters

ord
An ordering to be used for comparing elements.



Returns
an option value containing the largest element of this collection with respect to the ordering ord.


Inherited from
IterableOnceOps



Source
def min[B >: A](implicit ord: Ordering[B]): A


Finds the smallest element.
 Note: will not terminate for infinite-sized collections. 


Type parameters

B
The type over which the ordering is defined.



Value parameters

ord
An ordering to be used for comparing elements.



Returns
the smallest element of this collection with respect to the ordering ord.


Throws

UnsupportedOperationException
if this collection is empty.



Inherited from
IterableOnceOps



Source
def minBy[B](f: A => B)(implicit cmp: Ordering[B]): A


Finds the first element which yields the smallest value measured by function f.
 Note: will not terminate for infinite-sized collections. 


Type parameters

B
The result type of the function f.



Value parameters

cmp
An ordering to be used for comparing elements.
f
The measuring function.



Returns
the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.


Throws

UnsupportedOperationException
if this collection is empty.



Inherited from
IterableOnceOps



Source
def minByOption[B](f: A => B)(implicit cmp: Ordering[B]): Option[A]


Finds the first element which yields the smallest value measured by function f.
 Note: will not terminate for infinite-sized collections. 


Type parameters

B
The result type of the function f.



Value parameters

cmp
An ordering to be used for comparing elements.
f
The measuring function.



Returns
an option value containing the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.


Inherited from
IterableOnceOps



Source
def minOption[B >: A](implicit ord: Ordering[B]): Option[A]


Finds the smallest element.
 Note: will not terminate for infinite-sized collections. 


Type parameters

B
The type over which the ordering is defined.



Value parameters

ord
An ordering to be used for comparing elements.



Returns
an option value containing the smallest element of this collection with respect to the ordering ord.


Inherited from
IterableOnceOps



Source@inline 
final def mkString: String


Displays all elements of this collection in a string.
Delegates to addString, which can be overridden. 


Returns
a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection follow each other without any separator string.


Inherited from
IterableOnceOps



Source@inline 
final def mkString(sep: String): String


Displays all elements of this collection in a string using a separator string.
Delegates to addString, which can be overridden. 


Value parameters

sep
the separator string.



Returns
a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.


Example
List(1, 2, 3).mkString("|") = "1|2|3"


Inherited from
IterableOnceOps



Source
final def mkString(start: String, sep: String, end: String): String


Displays all elements of this collection in a string using start, end, and separator strings.
Delegates to addString, which can be overridden. 


Value parameters

end
the ending string.
sep
the separator string.
start
the starting string.



Returns
a string representation of this collection. The resulting string begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.


Example
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"


Inherited from
IterableOnceOps



Source
protected def newSpecificBuilder: Builder[A, HashSet[A]]



Inherited from
IterableFactoryDefaults


Source@deprecatedOverriding("nonEmpty is defined as !isEmpty; override isEmpty instead", "2.13.0") 
def nonEmpty: Boolean


Tests whether the collection is not empty. 


Returns
true if the collection contains at least one element, false otherwise.


Inherited from
IterableOnceOps



Source
override def partition(p: A => Boolean): (HashSet[A], HashSet[A])




Definition Classes

StrictOptimizedIterableOps -> IterableOps



Inherited from
StrictOptimizedIterableOps



Source
override def partitionMap[A1, A2](f: A => Either[A1, A2]): (HashSet[A1], HashSet[A2])




Definition Classes

StrictOptimizedIterableOps -> IterableOps



Inherited from
StrictOptimizedIterableOps



Source
def product[B >: A](implicit num: Numeric[B]): B


Multiplies up the elements of this collection.
 Note: will not terminate for infinite-sized collections. 


Type parameters

B
the result type of the * operator.



Value parameters

num
an implicit parameter defining a set of numeric operations which includes the * operator to be used in forming the product.



Returns
the product of all elements of this collection with respect to the * operator in num.


Inherited from
IterableOnceOps



Source
def reduce[B >: A](op: (B, B) => B): B


Reduces the elements of this collection using the specified associative binary operator.
 The order in which operations are performed on elements is unspecified and may be nondeterministic. 


Type parameters

B
A type parameter for the binary operator, a supertype of A.



Value parameters

op
A binary operator that must be associative.



Returns
The result of applying reduce operator op between all the elements if the collection is nonempty.


Throws

UnsupportedOperationException
if this collection is empty.



Inherited from
IterableOnceOps



Source
def reduceLeft[B >: A](op: (B, A) => B): B


Applies a binary operator to all elements of this collection, 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. 


Type parameters

B
the result type of the binary operator.



Value parameters

op
the binary operator.



Returns
the result of inserting op between consecutive elements of this collection, going left to right: op( op( ... op(x1, x2) ..., xn-1), xn) where x1, ..., xn are the elements of this collection.


Throws

UnsupportedOperationException
if this collection is empty.



Inherited from
IterableOnceOps



Source
def reduceLeftOption[B >: A](op: (B, A) => B): Option[B]


Optionally applies a binary operator to all elements of this collection, 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. 


Type parameters

B
the result type of the binary operator.



Value parameters

op
the binary operator.



Returns
an option value containing the result of reduceLeft(op) if this collection is nonempty, None otherwise.


Inherited from
IterableOnceOps



Source
def reduceOption[B >: A](op: (B, B) => B): Option[B]


Reduces the elements of this collection, if any, using the specified associative binary operator.
 The order in which operations are performed on elements is unspecified and may be nondeterministic. 


Type parameters

B
A type parameter for the binary operator, a supertype of A.



Value parameters

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, and None otherwise.


Inherited from
IterableOnceOps



Source
def reduceRight[B >: A](op: (A, B) => B): B


Applies a binary operator to all elements of this 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. 


Type parameters

B
the result type of the binary operator.



Value parameters

op
the binary operator.



Returns
the result of inserting op between consecutive elements of this collection, going right to left: op(x1, op(x2, ..., op(xn-1, xn)...)) where x1, ..., xn are the elements of this collection.


Throws

UnsupportedOperationException
if this collection is empty.



Inherited from
IterableOnceOps



Source
def reduceRightOption[B >: A](op: (A, B) => B): Option[B]


Optionally applies a binary operator to all elements of this 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. 


Type parameters

B
the result type of the binary operator.



Value parameters

op
the binary operator.



Returns
an option value containing the result of reduceRight(op) if this collection is nonempty, None otherwise.


Inherited from
IterableOnceOps



Source
def result(): HashSet[A]



Inherited from
SetOps


Source
protected def reversed: Iterable[A]



Inherited from
IterableOnceOps


Source
def scan[B >: A](z: B)(op: (B, B) => B): HashSet[B]


Computes a prefix scan of the elements of the collection.
Note: The neutral element z may be applied more than once. 


Type parameters

B
element type of the resulting collection



Value parameters

op
the associative operator for the scan
z
neutral element for the operator op



Returns
a new iterable collection containing the prefix scan of the elements in this iterable collection


Inherited from
IterableOps



Source
override def scanLeft[B](z: B)(op: (B, A) => B): HashSet[B]




Definition Classes

StrictOptimizedIterableOps -> IterableOps -> IterableOnceOps



Inherited from
StrictOptimizedIterableOps



Source
def scanRight[B](z: B)(op: (A, B) => B): HashSet[B]


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.
 Note: Even when applied to a view or a lazy collection it will always force the elements.
Example:
List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)


Type parameters

B
the type of the elements in the resulting collection



Value parameters

op
the binary operator applied to the intermediate result and the element
z
the initial value



Returns
collection with intermediate results


Inherited from
IterableOps



Source
def sizeCompare(that: Iterable[_]): Int


Compares the size of this iterable collection to the size of another Iterable. 


Value parameters

that
the Iterable whose size is compared with this iterable collection's size.



Returns

A value x where
x <  0       if this.size <  that.size
x == 0       if this.size == that.size
x >  0       if this.size >  that.size
The method as implemented here does not call size directly; its running time is O(this.size min that.size) instead of O(this.size + that.size). The method should be overridden if computing size is cheap and knownSize returns -1.



Inherited from
IterableOps



Source
def sizeCompare(otherSize: Int): Int


Compares the size of this iterable collection to a test value. 


Value parameters

otherSize
the test value that gets compared with the size.



Returns

A value x where
x <  0       if this.size <  otherSize
x == 0       if this.size == otherSize
x >  0       if this.size >  otherSize
The method as implemented here does not call size directly; its running time is O(size min otherSize) instead of O(size). The method should be overridden if computing size is cheap and knownSize returns -1.



See also
sizeIs


Inherited from
IterableOps



Source
final def sizeHint(coll: IterableOnce[_], 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 has a known size 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. 


Value parameters

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.



Inherited from
Builder



Source
final def sizeHintBounded(size: Int, boundingColl: Iterable[_]): 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. 


Value parameters

boundingColl
the bounding collection. If it is an IndexedSeqLike, then sizes larger than collection's size are reduced.
size
the hint how many elements will be added.



Inherited from
Builder



Source@inline 
final def sizeIs: SizeCompareOps


Returns a value class containing operations for comparing the size of this iterable collection to a test value.
These operations are implemented in terms of sizeCompare(Int), and allow the following more readable usages:
this.sizeIs < size     // this.sizeCompare(size) < 0
this.sizeIs <= size    // this.sizeCompare(size) <= 0
this.sizeIs == size    // this.sizeCompare(size) == 0
this.sizeIs != size    // this.sizeCompare(size) != 0
this.sizeIs >= size    // this.sizeCompare(size) >= 0
this.sizeIs > size     // this.sizeCompare(size) > 0

Inherited from
IterableOps


Source
def slice(from: Int, until: Int): HashSet[A]



Inherited from
IterableOps


Source
def sliding(size: Int, step: Int): Iterator[HashSet[A]]


Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
The returned iterator will be empty when called on an empty collection. The last element the iterator produces may be smaller than the window size when the original collection isn't exhausted by the window before it and its last element isn't skipped by the step before it. 


Value parameters

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 element (which may be the only element) will be smaller if there are fewer than size elements remaining to be grouped.


See also
scala.collection.Iterator, method sliding


Example

List(1, 2, 3, 4, 5).sliding(2, 2) = Iterator(List(1, 2), List(3, 4), List(5))
List(1, 2, 3, 4, 5, 6).sliding(2, 3) = Iterator(List(1, 2), List(4, 5))



Inherited from
IterableOps



Source
def sliding(size: Int): Iterator[HashSet[A]]


Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
An empty collection returns an empty iterator, and a non-empty collection containing fewer elements than the window size returns an iterator that will produce the original collection as its only element.


Value parameters

size
the number of elements per group



Returns
An iterator producing iterable collections of size size, except for a non-empty collection with less than size elements, which returns an iterator that produces the source collection itself as its only element.


See also
scala.collection.Iterator, method sliding


Example

List().sliding(2) = empty iterator
List(1).sliding(2) = Iterator(List(1))
List(1, 2).sliding(2) = Iterator(List(1, 2))
List(1, 2, 3).sliding(2) = Iterator(List(1, 2), List(2, 3))



Inherited from
IterableOps



Source
override def span(p: A => Boolean): (HashSet[A], HashSet[A])




Definition Classes

StrictOptimizedIterableOps -> IterableOps -> IterableOnceOps



Inherited from
StrictOptimizedIterableOps



Source
override def splitAt(n: Int): (HashSet[A], HashSet[A])




Definition Classes

IterableOps -> IterableOnceOps



Inherited from
IterableOps



Source
def subsetOf(that: Set[A]): Boolean


Tests whether this set is a subset of another set. 


Value parameters

that
the set to test.



Returns
true if this set is a subset of that, i.e. if every element of this set is also an element of that.


Inherited from
SetOps



Source
def subsets(): Iterator[HashSet[A]]


An iterator over all subsets of this set. 


Returns
the iterator.


Inherited from
SetOps



Source
def subsets(len: Int): Iterator[HashSet[A]]


An iterator over all subsets of this set of the given size. If the requested size is impossible, an empty iterator is returned. 


Value parameters

len
the size of the subsets.



Returns
the iterator.


Inherited from
SetOps



Source
def sum[B >: A](implicit num: Numeric[B]): B


Sums up the elements of this collection.
 Note: will not terminate for infinite-sized collections. 


Type parameters

B
the result type of the + operator.



Value parameters

num
an implicit parameter defining a set of numeric operations which includes the + operator to be used in forming the sum.



Returns
the sum of all elements of this collection with respect to the + operator in num.


Inherited from
IterableOnceOps



Source
def tail: HashSet[A]


The rest of the collection without its first element.

Inherited from
IterableOps


Source
def tails: Iterator[HashSet[A]]


Iterates over the tails of this iterable collection. The first value will be this iterable collection and the final one will be an empty iterable collection, with the intervening values the results of successive applications of tail. 


Returns
an iterator over all the tails of this iterable collection


Example
List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)


Inherited from
IterableOps



Source
def take(n: Int): HashSet[A]



Inherited from
IterableOps


Source
override def takeRight(n: Int): HashSet[A]


A collection containing the last n elements of this collection.
 Note: Even when applied to a view or a lazy collection it will always force the elements. 


Definition Classes

StrictOptimizedIterableOps -> IterableOps



Inherited from
StrictOptimizedIterableOps



Source
def takeWhile(p: A => Boolean): HashSet[A]


Takes longest prefix of elements that satisfy a predicate.
 Note: might return different results for different runs, unless the underlying collection type is ordered.


Value parameters

p
The predicate used to test elements.



Returns
the longest prefix of this iterable collection whose elements all satisfy the predicate p.


Inherited from
IterableOps



Source
override def tapEach[U](f: A => U): HashSet[A]




Definition Classes

StrictOptimizedIterableOps -> IterableOps -> IterableOnceOps



Inherited from
StrictOptimizedIterableOps



Source
def to[C1](factory: Factory[A, C1]): C1


Given a collection factory factory, convert this collection to the appropriate representation for the current element type A. Example uses:
 xs.to(List) xs.to(ArrayBuffer) xs.to(BitSet) // for xs: Iterable[Int] 

Inherited from
IterableOnceOps


Source
def toArray[B >: A : ClassTag]: Array[B]


Convert collection to array.
Implementation note: DO NOT call Array.from from this method. 

Inherited from
IterableOnceOps


Source@inline 
final def toBuffer[B >: A]: Buffer[B]



Inherited from
IterableOnceOps


Source
def toIndexedSeq: IndexedSeq[A]



Inherited from
IterableOnceOps


Source
def toList: List[A]



Inherited from
IterableOnceOps


Source
def toMap[K, V](implicit ev: A <:< (K, V)): Map[K, V]



Inherited from
IterableOnceOps


Source
def toSeq: Seq[A]




Returns
This collection as a Seq[A]. This is equivalent to to(Seq) but might be faster.


Inherited from
IterableOnceOps



Source
def toSet[B >: A]: Set[B]



Inherited from
IterableOnceOps


Source
override def toString(): String




Definition Classes

Set -> Function1 -> Iterable -> Any



Inherited from
Set



Source
def toVector: Vector[A]



Inherited from
IterableOnceOps


Source
def transpose[B](implicit asIterable: A => Iterable[B]): HashSet[HashSet[B]]


Transposes this iterable collection of iterable collections into a iterable collection of iterable collections.
 The resulting collection's type will be guided by the static type of iterable collection. For example:
val xs = List(
           Set(1, 2, 3),
           Set(4, 5, 6)).transpose
// xs == List(
//         List(1, 4),
//         List(2, 5),
//         List(3, 6))

val ys = Vector(
           List(1, 2, 3),
           List(4, 5, 6)).transpose
// ys == Vector(
//         Vector(1, 4),
//         Vector(2, 5),
//         Vector(3, 6))
 Note: Even when applied to a view or a lazy collection it will always force the elements. 


Type parameters

B
the type of the elements of each iterable collection.



Value parameters

asIterable
an implicit conversion which asserts that the element type of this iterable collection is an Iterable.



Returns
a two-dimensional iterable collection of iterable collections which has as nth row the nth column of this iterable collection.


Throws

IllegalArgumentException
if all collections in this iterable collection are not of the same size.



Inherited from
IterableOps



Source@inline 
final def union(that: Set[A]): HashSet[A]


Computes the union between of set and another set. 


Value parameters

that
the set to form the union with.



Returns
a new set consisting of all elements that are in this set or in the given set that.


Inherited from
SetOps



Source
override def unzip[A1, A2](implicit asPair: A => (A1, A2)): (HashSet[A1], HashSet[A2])




Definition Classes

StrictOptimizedIterableOps -> IterableOps



Inherited from
StrictOptimizedIterableOps



Source
override def unzip3[A1, A2, A3](implicit asTriple: A => (A1, A2, A3)): (HashSet[A1], HashSet[A2], HashSet[A3])




Definition Classes

StrictOptimizedIterableOps -> IterableOps



Inherited from
StrictOptimizedIterableOps



Source
def update(elem: A, included: Boolean): Unit


Updates the presence of a single element in this set.
This method allows one to add or remove an element elem from this set depending on the value of parameter included. Typically, one would use the following syntax:
set(elem) = true  // adds element
set(elem) = false // removes element


Value parameters

elem
the element to be added or removed
included
a flag indicating whether element should be included or excluded.



Inherited from
SetOps



Source
def view: View[A]


A view over the elements of this collection.

Inherited from
IterableOps


Source
def withFilter(p: A => Boolean): WithFilter[A, HashSet]


Creates a non-strict filter of this iterable 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. 


Value parameters

p
the predicate used to test elements.



Returns
an object of class WithFilter, which supports map, flatMap, foreach, and withFilter operations. All these operations apply to those elements of this iterable collection which satisfy the predicate p.


Inherited from
IterableOps



Source
override def zip[B](that: IterableOnce[B]): HashSet[(A, B)]




Definition Classes

StrictOptimizedIterableOps -> IterableOps



Inherited from
StrictOptimizedIterableOps



Source
def zipAll[A1 >: A, B](that: Iterable[B], thisElem: A1, thatElem: B): HashSet[(A1, B)]


Returns a iterable collection formed from this iterable collection 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. 


Value parameters

that
the iterable providing the second half of each result pair
thatElem
the element to be used to fill up the result if that is shorter than this iterable collection.
thisElem
the element to be used to fill up the result if this iterable collection is shorter than that.



Returns
a new collection of type That containing pairs consisting of corresponding elements of this iterable collection and that. The length of the returned collection is the maximum of the lengths of this iterable collection and that. If this iterable collection is shorter than that, thisElem values are used to pad the result. If that is shorter than this iterable collection, thatElem values are used to pad the result.


Inherited from
IterableOps



Source
override def zipWithIndex: HashSet[(A, Int)]




Definition Classes

StrictOptimizedIterableOps -> IterableOps -> IterableOnceOps



Inherited from
StrictOptimizedIterableOps



Source@inline 
final def |(that: Set[A]): HashSet[A]


Alias for union

Inherited from
SetOps


    
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