object Sorting
The Sorting object provides convenience wrappers for java.util.Arrays.sort.
Methods that defer to java.util.Arrays.sort say that they do or under what
conditions that they do.
Sorting also implements a general-purpose quicksort and stable (merge) sort
for those cases where java.util.Arrays.sort could only be used at the cost
of a large memory penalty. If performance rather than memory usage is the
primary concern, one may wish to find alternate strategies to use
java.util.Arrays.sort directly e.g. by boxing primitives to use
a custom ordering on them.
Sorting provides methods where you can provide a comparison function, or
can request a sort of items that are scala.math.Ordered or that
otherwise have an implicit or explicit scala.math.Ordering.
Note also that high-performance non-default sorts for numeric types are not provided. If this is required, it is advisable to investigate other libraries that cover this use case.
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- Sorting.scala
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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
-
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.
-
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. -
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
-
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
-
def
quickSort[K](a: Array[K])(implicit arg0: math.Ordering[K]): Unit
Sort array
awith quicksort, using the Ordering on its elements.Sort array
awith quicksort, using the Ordering on its elements. This algorithm sorts in place, so no additional memory is used aside from what might be required to box individual elements during comparison. -
def
quickSort(a: Array[Float]): Unit
Sort an array of Floats using
java.util.Arrays.sort. -
def
quickSort(a: Array[Int]): Unit
Sort an array of Ints using
java.util.Arrays.sort. -
def
quickSort(a: Array[Double]): Unit
Sort an array of Doubles using
java.util.Arrays.sort. -
def
stableSort[K, M](a: Seq[K], f: (K) ⇒ M)(implicit arg0: ClassTag[K], arg1: math.Ordering[M]): Array[K]
A sorted Array, given an extraction function
fthat returns an ordered key for each item in the sequencea.A sorted Array, given an extraction function
fthat returns an ordered key for each item in the sequencea. Usesjava.util.Arrays.sortunlessKis a primitive type. -
def
stableSort[K](a: Seq[K], f: (K, K) ⇒ Boolean)(implicit arg0: ClassTag[K]): Array[K]
A sorted Array, given a function
fthat computes the less-than relation for each item in the sequencea.A sorted Array, given a function
fthat computes the less-than relation for each item in the sequencea. Usesjava.util.Arrays.sortunlessKis a primitive type. -
def
stableSort[K](a: Seq[K])(implicit arg0: ClassTag[K], arg1: math.Ordering[K]): Array[K]
A sorted Array, using the Ordering for the elements in the sequence
a.A sorted Array, using the Ordering for the elements in the sequence
a. Usesjava.util.Arrays.sortunlessKis a primitive type. -
def
stableSort[K](a: Array[K], f: (K, K) ⇒ Boolean)(implicit arg0: ClassTag[K]): Unit
Sort array
ausing functionfthat computes the less-than relation for each element.Sort array
ausing functionfthat computes the less-than relation for each element. Usesjava.util.Arrays.sortunlessKis a primitive type. -
def
stableSort[K](a: Array[K])(implicit arg0: ClassTag[K], arg1: math.Ordering[K]): Unit
Sort array
ausing the Ordering on its elements, preserving the original ordering where possible.Sort array
ausing the Ordering on its elements, preserving the original ordering where possible. Usesjava.util.Arrays.sortunlessKis a primitive type. -
final
def
synchronized[T0](arg0: ⇒ T0): T0
- Definition Classes
- AnyRef
-
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
-
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
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.