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.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.collection.parallel - Parallel collections (scala-parallel-collections.jar)
  • scala.util.parsing - Parser combinators (scala-parser-combinators.jar)
  • scala.swing - A convenient wrapper around Java's GUI framework called Swing (scala-swing.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 jdk

  The jdk package contains utilities to interact with JDK classes.

  The jdk package contains utilities to interact with JDK classes.

  This packages offers a number of converters, that are able to wrap or copy types from the scala library to equivalent types in the JDK class library and vice versa:

  • CollectionConverters, converting collections like scala.collection.Seq, scala.collection.Map, scala.collection.Set, scala.collection.mutable.Buffer, scala.collection.Iterator and scala.collection.Iterable to their JDK counterparts
  • OptionConverters, converting between Option and java.util.Optional and primitive variations
  • StreamConverters, to create JDK Streams from scala collections
  • DurationConverters, for conversions between scala scala.concurrent.duration.FiniteDuration and java.time.Duration
  • FunctionConverters, from scala Functions to java java.util.function.Function, java.util.function.UnaryOperator, java.util.function.Consumer and java.util.function.Predicate, as well as primitive variations and Bi-variations.

  By convention, converters that wrap an object to provide a different interface to the same underlying data structure use .asScala and .asJava extension methods, whereas converters that copy the underlying data structure use .toScala and .toJava.

  In the javaapi package, the same converters can be found with a java-friendly interface that don't rely on implicit enrichments.

  Additionally, this package offers Accumulators, capable of efficiently traversing JDK Streams.

  Definition Classes

  scala

•  object OptionConverters

  This object provides extension methods that convert between Scala Option and Java Optional types.

  This object provides extension methods that convert between Scala Option and Java Optional types.

  When writing Java code, use the explicit conversion methods defined in javaapi.OptionConverters instead.

  Scala Option is extended with a toJava method that creates a corresponding Optional, and a toJavaPrimitive method that creates a specialized variant (e.g., OptionalInt) if applicable.

  Java Optional is extended with a toScala method and a toJavaPrimitive method.

  Finally, specialized Optional types are extended with toScala and toJavaGeneric methods.

  Example usage:

  import scala.jdk.OptionConverters._
  val a = Option("example").toJava      // Creates java.util.Optional[String] containing "example"
  val b = (None: Option[String]).toJava // Creates an empty java.util.Optional[String]
  val c = a.toScala                     // Back to Option("example")
  val d = b.toScala                     // Back to None typed as Option[String]
  val e = Option(2.7).toJava            // java.util.Optional[Double] containing boxed 2.7
  val f = Option(2.7).toJavaPrimitive   // java.util.OptionalDouble containing 2.7 (not boxed)
  val g = f.toScala                     // Back to Option(2.7)
  val h = f.toJavaGeneric               // Same as e
  val i = e.toJavaPrimitive             // Same as f

  Definition Classes

  jdk

• RichOption
• RichOptional
• RichOptionalDouble
• RichOptionalInt
• RichOptionalLong

scala.jdk.OptionConverters

RichOptionalDouble