Packages

•  package root

  This is the documentation for the Scala standard library.

  This is the documentation for the Scala standard library.

  Package structure

  The scala package contains core types like Int, Float, Array or Option which are accessible in all Scala compilation units without explicit qualification or imports.

  Notable packages include:

  • scala.collection and its sub-packages contain Scala's collections framework
    • scala.collection.immutable - Immutable, sequential data-structures such as Vector, List, Range, HashMap or HashSet
    • scala.collection.mutable - Mutable, sequential data-structures such as ArrayBuffer, StringBuilder, HashMap or HashSet
    • scala.collection.concurrent - Mutable, concurrent data-structures such as TrieMap
    • scala.collection.parallel.immutable - Immutable, parallel data-structures such as ParVector, ParRange, ParHashMap or ParHashSet
    • scala.collection.parallel.mutable - Mutable, parallel data-structures such as ParArray, ParHashMap, ParTrieMap or ParHashSet
  • scala.concurrent - Primitives for concurrent programming such as Futures and Promises
  • scala.io - Input and output operations
  • scala.math - Basic math functions and additional numeric types like BigInt and BigDecimal
  • scala.sys - Interaction with other processes and the operating system
  • scala.util.matching - Regular expressions

  Other 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, including an example implementation of a JSON parser (scala-parser-combinators.jar)

  Automatic imports

  Identifiers in the scala package and the scala.Predef object are always in scope by default.

  Some of these identifiers are type aliases provided as shortcuts to commonly used classes. For example, List is an alias for scala.collection.immutable.List.

  Other aliases refer to classes provided by the underlying platform. For example, on the JVM, String is an alias for java.lang.String.

  Definition Classes

  root

•  package scala

  Core Scala types.

  Core Scala types. They are always available without an explicit import.

  Definition Classes

  root

•  package annotation

  Definition Classes

  scala

•  package meta

  When defining a field, the Scala compiler creates up to four accessors for it: a getter, a setter, and if the field is annotated with @BeanProperty, a bean getter and a bean setter.

  When defining a field, the Scala compiler creates up to four accessors for it: a getter, a setter, and if the field is annotated with @BeanProperty, a bean getter and a bean setter.

  For instance in the following class definition

  class C(@myAnnot @BeanProperty var c: Int)

  there are six entities which can carry the annotation @myAnnot: the constructor parameter, the generated field and the four accessors.

  By default, annotations on (val-, var- or plain) constructor parameters end up on the parameter, not on any other entity. Annotations on fields by default only end up on the field.

  The meta-annotations in package scala.annotation.meta are used to control where annotations on fields and class parameters are copied. This is done by annotating either the annotation type or the annotation class with one or several of the meta-annotations in this package.

  Annotating the annotation type

  The target meta-annotations can be put on the annotation type when instantiating the annotation. In the following example, the annotation @Id will be added only to the bean getter getX.

  import javax.persistence.Id
  class A {
    @(Id @beanGetter) @BeanProperty val x = 0
  }

  In order to annotate the field as well, the meta-annotation @field would need to be added.

  The syntax can be improved using a type alias:

  object ScalaJPA {
    type Id = javax.persistence.Id @beanGetter
  }
  import ScalaJPA.Id
  class A {
    @Id @BeanProperty val x = 0
  }

  Annotating the annotation class

  For annotations defined in Scala, a default target can be specified in the annotation class itself, for example

  @getter
  class myAnnotation extends Annotation

  This only changes the default target for the annotation myAnnotation. When instantiating the annotation, the target can still be specified as described in the last section.

  Definition Classes

  annotation

•  package unchecked

  Definition Classes

  annotation

• uncheckedStable
• uncheckedVariance

scala.annotation

unchecked 