Scala Standard Library2.12.21 < 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.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 (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
-  object Predef extends LowPriorityImplicits with DeprecatedPredef

  The `Predef` object provides definitions that are accessible in all Scala compilation units without explicit qualification.

  The `Predef` object provides definitions that are accessible in all Scala compilation units without explicit qualification.

  ##### Commonly Used Types

  Predef provides type aliases for types which are commonly used, such as the immutable collection types scala.collection.immutable.Map, scala.collection.immutable.Set, and the scala.collection.immutable.List constructors (scala.collection.immutable.:: and scala.collection.immutable.Nil).

  ##### Console Output

  For basic console output, `Predef` provides convenience methods print and println, which are aliases of the methods in the object scala.Console.

  ##### Assertions

  A set of `assert` functions are provided for use as a way to document and dynamically check invariants in code. Invocations of `assert` can be elided at compile time by providing the command line option `-Xdisable-assertions`, which raises `-Xelide-below` above `elidable.ASSERTION`, to the `scalac` command.

  Variants of `assert` intended for use with static analysis tools are also provided: `assume`, `require` and `ensuring`. `require` and `ensuring` are intended for use as a means of design-by-contract style specification of pre- and post-conditions on functions, with the intention that these specifications could be consumed by a static analysis tool. For instance,

      def addNaturals(nats: List[Int]): Int = {
        require(nats forall (_ >= 0), "List contains negative numbers")
        nats.foldLeft(0)(_ + _)
      } ensuring(_ >= 0)

  The declaration of `addNaturals` states that the list of integers passed should only contain natural numbers (i.e. non-negative), and that the result returned will also be natural. `require` is distinct from `assert` in that if the condition fails, then the caller of the function is to blame rather than a logical error having been made within `addNaturals` itself. `ensuring` is a form of `assert` that declares the guarantee the function is providing with regards to its return value.

  ##### Implicit Conversions

  A number of commonly applied implicit conversions are also defined here, and in the parent type scala.LowPriorityImplicits. Implicit conversions are provided for the "widening" of numeric values, for instance, converting a Short value to a Long value as required, and to add additional higher-order functions to Array values. These are described in more detail in the documentation of scala.Array.

  Definition Classes
    scala
- <:<
- =:=
- ArrayCharSequence
- ArrowAssoc
- DummyImplicit
- Ensuring
- Pair
- RichException
- SeqCharSequence
- StringFormat
- Triple
- any2stringadd

c

scala.Predef

# StringFormat 

###

#### implicit final class StringFormat[A] extends AnyVal

Source
  Predef.scala

Linear Supertypes
AnyVal, Any
 
Ordering

1. Alphabetic
2. By Inheritance

Inherited

1. StringFormat
2. AnyVal
3. Any

Implicitly

1. by any2stringadd
2. by Ensuring
3. by ArrowAssoc
4. by any2stringadd
5. by Ensuring
6. by ArrowAssoc

1. Hide All
2. Show All

Visibility

1. Public
2. All

### Instance Constructors

1.  new StringFormat(self: A)

### 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
     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
     Any
3.  final def ==(arg0: Any): Boolean

   Test two objects for equality.

   Test two objects for equality. 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
     Any
4.  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 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 type `T0`.

5.  def getClass(): Class[_ <: AnyVal]

   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
     AnyVal → Any
6.  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 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 type `T0`; `false` otherwise.

   Definition Classes
     Any
7.  def toString(): java.lang.String

   Returns a string representation of the object.

   Returns a string representation of the object.

   The default representation is platform dependent.

   returns

     a string representation of the object.

   Definition Classes
     Any

### Shadowed Implicit Value Members

1.  def +(other: String): String
   Implicit
     This member is added by an implicit conversion from StringFormat[A] to any2stringadd[StringFormat[A]] performed by method any2stringadd in scala.Predef.
   Shadowing
     This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
     To access this member you can use a type ascription:

         (stringFormat: any2stringadd[StringFormat[A]]).+(other)

   Definition Classes
     any2stringadd
2.  def +(other: String): String
   Implicit
     This member is added by an implicit conversion from StringFormat[A] to any2stringadd[StringFormat[A]] performed by method any2stringadd in scala.Predef.
   Shadowing
     This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
     To access this member you can use a type ascription:

         (stringFormat: any2stringadd[StringFormat[A]]).+(other)

   Definition Classes
     any2stringadd
3.  def ->[B](y: B): (StringFormat[A], B)
   Implicit
     This member is added by an implicit conversion from StringFormat[A] to ArrowAssoc[StringFormat[A]] performed by method ArrowAssoc in scala.Predef.
   Shadowing
     This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
     To access this member you can use a type ascription:

         (stringFormat: ArrowAssoc[StringFormat[A]]).->(y)

   Definition Classes
     ArrowAssoc
   Annotations
     @inline()
4.  def ->[B](y: B): (StringFormat[A], B)
   Implicit
     This member is added by an implicit conversion from StringFormat[A] to ArrowAssoc[StringFormat[A]] performed by method ArrowAssoc in scala.Predef.
   Shadowing
     This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
     To access this member you can use a type ascription:

         (stringFormat: ArrowAssoc[StringFormat[A]]).->(y)

   Definition Classes
     ArrowAssoc
   Annotations
     @inline()
5.  def ensuring(cond: (StringFormat[A]) ⇒ Boolean, msg: ⇒ Any): StringFormat[A]
   Implicit
     This member is added by an implicit conversion from StringFormat[A] to Ensuring[StringFormat[A]] performed by method Ensuring in scala.Predef.
   Shadowing
     This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
     To access this member you can use a type ascription:

         (stringFormat: Ensuring[StringFormat[A]]).ensuring(cond, msg)

   Definition Classes
     Ensuring
6.  def ensuring(cond: (StringFormat[A]) ⇒ Boolean): StringFormat[A]
   Implicit
     This member is added by an implicit conversion from StringFormat[A] to Ensuring[StringFormat[A]] performed by method Ensuring in scala.Predef.
   Shadowing
     This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
     To access this member you can use a type ascription:

         (stringFormat: Ensuring[StringFormat[A]]).ensuring(cond)

   Definition Classes
     Ensuring
7.  def ensuring(cond: Boolean, msg: ⇒ Any): StringFormat[A]
   Implicit
     This member is added by an implicit conversion from StringFormat[A] to Ensuring[StringFormat[A]] performed by method Ensuring in scala.Predef.
   Shadowing
     This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
     To access this member you can use a type ascription:

         (stringFormat: Ensuring[StringFormat[A]]).ensuring(cond, msg)

   Definition Classes
     Ensuring
8.  def ensuring(cond: Boolean): StringFormat[A]
   Implicit
     This member is added by an implicit conversion from StringFormat[A] to Ensuring[StringFormat[A]] performed by method Ensuring in scala.Predef.
   Shadowing
     This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
     To access this member you can use a type ascription:

         (stringFormat: Ensuring[StringFormat[A]]).ensuring(cond)

   Definition Classes
     Ensuring
9.  def ensuring(cond: (StringFormat[A]) ⇒ Boolean, msg: ⇒ Any): StringFormat[A]
   Implicit
     This member is added by an implicit conversion from StringFormat[A] to Ensuring[StringFormat[A]] performed by method Ensuring in scala.Predef.
   Shadowing
     This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
     To access this member you can use a type ascription:

         (stringFormat: Ensuring[StringFormat[A]]).ensuring(cond, msg)

   Definition Classes
     Ensuring
10.  def ensuring(cond: (StringFormat[A]) ⇒ Boolean): StringFormat[A]
    Implicit
      This member is added by an implicit conversion from StringFormat[A] to Ensuring[StringFormat[A]] performed by method Ensuring in scala.Predef.
    Shadowing
      This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
      To access this member you can use a type ascription:

          (stringFormat: Ensuring[StringFormat[A]]).ensuring(cond)

    Definition Classes
      Ensuring
11.  def ensuring(cond: Boolean, msg: ⇒ Any): StringFormat[A]
    Implicit
      This member is added by an implicit conversion from StringFormat[A] to Ensuring[StringFormat[A]] performed by method Ensuring in scala.Predef.
    Shadowing
      This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
      To access this member you can use a type ascription:

          (stringFormat: Ensuring[StringFormat[A]]).ensuring(cond, msg)

    Definition Classes
      Ensuring
12.  def ensuring(cond: Boolean): StringFormat[A]
    Implicit
      This member is added by an implicit conversion from StringFormat[A] to Ensuring[StringFormat[A]] performed by method Ensuring in scala.Predef.
    Shadowing
      This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
      To access this member you can use a type ascription:

          (stringFormat: Ensuring[StringFormat[A]]).ensuring(cond)

    Definition Classes
      Ensuring
13.  def →[B](y: B): (StringFormat[A], B)
    Implicit
      This member is added by an implicit conversion from StringFormat[A] to ArrowAssoc[StringFormat[A]] performed by method ArrowAssoc in scala.Predef.
    Shadowing
      This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
      To access this member you can use a type ascription:

          (stringFormat: ArrowAssoc[StringFormat[A]]).→(y)

    Definition Classes
      ArrowAssoc
14.  def →[B](y: B): (StringFormat[A], B)
    Implicit
      This member is added by an implicit conversion from StringFormat[A] to ArrowAssoc[StringFormat[A]] performed by method ArrowAssoc in scala.Predef.
    Shadowing
      This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
      To access this member you can use a type ascription:

          (stringFormat: ArrowAssoc[StringFormat[A]]).→(y)

    Definition Classes
      ArrowAssoc

### 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).

   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.

### Inherited from AnyVal

### Inherited from Any

### Inherited by implicit conversion any2stringadd from StringFormat[A] to any2stringadd[StringFormat[A]]

### Inherited by implicit conversion Ensuring from StringFormat[A] to Ensuring[StringFormat[A]]

### Inherited by implicit conversion ArrowAssoc from StringFormat[A] to ArrowAssoc[StringFormat[A]]

### Inherited by implicit conversion any2stringadd from StringFormat[A] to any2stringadd[StringFormat[A]]

### Inherited by implicit conversion Ensuring from StringFormat[A] to Ensuring[StringFormat[A]]

### Inherited by implicit conversion ArrowAssoc from StringFormat[A] to ArrowAssoc[StringFormat[A]]

### Ungrouped