trait GenericTraversableTemplate[+A, +CC[X] <: GenTraversable[X]] extends HasNewBuilder[A, CC[A]]
A template class for companion objects of collection classes
that represent an unconstrained higher-kinded type.
regular
- A
The type of the collection elements.
- CC
The type constructor representing the collection class.
- Source
- GenericTraversableTemplate.scala
- Since
2.8
- Alphabetic
- By Inheritance
- GenericTraversableTemplate
- HasNewBuilder
- AnyRef
- Any
- by CollectionsHaveToParArray
- by any2stringadd
- by StringFormat
- by Ensuring
- by ArrowAssoc
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Abstract Value Members
-
abstract
def
companion: GenericCompanion[CC]
The factory companion object that builds instances of class Traversable.
The factory companion object that builds instances of class Traversable. (or its
Iterablesuperclass where class Traversable is not aSeq.) -
abstract
def
head: A
Selects the first element of this collection.
Selects the first element of this collection.
- returns
the first element of this collection.
- Exceptions thrown
NoSuchElementExceptionif the collection is empty.
-
abstract
def
isEmpty: Boolean
Tests whether this collection is empty.
Tests whether this collection is empty.
- returns
trueif the collection contain no elements,falseotherwise.
Concrete Value Members
-
final
def
!=(arg0: Any): Boolean
Test two objects for inequality.
Test two objects for inequality.
- returns
trueif !(this == that), false otherwise.
- Definition Classes
- AnyRef → Any
-
final
def
##(): Int
Equivalent to
x.hashCodeexcept for boxed numeric types andnull.Equivalent to
x.hashCodeexcept for boxed numeric types andnull. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. Fornullreturns a hashcode wherenull.hashCodethrows aNullPointerException.- returns
a hash value consistent with ==
- Definition Classes
- AnyRef → Any
-
def
+(other: String): String
- Implicit
- This member is added by an implicit conversion from GenericTraversableTemplate[A, CC] to any2stringadd[GenericTraversableTemplate[A, CC]] performed by method any2stringadd in scala.Predef.
- Definition Classes
- any2stringadd
-
def
->[B](y: B): (GenericTraversableTemplate[A, CC], B)
- Implicit
- This member is added by an implicit conversion from GenericTraversableTemplate[A, CC] to ArrowAssoc[GenericTraversableTemplate[A, CC]] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
- Annotations
- @inline()
-
final
def
==(arg0: Any): Boolean
The expression
x == thatis equivalent toif (x eq null) that eq null else x.equals(that).The expression
x == thatis equivalent toif (x eq null) that eq null else x.equals(that).- returns
trueif the receiver object is equivalent to the argument;falseotherwise.
- Definition Classes
- AnyRef → Any
-
final
def
asInstanceOf[T0]: T0
Cast the receiver object to be of type
T0.Cast the receiver object to be of type
T0.Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression
1.asInstanceOf[String]will throw aClassCastExceptionat runtime, while the expressionList(1).asInstanceOf[List[String]]will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.- returns
the receiver object.
- Definition Classes
- Any
- Exceptions thrown
ClassCastExceptionif the receiver object is not an instance of the erasure of typeT0.
-
def
clone(): AnyRef
Create a copy of the receiver object.
-
def
ensuring(cond: (GenericTraversableTemplate[A, CC]) ⇒ Boolean, msg: ⇒ Any): GenericTraversableTemplate[A, CC]
- Implicit
- This member is added by an implicit conversion from GenericTraversableTemplate[A, CC] to Ensuring[GenericTraversableTemplate[A, CC]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: (GenericTraversableTemplate[A, CC]) ⇒ Boolean): GenericTraversableTemplate[A, CC]
- Implicit
- This member is added by an implicit conversion from GenericTraversableTemplate[A, CC] to Ensuring[GenericTraversableTemplate[A, CC]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: Boolean, msg: ⇒ Any): GenericTraversableTemplate[A, CC]
- Implicit
- This member is added by an implicit conversion from GenericTraversableTemplate[A, CC] to Ensuring[GenericTraversableTemplate[A, CC]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: Boolean): GenericTraversableTemplate[A, CC]
- Implicit
- This member is added by an implicit conversion from GenericTraversableTemplate[A, CC] to Ensuring[GenericTraversableTemplate[A, CC]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
final
def
eq(arg0: AnyRef): Boolean
Tests whether the argument (
that) is a reference to the receiver object (this).Tests whether the argument (
that) is a reference to the receiver object (this).The
eqmethod implements an equivalence relation on non-null instances ofAnyRef, and has three additional properties:- It is consistent: for any non-null instances
xandyof typeAnyRef, multiple invocations ofx.eq(y)consistently returnstrueor consistently returnsfalse. - For any non-null instance
xof typeAnyRef,x.eq(null)andnull.eq(x)returnsfalse. null.eq(null)returnstrue.
When overriding the
equalsorhashCodemethods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).- returns
trueif the argument is a reference to the receiver object;falseotherwise.
- Definition Classes
- AnyRef
- It is consistent: for any non-null instances
-
def
equals(arg0: Any): Boolean
The equality method for reference types.
-
def
finalize(): Unit
Called by the garbage collector on the receiver object when there are no more references to the object.
Called by the garbage collector on the receiver object when there are no more references to the object.
The details of when and if the
finalizemethod is invoked, as well as the interaction betweenfinalizeand non-local returns and exceptions, are all platform dependent. -
def
flatten[B]: Traversable[B]
[use case] Converts this collection of traversable collections into a collection formed by the elements of these traversable collections.
[use case]Converts this collection of traversable collections into a collection formed by the elements of these traversable collections.
The resulting collection's type will be guided by the static type of collection. For example:
val xs = List( Set(1, 2, 3), Set(1, 2, 3) ).flatten // xs == List(1, 2, 3, 1, 2, 3) val ys = Set( List(1, 2, 3), List(3, 2, 1) ).flatten // ys == Set(1, 2, 3)
- B
the type of the elements of each traversable collection.
- returns
a new collection resulting from concatenating all element collections.
Full Signaturedef flatten[B](implicit asTraversable: (A) ⇒ GenTraversableOnce[B]): CC[B]
-
abstract
def
foreach(f: (A) ⇒ Unit): Unit
[use case]
[use case]- f
the function that is applied for its side-effect to every element. The result of function
fis discarded.
Full Signatureabstract def foreach[U](f: (A) ⇒ U): Unit
-
def
formatted(fmtstr: String): String
Returns string formatted according to given
formatstring.Returns string formatted according to given
formatstring. Format strings are as forString.format(@see java.lang.String.format).- Implicit
- This member is added by an implicit conversion from GenericTraversableTemplate[A, CC] to StringFormat[GenericTraversableTemplate[A, CC]] performed by method StringFormat in scala.Predef.
- Definition Classes
- StringFormat
- Annotations
- @inline()
-
def
genericBuilder[B]: Builder[B, CC[B]]
The generic builder that builds instances of Traversable at arbitrary element types.
-
final
def
getClass(): Class[_]
Returns the runtime class representation of the object.
-
def
hashCode(): Int
The hashCode method for reference types.
-
final
def
isInstanceOf[T0]: Boolean
Test whether the dynamic type of the receiver object is
T0.Test whether the dynamic type of the receiver object is
T0.Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression
1.isInstanceOf[String]will returnfalse, while the expressionList(1).isInstanceOf[List[String]]will returntrue. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.- returns
trueif the receiver object is an instance of erasure of typeT0;falseotherwise.
- Definition Classes
- Any
-
final
def
ne(arg0: AnyRef): Boolean
Equivalent to
!(this eq that).Equivalent to
!(this eq that).- returns
trueif the argument is not a reference to the receiver object;falseotherwise.
- Definition Classes
- AnyRef
-
def
newBuilder: Builder[A, CC[A]]
The builder that builds instances of type Traversable[A]
The builder that builds instances of type Traversable[A]
- Attributes
- protected[this]
- Definition Classes
- GenericTraversableTemplate → HasNewBuilder
-
final
def
notify(): Unit
Wakes up a single thread that is waiting on the receiver object's monitor.
Wakes up a single thread that is waiting on the receiver object's monitor.
- Definition Classes
- AnyRef
- Annotations
- @native()
- Note
not specified by SLS as a member of AnyRef
-
final
def
notifyAll(): Unit
Wakes up all threads that are waiting on the receiver object's monitor.
Wakes up all threads that are waiting on the receiver object's monitor.
- Definition Classes
- AnyRef
- Annotations
- @native()
- Note
not specified by SLS as a member of AnyRef
-
final
def
synchronized[T0](arg0: ⇒ T0): T0
- Definition Classes
- AnyRef
-
def
toParArray: ParArray[T]
- Implicit
- This member is added by an implicit conversion from GenericTraversableTemplate[A, CC] to CollectionsHaveToParArray[GenericTraversableTemplate[A, CC], T] performed by method CollectionsHaveToParArray in scala.collection.parallel. This conversion will take place only if an implicit value of type (GenericTraversableTemplate[A, CC]) ⇒ GenTraversableOnce[T] is in scope.
- Definition Classes
- CollectionsHaveToParArray
-
def
toString(): String
Creates a String representation of this object.
Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.
- returns
a String representation of the object.
- Definition Classes
- AnyRef → Any
-
def
transpose[B](implicit asTraversable: (A) ⇒ GenTraversableOnce[B]): CC[CC[B]]
Transposes this collection of traversable collections into a collection of collections.
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:
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))
- 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.- returns
a two-dimensional collection of collections which has as nth row the nth column of this collection.
- Annotations
- @migration
- Migration
(Changed in version 2.9.0)
transposethrows anIllegalArgumentExceptionif collections are not uniformly sized.- Exceptions thrown
IllegalArgumentExceptionif all collections in this collection are not of the same size.
-
def
unzip[A1, A2](implicit asPair: (A) ⇒ (A1, A2)): (CC[A1], CC[A2])
Converts this collection of pairs into two collections of the first and second half of each pair.
Converts this collection of pairs into two collections of the first and second half of each pair.
val xs = Traversable( (1, "one"), (2, "two"), (3, "three")).unzip // xs == (Traversable(1, 2, 3), // Traversable(one, two, three))
- 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.
-
def
unzip3[A1, A2, A3](implicit asTriple: (A) ⇒ (A1, A2, A3)): (CC[A1], CC[A2], CC[A3])
Converts this collection of triples into three collections of the first, second, and third element of each triple.
Converts this collection of triples into three collections of the first, second, and third element of each triple.
val xs = Traversable( (1, "one", '1'), (2, "two", '2'), (3, "three", '3')).unzip3 // xs == (Traversable(1, 2, 3), // Traversable(one, two, three), // Traversable(1, 2, 3))
- 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.
-
final
def
wait(): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
final
def
wait(arg0: Long, arg1: Int): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
- final def wait(arg0: Long): Unit
-
def
→[B](y: B): (GenericTraversableTemplate[A, CC], B)
- Implicit
- This member is added by an implicit conversion from GenericTraversableTemplate[A, CC] to ArrowAssoc[GenericTraversableTemplate[A, CC]] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
This is the documentation for the Scala standard library.
Package structure
The scala package contains core types like
Int,Float,ArrayorOptionwhich are accessible in all Scala compilation units without explicit qualification or imports.Notable packages include:
scala.collectionand its sub-packages contain Scala's collections frameworkscala.collection.immutable- Immutable, sequential data-structures such asVector,List,Range,HashMaporHashSetscala.collection.mutable- Mutable, sequential data-structures such asArrayBuffer,StringBuilder,HashMaporHashSetscala.collection.concurrent- Mutable, concurrent data-structures such asTrieMapscala.collection.parallel.immutable- Immutable, parallel data-structures such asParVector,ParRange,ParHashMaporParHashSetscala.collection.parallel.mutable- Mutable, parallel data-structures such asParArray,ParHashMap,ParTrieMaporParHashSetscala.concurrent- Primitives for concurrent programming such asFuturesandPromisesscala.io- Input and output operationsscala.math- Basic math functions and additional numeric types likeBigIntandBigDecimalscala.sys- Interaction with other processes and the operating systemscala.util.matching- Regular expressionsOther packages exist. See the complete list on the right.
Additional parts of the standard library are shipped as separate libraries. These include:
scala.reflect- Scala's reflection API (scala-reflect.jar)scala.xml- XML parsing, manipulation, and serialization (scala-xml.jar)scala.swing- A convenient wrapper around Java's GUI framework called Swing (scala-swing.jar)scala.util.parsing- Parser combinators (scala-parser-combinators.jar)Automatic imports
Identifiers in the scala package and the
scala.Predefobject are always in scope by default.Some of these identifiers are type aliases provided as shortcuts to commonly used classes. For example,
Listis an alias forscala.collection.immutable.List.Other aliases refer to classes provided by the underlying platform. For example, on the JVM,
Stringis an alias forjava.lang.String.