Trait scala.collection.Stepper
Companion object Stepper
trait Stepper[+A] extends AnyRef
Abstract Value Members
abstract def characteristics: Int
Returns a set of characteristics of this Stepper and its elements. See method characteristics
in Spliterator.
abstract def estimateSize: Long
Returns an estimate of the number of elements of this Stepper, or Long.MaxValue. See method estimateSize
in Spliterator.
abstract def hasStep: Boolean
abstract def javaIterator[B >: A]: java.util.Iterator[_]
Returns a Java JIterator corresponding to this Stepper.
Note that the return type is Iterator[_]
instead of Iterator[A]
to allow returning a java.util.PrimitiveIterator.OfInt (which is a Iterator[Integer]
) in the subclass IntStepper (which is a Stepper[Int]
).
abstract def nextStep(): A
abstract def spliterator[B >: A]: Spliterator[_]
Returns a Spliterator corresponding to this Stepper.
Note that the return type is Spliterator[_]
instead of Spliterator[A]
to allow returning a Spliterator.OfInt (which is a Spliterator[Integer]
) in the subclass IntStepper (which is a Stepper[Int]
).
abstract def trySplit(): Stepper[A]
Split this stepper, if applicable. The elements of the current Stepper are split up between the resulting Stepper and the current stepper.
May return null
, in which case the current Stepper yields the same elements as before.
See method trySplit
in Spliterator.
Concrete Value Members
final def !=(arg0: Any): Boolean
Test two objects for inequality.
- returns
true
if !(this == that), false otherwise.
- Definition Classes
- AnyRef → Any
final def ##(): Int
Equivalent to x.hashCode
except for boxed numeric types and null
. 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. For null
returns a hashcode where null.hashCode
throws a NullPointerException
.
- returns
a hash value consistent with ==
- Definition Classes
- AnyRef → Any
def +(other: String): String
- Implicit
- This member is added by an implicit conversion from Stepper[A] toany2stringadd[Stepper[A]] performed by method any2stringadd in scala.Predef.
- Definition Classes
- any2stringadd
def ->[B](y: B): (Stepper[A], B)
- Implicit
- This member is added by an implicit conversion from Stepper[A] toArrowAssoc[Stepper[A]] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
- Annotations
- @inline()
final def ==(arg0: Any): Boolean
The expression x == that
is equivalent to if (x eq null) that eq null else x.equals(that)
.
- returns
true
if the receiver object is equivalent to the argument;false
otherwise.
- Definition Classes
- AnyRef → Any
final def asInstanceOf[T0]: 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 a ClassCastException
at runtime, while the expression List(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
ClassCastException
if the receiver object is not an instance of the erasure of typeT0
.
def clone(): AnyRef
Create a copy of the receiver object.
The default implementation of the clone
method is platform dependent.
- returns
a copy of the receiver object.
def ensuring(cond: (Stepper[A]) => Boolean, msg: => Any): Stepper[A]
- Implicit
- This member is added by an implicit conversion from Stepper[A] toEnsuring[Stepper[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
def ensuring(cond: (Stepper[A]) => Boolean): Stepper[A]
- Implicit
- This member is added by an implicit conversion from Stepper[A] toEnsuring[Stepper[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
def ensuring(cond: Boolean, msg: => Any): Stepper[A]
- Implicit
- This member is added by an implicit conversion from Stepper[A] toEnsuring[Stepper[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
def ensuring(cond: Boolean): Stepper[A]
- Implicit
- This member is added by an implicit conversion from Stepper[A] toEnsuring[Stepper[A]] 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
).
The eq
method implements an equivalence relation on non-null instances of AnyRef
, and has three additional properties:
-
It is consistent: for any non-null instances
x
and y
of type AnyRef
, multiple invocations of x.eq(y)
consistently returns true
or consistently returns false
.For any non-null instance x
of type AnyRef
, x.eq(null)
and null.eq(x)
returns false
.
null.eq(null)
returns true
. When overriding the equals
or hashCode
methods, 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
true
if the argument is a reference to the receiver object;false
otherwise.
- Definition Classes
- AnyRef
def equals(arg0: AnyRef): Boolean
The equality method for reference types. Default implementation delegates to eq
.
See also equals
in scala.Any.
- returns
true
if the receiver object is equivalent to the argument;false
otherwise.
- Definition Classes
- AnyRef → Any
def finalize(): Unit
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 finalize
method is invoked, as well as the interaction between finalize
and non-local returns and exceptions, are all platform dependent.
def formatted(fmtstr: String): String
Returns string formatted according to given format
string. Format strings are as for String.format
(@see java.lang.String.format).
- Implicit
- This member is added by an implicit conversion from Stepper[A] toStringFormat[Stepper[A]] performed by method StringFormat in scala.Predef.
- Definition Classes
- StringFormat
- Annotations
- @inline()
final def getClass(): Class[_ <: AnyRef]
Returns the runtime class representation of the object.
- returns
a class object corresponding to the runtime type of the receiver.
def hashCode(): Int
The hashCode method for reference types. See hashCode in scala.Any.
- returns
the hash code value for this object.
final def isInstanceOf[T0]: Boolean
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 return false
, while the expression List(1).isInstanceOf[List[String]]
will return true
. 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
true
if the receiver object is an instance of erasure of typeT0
;false
otherwise.
- Definition Classes
- Any
def iterator: Iterator[A]
Returns an Iterator corresponding to this Stepper. Note that Iterators corresponding to primitive Steppers box the elements.
final def ne(arg0: AnyRef): Boolean
Equivalent to !(this eq that)
.
- returns
true
if the argument is not a reference to the receiver object;false
otherwise.
- Definition Classes
- AnyRef
final def notify(): Unit
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.
- 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 toString(): String
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
final def wait(): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws(classOf[java.lang.InterruptedException])
final def wait(arg0: Long, arg1: Int): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws(classOf[java.lang.InterruptedException])
final def wait(arg0: Long): Unit
© 2002-2019 EPFL, with contributions from Lightbend.
Licensed under the Apache License, Version 2.0.
https://www.scala-lang.org/api/2.13.0/scala/collection/Stepper.html
Steppers exist to enable creating Java streams over Scala collections, see scala.jdk.StreamConverters. Besides that use case, they allow iterating over collections holding unboxed primitives (e.g.,
Array[Int]
) without boxing the elements.Steppers have an iterator-like interface with methods
hasStep
andnextStep()
. The difference to iterators - and the reasonStepper
is not a subtype ofIterator
- is that there are hand-specialized variants ofStepper
forInt
,Long
andDouble
(IntStepper, etc.). These enable iterating over collections holding unboxed primitives (e.g., Arrays, scala.jdk.Accumulators) without boxing the elements.The selection of primitive types (
Int
,Long
andDouble
) matches the hand-specialized variants of Java Streams (java.util.stream.Stream, java.util.stream.IntStream, etc.) and the corresponding Java Spliterators (Spliterator, Spliterator.OfInt, etc.).Steppers can be converted to Scala Iterators, Java Iterators and Java Spliterators. Primitive Steppers are converted to the corresponding primitive Java Iterators and Spliterators.
the element type of the Stepper