Scala Standard Library2.13.17 < Back
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# 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 util
  Definition Classes
    scala
-  package control
  Definition Classes
    util
-  package hashing
  Definition Classes
    util
-  package matching
  Definition Classes
    util
- ChainingOps
- ChainingSyntax
- DynamicVariable
- Either
- Failure
- Left
- Properties
- Random
- Right
- Sorting
- Success
- Try
- Using
- chaining

c

scala.util

# Either

###
Companion object Either

#### sealed abstract class Either[+A, +B] extends Product with Serializable

Represents a value of one of two possible types (a disjoint union). An instance of `Either` is an instance of either scala.util.Left or scala.util.Right.

A common use of `Either` is as an alternative to scala.Option for dealing with possibly missing values. In this usage, scala.None is replaced with a scala.util.Left which can contain useful information. scala.util.Right takes the place of scala.Some. Convention dictates that `Left` is used for failure and `Right` is used for success.

For example, you could use `Either[String, Int]` to indicate whether a received input is a `String` or an `Int`.

    import scala.io.StdIn._
    val in = readLine("Type Either a string or an Int: ")
    val result: Either[String,Int] =
      try Right(in.toInt)
      catch {
        case e: NumberFormatException => Left(in)
      }

    result match {
      case Right(x) => s"You passed me the Int: $x, which I will increment. $x + 1 = ${x+1}"
      case Left(x)  => s"You passed me the String: $x"
    }

`Either` is right-biased, which means that `Right` is assumed to be the default case to operate on. If it is `Left`, operations like `map` and `flatMap` return the `Left` value unchanged:

    def doubled(i: Int) = i * 2
    Right(42).map(doubled) // Right(84)
    Left(42).map(doubled)  // Left(42)

Since `Either` defines the methods `map` and `flatMap`, it can also be used in for comprehensions:

    val right1 = Right(1)   : Right[Double, Int]
    val right2 = Right(2)
    val right3 = Right(3)
    val left23 = Left(23.0) : Left[Double, Int]
    val left42 = Left(42.0)

    for {
      x <- right1
      y <- right2
      z <- right3
    } yield x + y + z // Right(6)

    for {
      x <- right1
      y <- right2
      z <- left23
    } yield x + y + z // Left(23.0)

    for {
      x <- right1
      y <- left23
      z <- right2
    } yield x + y + z // Left(23.0)

    // Guard expressions are not supported:
    for {
      i <- right1
      if i > 0
    } yield i
    // error: value withFilter is not a member of Right[Double,Int]

    // Similarly, refutable patterns are not supported:
    for (x: Int <- right1) yield x
    // error: value withFilter is not a member of Right[Double,Int]

    // To use a filtered value, convert to an Option first,
    // which drops the Left case, as None contains no value:
    for {
      i <- right1.toOption
      if i > 0
    } yield i

Since `for` comprehensions use `map` and `flatMap`, the types of function parameters used in the expression must be inferred. These types are constrained by the `Either` values. In particular, because of right-biasing, `Left` values may require an explicit type argument for type parameter `B`, the right value. Otherwise, it might be inferred as `Nothing`.

    for {
      x <- left23
      y <- right1
      z <- left42  // type at this position: Either[Double, Nothing]
    } yield x + y + z
    //            ^
    // error: ambiguous reference to overloaded definition,
    // both method + in class Int of type (x: Char)Int
    // and  method + in class Int of type (x: Byte)Int
    // match argument types (Nothing)

    for (x <- right2 ; y <- left23) yield x + y  // Left(23.0)
    for (x <- right2 ; y <- left42) yield x + y  // error

    for {
      x <- right1
      y <- left42  // type at this position: Either[Double, Nothing]
      z <- left23
    } yield x + y + z
    // Left(42.0), but unexpectedly a `Either[Double,String]`

Source
  Either.scala

Linear Supertypes
java.io.Serializable, Product, Equals, AnyRef, Any
Known Subclasses
Left, Right
Type Hierarchy

Ordering

1. Alphabetic
2. By Inheritance

Inherited

1. Either
2. Serializable
3. Product
4. Equals
5. AnyRef
6. Any

Implicitly

1. by MergeableEither
2. by any2stringadd
3. by StringFormat
4. by Ensuring
5. by ArrowAssoc

1. Hide All
2. Show All

Visibility

1. Public
2. Protected

### Abstract Value Members

1.  abstract def canEqual(that: Any): Boolean

   Checks whether this instance can possibly equal `that`.

   Checks whether this instance can possibly equal `that`.

   A method that should be called from every well-designed equals method that is open to be overridden in a subclass. See Programming in Scala, Chapter 28 for discussion and design.

   that

     the value being probed for possible equality

   returns

     true if this instance can possibly equal `that`, otherwise false

   Definition Classes
     Equals
2.  abstract def isLeft: Boolean

   Returns `true` if this is a `Left`, `false` otherwise.

   Returns `true` if this is a `Left`, `false` otherwise.

       Left("tulip").isLeft // true
       Right("venus fly-trap").isLeft // false

3.  abstract def isRight: Boolean

   Returns `true` if this is a `Right`, `false` otherwise.

   Returns `true` if this is a `Right`, `false` otherwise.

       Left("tulip").isRight // false
       Right("venus fly-trap").isRight // true

4.  abstract def productArity: Int

   The size of this product.

   The size of this product.

   returns

     for a product `A(x1, ..., xk)`, returns `k`

   Definition Classes
     Product
5.  abstract def productElement(n: Int): Any

   The nth element of this product, 0-based.

   The nth element of this product, 0-based. In other words, for a product `A(x1, ..., xk)`, returns `x(n+1)` where `0 <= n < k`.

   n

     the index of the element to return

   returns

     the element `n` elements after the first element

   Definition Classes
     Product
   Exceptions thrown

     `IndexOutOfBoundsException` if the `n` is out of range(n < 0 || n >= productArity).

### Concrete Value Members

1.  final def !=(arg0: Any): Boolean

   Test two objects for inequality.

   Test two objects for inequality.

   returns

     `true` if !(this == that), false otherwise.

   Definition Classes
     AnyRef → Any
2.  final def ##: Int

   Equivalent to `x.hashCode` except for boxed numeric types and `null`.

   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
3.  def +(other: String): String
   Implicit
     This member is added by an implicit conversion from Either[A, B] toany2stringadd[Either[A, B]] performed by method any2stringadd in scala.Predef.
   Definition Classes
     any2stringadd
4.  def ->[B](y: B): (Either[A, B], B)
   Implicit
     This member is added by an implicit conversion from Either[A, B] toArrowAssoc[Either[A, B]] performed by method ArrowAssoc in scala.Predef.
   Definition Classes
     ArrowAssoc
   Annotations
     @inline()
5.  final def ==(arg0: Any): Boolean

   The expression `x == that` is equivalent to `if (x eq null) that eq null else x.equals(that)`.

   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
6.  final def asInstanceOf[T0]: T0

   Forces the compiler to treat the receiver object as having type `T0`, even though doing so may violate type safety.

   Forces the compiler to treat the receiver object as having type `T0`, even though doing so may violate type safety.

   This method is useful when you believe you have type information the compiler doesn't, and it also isn't possible to check the type at runtime. In such situations, skipping type safety is the only option.

   It is platform dependent whether `asInstanceOf` has any effect at runtime. It might do a runtime type test on the erasure of `T0`, insert a conversion (such as boxing/unboxing), fill in a default value, or do nothing at all.

   In particular, `asInstanceOf` is not a type test. It does **not** mean:

       this match {
        case x: T0 => x
        case _     => throw ClassCastException("...")

   Use pattern matching or isInstanceOf for type testing instead.

   Situations where `asInstanceOf` is useful:

   - when flow analysis fails to deduce `T0` automatically
   - when down-casting a type parameter or an abstract type member (which cannot be checked at runtime due to type erasure) If there is any doubt and you are able to type test instead, you should do so.

   Be careful of using `asInstanceOf` when `T0` is a primitive type. When `T0` is primitive, `asInstanceOf` may insert a conversion instead of a type test. If your intent is to convert, use a `toT` method (`x.toChar`, `x.toByte`, etc.).

   returns

     the receiver object.

   Definition Classes
     Any
   Exceptions thrown

     `ClassCastException` if the receiver is not an instance of the erasure of `T0`, if that can be checked on this platform

7.  def clone(): AnyRef

   Create a copy of the receiver object.

   Create a copy of the receiver object.

   The default implementation of the `clone` method is platform dependent.

   returns

     a copy of the receiver object.

   Attributes
     protected[lang]
   Definition Classes
     AnyRef
   Annotations
     @throws(classOf[java.lang.CloneNotSupportedException]) @native()
   Note

     not specified by SLS as a member of AnyRef

8.  final def contains[B1 >: B](elem: B1): Boolean

   Returns `true` if this is a `Right` and its value is equal to `elem` (as determined by `==`), returns `false` otherwise.

   Returns `true` if this is a `Right` and its value is equal to `elem` (as determined by `==`), returns `false` otherwise.

       // Returns true because value of Right is "something" which equals "something".
       Right("something") contains "something"

       // Returns false because value of Right is "something" which does not equal "anything".
       Right("something") contains "anything"

       // Returns false because it's not a Right value.
       Left("something") contains "something"

   elem

     the element to test.

   returns

     `true` if this is a `Right` value equal to `elem`.

9.  def ensuring(cond: (Either[A, B]) => Boolean, msg: => Any): Either[A, B]
   Implicit
     This member is added by an implicit conversion from Either[A, B] toEnsuring[Either[A, B]] performed by method Ensuring in scala.Predef.
   Definition Classes
     Ensuring
10.  def ensuring(cond: (Either[A, B]) => Boolean): Either[A, B]
    Implicit
      This member is added by an implicit conversion from Either[A, B] toEnsuring[Either[A, B]] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
11.  def ensuring(cond: Boolean, msg: => Any): Either[A, B]
    Implicit
      This member is added by an implicit conversion from Either[A, B] toEnsuring[Either[A, B]] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
12.  def ensuring(cond: Boolean): Either[A, B]
    Implicit
      This member is added by an implicit conversion from Either[A, B] toEnsuring[Either[A, B]] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
13.  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 `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
14.  def equals(arg0: AnyRef): Boolean

    The equality method for reference types.

    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
15.  def exists(p: (B) => Boolean): Boolean

    Returns `false` if `Left` or returns the result of the application of the given predicate to the `Right` value.

    Returns `false` if `Left` or returns the result of the application of the given predicate to the `Right` value.

        Right(12).exists(_ > 10)   // true
        Right(7).exists(_ > 10)    // false
        Left(12).exists(_ => true) // false

16.  def filterOrElse[A1 >: A](p: (B) => Boolean, zero: => A1): Either[A1, B]

    Returns `Right` with the existing value of `Right` if this is a `Right` and the given predicate `p` holds for the right value, or `Left(zero)` if this is a `Right` and the given predicate `p` does not hold for the right value, or `Left` with the existing value of `Left` if this is a `Left`.

    Returns `Right` with the existing value of `Right` if this is a `Right` and the given predicate `p` holds for the right value, or `Left(zero)` if this is a `Right` and the given predicate `p` does not hold for the right value, or `Left` with the existing value of `Left` if this is a `Left`.

        Right(12).filterOrElse(_ > 10, -1)   // Right(12)
        Right(7).filterOrElse(_ > 10, -1)    // Left(-1)
        Left(7).filterOrElse(_ => false, -1) // Left(7)

17.  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 `finalize` method is invoked, as well as the interaction between `finalize` and non-local returns and exceptions, are all platform dependent.

    Attributes
      protected[lang]
    Definition Classes
      AnyRef
    Annotations
      @throws(classOf[java.lang.Throwable])
    Note

      not specified by SLS as a member of AnyRef

18.  def flatMap[A1 >: A, B1](f: (B) => Either[A1, B1]): Either[A1, B1]

    Binds the given function across `Right`.

    Binds the given function across `Right`.

    f

      The function to bind across `Right`.

19.  def flatten[A1 >: A, B1](implicit ev: <:<[B, Either[A1, B1]]): Either[A1, B1]

    Returns the right value if this is right or this value if this is left

    Returns the right value if this is right or this value if this is left

    Example:

    1.     val  l: Either[String, Either[String, Int]] = Left("pancake")
           val rl: Either[String, Either[String, Int]] = Right(Left("flounder"))
           val rr: Either[String, Either[String, Int]] = Right(Right(7))

            l.flatten //Either[String, Int]: Left("pancake")
           rl.flatten //Either[String, Int]: Left("flounder")
           rr.flatten //Either[String, Int]: Right(7)

       Equivalent to `flatMap(id => id)`

20.  def fold[C](fa: (A) => C, fb: (B) => C): C

    Applies `fa` if this is a `Left` or `fb` if this is a `Right`.

    Applies `fa` if this is a `Left` or `fb` if this is a `Right`.

    fa

      the function to apply if this is a `Left`

    fb

      the function to apply if this is a `Right`

    returns

      the results of applying the function

    Example:

    1.     val result = util.Try("42".toInt).toEither
           result.fold(
             e => s"Operation failed with $e",
             v => s"Operation produced value: $v"
           )

21.  def forall(f: (B) => Boolean): Boolean

    Returns `true` if `Left` or returns the result of the application of the given predicate to the `Right` value.

    Returns `true` if `Left` or returns the result of the application of the given predicate to the `Right` value.

        Right(12).forall(_ > 10)    // true
        Right(7).forall(_ > 10)     // false
        Left(12).forall(_ => false) // true

22.  def foreach[U](f: (B) => U): Unit

    Executes the given side-effecting function if this is a `Right`.

    Executes the given side-effecting function if this is a `Right`.

        Right(12).foreach(println) // prints "12"
        Left(12).foreach(println)  // doesn't print

    f

      The side-effecting function to execute.

23.  final def getClass(): Class[_ <: AnyRef]

    Returns the runtime class representation of the object.

    Returns the runtime class representation of the object.

    returns

      a class object corresponding to the runtime type of the receiver.

    Definition Classes
      AnyRef → Any
    Annotations
      @native()
24.  def getOrElse[B1 >: B](or: => B1): B1

    Returns the value from this `Right` or the given argument if this is a `Left`.

    Returns the value from this `Right` or the given argument if this is a `Left`.

        Right(12).getOrElse(17) // 12
        Left(12).getOrElse(17)  // 17

25.  def hashCode(): Int

    The hashCode method for reference types.

    The hashCode method for reference types. See hashCode in scala.Any.

    returns

      the hash code value for this object.

    Definition Classes
      AnyRef → Any
    Annotations
      @native()
26.  final def isInstanceOf[T0]: Boolean

    Test whether the dynamic type of the receiver object has the same erasure as `T0`.

    Test whether the dynamic type of the receiver object has the same erasure as `T0`.

    Depending on what `T0` is, the test is done in one of the below ways:

    - `T0` is a non-parameterized class type, e.g. `BigDecimal`: this method returns `true` if the value of the receiver object is a `BigDecimal` or a subtype of `BigDecimal`.
    - `T0` is a parameterized class type, e.g. `List[Int]`: this method returns `true` if the value of the receiver object is some `List[X]` for any `X`. For example, `List(1, 2, 3).isInstanceOf[List[String]]` will return true.
    - `T0` is some singleton type `x.type` or literal `x`: this method returns `this.eq(x)`. For example, `x.isInstanceOf[1]` is equivalent to `x.eq(1)`
    - `T0` is an intersection `X with Y` or `X & Y: this method is equivalent to` x.isInstanceOf[X] && x.isInstanceOf[Y]``
    - `T0` is a union `X | Y`: this method is equivalent to `x.isInstanceOf[X] || x.isInstanceOf[Y]`
    - `T0` is a type parameter or an abstract type member: this method is equivalent to `isInstanceOf[U]` where `U` is `T0`'s upper bound, `Any` if `T0` is unbounded. For example, `x.isInstanceOf[A]` where `A` is an unbounded type parameter will return true for any value of `x`.

    This is exactly equivalent to the type pattern `_: T0`

    returns

      `true` if the receiver object is an instance of erasure of type `T0`; `false` otherwise.

    Definition Classes
      Any
    Note

      due to the unexpectedness of `List(1, 2, 3).isInstanceOf[List[String]]` returning true and `x.isInstanceOf[A]` where `A` is a type parameter or abstract member returning true, these forms issue a warning.

27.  def joinLeft[A1 >: A, B1 >: B, C](implicit ev: <:<[A1, Either[C, B1]]): Either[C, B1]

    Joins an `Either` through `Left`.

    Joins an `Either` through `Left`.

    This method requires that the left side of this `Either` is itself an `Either` type. That is, this must be some type like:

        Either[Either[C, B], B]

    (which respects the type parameter bounds, shown below.)

    If this instance is a `Left[Either[C, B]]` then the contained `Either[C, B]` will be returned, otherwise this value will be returned unmodified.

        Left[Either[Int, String], String](Right("flower")).joinLeft // Result: Right("flower")
        Left[Either[Int, String], String](Left(12)).joinLeft // Result: Left(12)
        Right[Either[Int, String], String]("daisy").joinLeft // Result: Right("daisy")

    This method, and `joinRight`, are analogous to `Option#flatten`.

28.  def joinRight[A1 >: A, B1 >: B, C](implicit ev: <:<[B1, Either[A1, C]]): Either[A1, C]

    Joins an `Either` through `Right`.

    Joins an `Either` through `Right`.

    This method requires that the right side of this `Either` is itself an `Either` type. That is, this must be some type like:

        Either[A, Either[A, C]]

    (which respects the type parameter bounds, shown below.)

    If this instance is a `Right[Either[A, C]]` then the contained `Either[A, C]` will be returned, otherwise this value will be returned unmodified.

    Example:

    1.     Right[String, Either[String, Int]](Right(12)).joinRight // Result: Right(12)
           Right[String, Either[String, Int]](Left("flower")).joinRight // Result: Left("flower")
           Left[String, Either[String, Int]]("flower").joinRight // Result: Left("flower")

       This method, and `joinLeft`, are analogous to `Option#flatten`

29.  def left: LeftProjection[A, B]

    Projects this `Either` as a `Left`.

    Projects this `Either` as a `Left`.

    This allows for-comprehensions over the left side of `Either` instances, reversing `Either`'s usual right-bias.

    For example

        for (s <- Left("flower").left) yield s.length // Left(6)

    Continuing the analogy with scala.Option, a `LeftProjection` declares that `Left` should be analogous to `Some` in some code.

        // using Option
        def interactWithDB(x: Query): Option[Result] =
          try Some(getResultFromDatabase(x))
          catch {
            case _: SQLException => None
          }

        // this will only be executed if interactWithDB returns a Some
        val report = for (result <- interactWithDB(someQuery)) yield generateReport(result)
        report match {
          case Some(r) => send(r)
          case None    => log("report not generated, not sure why...")
        }

        // using Either
        def interactWithDB(x: Query): Either[Exception, Result] =
          try Right(getResultFromDatabase(x))
          catch {
            case e: SQLException => Left(e)
          }

         // run a report only if interactWithDB returns a Right
         val report = for (result <- interactWithDB(someQuery)) yield generateReport(result)
         report match {
           case Right(r) => send(r)
           case Left(e)  => log(s"report not generated, reason was $e")
         }
         // only report errors
         for (e <- interactWithDB(someQuery).left) log(s"query failed, reason was $e")

30.  def map[B1](f: (B) => B1): Either[A, B1]

    The given function is applied if this is a `Right`.

    The given function is applied if this is a `Right`.

        Right(12).map(x => "flower") // Result: Right("flower")
        Left(12).map(x => "flower")  // Result: Left(12)

31.  def merge: B
    Implicit
      This member is added by an implicit conversion from Either[A, B] toMergeableEither[B] performed by method MergeableEither in scala.util.Either.This conversion will take place only if B is a superclass of A (B >: A).
    Definition Classes
      MergeableEither
32.  final def ne(arg0: AnyRef): Boolean

    Equivalent to `!(this eq that)`.

    Equivalent to `!(this eq that)`.

    returns

      `true` if the argument is not a reference to the receiver object; `false` otherwise.

    Definition Classes
      AnyRef
33.  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

34.  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

35.  def orElse[A1 >: A, B1 >: B](or: => Either[A1, B1]): Either[A1, B1]

    Returns this `Right` or the given argument if this is a `Left`.

    Returns this `Right` or the given argument if this is a `Left`.

        Right(1) orElse Left(2) // Right(1)
        Left(1) orElse Left(2)  // Left(2)
        Left(1) orElse Left(2) orElse Right(3) // Right(3)

36.  def productElementName(n: Int): String

    The name of the nth element of this product, 0-based.

    The name of the nth element of this product, 0-based. In the default implementation, an empty string.

    n

      the index of the element name to return

    returns

      the name of the specified element

    Definition Classes
      Product
    Exceptions thrown

      `IndexOutOfBoundsException` if the `n` is out of range(n < 0 || n >= productArity).

37.  def productElementNames: Iterator[String]

    An iterator over the names of all the elements of this product.

    An iterator over the names of all the elements of this product.

    Definition Classes
      Product
38.  def productIterator: Iterator[Any]

    An iterator over all the elements of this product.

    An iterator over all the elements of this product.

    returns

      in the default implementation, an `Iterator[Any]`

    Definition Classes
      Product
39.  def productPrefix: String

    A string used in the `toString` methods of derived classes.

    A string used in the `toString` methods of derived classes. Implementations may override this method to prepend a string prefix to the result of `toString` methods.

    returns

      in the default implementation, the empty string

    Definition Classes
      Product
40.  def swap: Either[B, A]

    If this is a `Left`, then return the left value in `Right` or vice versa.

    If this is a `Left`, then return the left value in `Right` or vice versa.

    Examples:

    1.     val left: Either[String, Int]  = Left("left")
           val right: Either[Int, String] = left.swap // Result: Right("left")

    ,

    2.     val right = Right(2)
           val left  = Left(3)
           for {
             r1 <- right
             r2 <- left.swap
           } yield r1 * r2 // Right(6)

41.  final def synchronized[T0](arg0: => T0): T0

    Executes the code in `body` with an exclusive lock on `this`.

    Executes the code in `body` with an exclusive lock on `this`.

    returns

      the result of `body`

    Definition Classes
      AnyRef
42.  def toOption: Option[B]

    Returns a `Some` containing the `Right` value if it exists or a `None` if this is a `Left`.

    Returns a `Some` containing the `Right` value if it exists or a `None` if this is a `Left`.

        Right(12).toOption // Some(12)
        Left(12).toOption  // None

43.  def toSeq: collection.immutable.Seq[B]

    Returns a `Seq` containing the `Right` value if it exists or an empty `Seq` if this is a `Left`.

    Returns a `Seq` containing the `Right` value if it exists or an empty `Seq` if this is a `Left`.

        Right(12).toSeq // Seq(12)
        Left(12).toSeq  // Seq()

44.  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
45.  def toTry(implicit ev: <:<[A, Throwable]): Try[B]
46.  final def wait(): Unit

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.

    Definition Classes
      AnyRef
    Annotations
      @throws(classOf[java.lang.InterruptedException])
    Note

      not specified by SLS as a member of AnyRef

47.  final def wait(arg0: Long, arg1: Int): Unit

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-

    Definition Classes
      AnyRef
    Annotations
      @throws(classOf[java.lang.InterruptedException])
    Note

      not specified by SLS as a member of AnyRef

48.  final def wait(arg0: Long): Unit

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.

    See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.

    Definition Classes
      AnyRef
    Annotations
      @throws(classOf[java.lang.InterruptedException]) @native()
    Note

      not specified by SLS as a member of AnyRef

### Deprecated Value Members

1.  def formatted(fmtstr: String): String

   Returns string formatted according to given `format` 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 Either[A, B] toStringFormat[Either[A, B]] performed by method StringFormat in scala.Predef.
   Definition Classes
     StringFormat
   Annotations
     @deprecated @inline()
   Deprecated

     (Since version 2.12.16) Use `formatString.format(value)` instead of `value.formatted(formatString)`, or use the `f""` string interpolator. In Java 15 and later, `formatted` resolves to the new method in String which has reversed parameters.

2.  def right: RightProjection[A, B]

   Projects this `Either` as a `Right`.

   Projects this `Either` as a `Right`.

   Because `Either` is right-biased, this method is not normally needed.

   Annotations
     @deprecated
   Deprecated

     (Since version 2.13.0) Either is now right-biased, use methods directly on Either

3.  def →[B](y: B): (Either[A, B], B)
   Implicit
     This member is added by an implicit conversion from Either[A, B] toArrowAssoc[Either[A, B]] performed by method ArrowAssoc in scala.Predef.
   Definition Classes
     ArrowAssoc
   Annotations
     @deprecated
   Deprecated

     (Since version 2.13.0) Use `->` instead. If you still wish to display it as one character, consider using a font with programming ligatures such as Fira Code.

### Inherited from java.io.Serializable

### Inherited from Product

### Inherited from Equals

### Inherited from AnyRef

### Inherited from Any

### Inherited by implicit conversion MergeableEither fromEither[A, B] to MergeableEither[B]

### Inherited by implicit conversion any2stringadd fromEither[A, B] to any2stringadd[Either[A, B]]

### Inherited by implicit conversion StringFormat fromEither[A, B] to StringFormat[Either[A, B]]

### Inherited by implicit conversion Ensuring fromEither[A, B] to Ensuring[Either[A, B]]

### Inherited by implicit conversion ArrowAssoc fromEither[A, B] to ArrowAssoc[Either[A, B]]

### Ungrouped