case class StringContext(parts: String*) extends Product with Serializable
This class provides the basic mechanism to do String Interpolation. String Interpolation allows users to embed variable references directly in *processed* string literals. Here's an example:
val name = "James" println(s"Hello, $name") // Hello, James
Any processed string literal is rewritten as an instantiation and method call against this class. For example:
s"Hello, $name"
is rewritten to be:
StringContext("Hello, ", "").s(name)
By default, this class provides the raw
, s
and f
methods as
available interpolators.
To provide your own string interpolator, create an implicit class
which adds a method to StringContext
. Here's an example:
implicit class JsonHelper(private val sc: StringContext) extends AnyVal { def json(args: Any*): JSONObject = ... } val x: JSONObject = json"{ a: $a }"
Here the JsonHelper
extension class implicitly adds the json
method to
StringContext
which can be used for json
string literals.
- parts
The parts that make up the interpolated string, without the expressions that get inserted by interpolation.
- Source
- StringContext.scala
- Alphabetic
- By Inheritance
- StringContext
- Serializable
- Product
- Equals
- AnyRef
- Any
- by any2stringadd
- by StringFormat
- by Ensuring
- by ArrowAssoc
- Hide All
- Show All
- Public
- Protected
Instance Constructors
Value Members
- 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
- final def ##: Int
Equivalent to
x.hashCode
except for boxed numeric types andnull
.Equivalent to
x.hashCode
except 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. Fornull
returns a hashcode wherenull.hashCode
throws aNullPointerException
.- returns
a hash value consistent with ==
- Definition Classes
- AnyRef → Any
- def +(other: String): String
- Implicit
- This member is added by an implicit conversion from StringContext toany2stringadd[StringContext] performed by method any2stringadd in scala.Predef.
- Definition Classes
- any2stringadd
- def ->[B](y: B): (StringContext, B)
- Implicit
- This member is added by an implicit conversion from StringContext toArrowAssoc[StringContext] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
- Annotations
- @inline()
- final def ==(arg0: Any): Boolean
The expression
x == that
is equivalent toif (x eq null) that eq null else x.equals(that)
.The expression
x == that
is equivalent toif (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
- 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 aClassCastException
at 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
ClassCastException
if the receiver object is not an instance of the erasure of typeT0
.
- 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.
- def ensuring(cond: (StringContext) => Boolean, msg: => Any): StringContext
- Implicit
- This member is added by an implicit conversion from StringContext toEnsuring[StringContext] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: (StringContext) => Boolean): StringContext
- Implicit
- This member is added by an implicit conversion from StringContext toEnsuring[StringContext] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: Boolean, msg: => Any): StringContext
- Implicit
- This member is added by an implicit conversion from StringContext toEnsuring[StringContext] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: Boolean): StringContext
- Implicit
- This member is added by an implicit conversion from StringContext toEnsuring[StringContext] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- 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 ofAnyRef
, and has three additional properties:- It is consistent: for any non-null instances
x
andy
of typeAnyRef
, multiple invocations ofx.eq(y)
consistently returnstrue
or consistently returnsfalse
. - For any non-null instance
x
of typeAnyRef
,x.eq(null)
andnull.eq(x)
returnsfalse
. null.eq(null)
returnstrue
.
When overriding the
equals
orhashCode
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
- It is consistent: for any non-null instances
- macro def f[A >: Any](args: A*): String
The formatted string interpolator.
The formatted string interpolator.
It inserts its arguments between corresponding parts of the string context. It also treats standard escape sequences as defined in the Scala specification. Finally, if an interpolated expression is followed by a
parts
string that starts with a formatting specifier, the expression is formatted according to that specifier. All specifiers allowed in Java format strings are handled, and in the same way they are treated in Java.For example:
val height = 1.9d val name = "James" println(f"$name%s is $height%2.2f meters tall") // James is 1.90 meters tall
- Exceptions thrown
IllegalArgumentException
if the number ofparts
in the enclosingStringContext
does not exceed the number of argumentsarg
by exactly 1.if a
parts
string contains a backslash (\
) character that does not start a valid escape sequence. Note: Thef
method works by assembling a format string from all theparts
strings and usingjava.lang.String.format
to format all arguments with that format string. The format string is obtained by concatenating allparts
strings, and performing two transformations:- Let a _formatting position_ be a start of any
parts
string except the first one. If a formatting position does not refer to a%
character (which is assumed to start a format specifier), then the string format specifier%s
is inserted. 2. Any%
characters not in formatting positions must begin one of the conversions%%
(the literal percent) or%n
(the platform-specific line separator).
- Let a _formatting position_ be a start of any
- 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 betweenfinalize
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
- 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 forString.format
(@see java.lang.String.format).- Implicit
- This member is added by an implicit conversion from StringContext toStringFormat[StringContext] performed by method StringFormat in scala.Predef.
- Definition Classes
- StringFormat
- Annotations
- @inline()
- final def getClass(): Class[_ <: AnyRef]
Returns the runtime class representation of the object.
- 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
true
if the receiver object is an instance of erasure of typeT0
;false
otherwise.
- Definition Classes
- Any
- 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
- 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
- val parts: String*
- 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
- macro def raw(args: Any*): String
The raw string interpolator.
The raw string interpolator.
It inserts its arguments between corresponding parts of the string context. As opposed to the simple string interpolator
s
, this one does not treat standard escape sequences as defined in the Scala specification.For example, the raw processed string
raw"a\nb"
is equal to the scala string"a\\nb"
.Note: Even when using the raw interpolator, Scala will process Unicode escapes. Unicode processing in the raw interpolator is deprecated as of scala 2.13.2 and will be removed in the future For example:
scala> raw"\u005cu0023" res0: String = #
- Exceptions thrown
IllegalArgumentException
if the number ofparts
in the enclosingStringContext
does not exceed the number of argumentsarg
by exactly 1.- Note
The Scala compiler may replace a call to this method with an equivalent, but more efficient, use of a StringBuilder.
- macro def s(args: Any*): String
The simple string interpolator.
The simple string interpolator.
It inserts its arguments between corresponding parts of the string context. It also treats standard escape sequences as defined in the Scala specification. Here's an example of usage:
val name = "James" println(s"Hello, $name") // Hello, James
In this example, the expression $name is replaced with the
toString
of the variablename
. Thes
interpolator can take thetoString
of any arbitrary expression within a${}
block, for example:println(s"1 + 1 = ${1 + 1}")
will print the string
1 + 1 = 2
.- Exceptions thrown
IllegalArgumentException
if the number ofparts
in the enclosingStringContext
does not exceed the number of argumentsarg
by exactly 1.StringContext.InvalidEscapeException
if aparts
string contains a backslash (\
) character that does not start a valid escape sequence.- Note
The Scala compiler may replace a call to this method with an equivalent, but more efficient, use of a StringBuilder.
- final def synchronized[T0](arg0: => T0): T0
Executes the code in
body
with an exclusive lock onthis
.Executes the code in
body
with an exclusive lock onthis
.- returns
the result of
body
- Definition Classes
- AnyRef
- final def wait(): Unit
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
- final def wait(arg0: Long, arg1: Int): Unit
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
- final def wait(arg0: Long): Unit
See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.
- object s
Deprecated Value Members
- def checkLengths(args: collection.Seq[Any]): Unit
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) use same-named method on StringContext companion object
- def standardInterpolator(process: (String) => String, args: Seq[Any]): String
- Annotations
- @deprecated
- Deprecated
(Since version 2.13.0) Use the static method StringContext.standardInterpolator instead of the instance method
- def →[B](y: B): (StringContext, B)
- Implicit
- This member is added by an implicit conversion from StringContext toArrowAssoc[StringContext] 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.
This is the documentation for the Scala standard library.
Package structure
The scala package contains core types like
Int
,Float
,Array
orOption
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 frameworkscala.collection.immutable
- Immutable, sequential data-structures such asVector
,List
,Range
,HashMap
orHashSet
scala.collection.mutable
- Mutable, sequential data-structures such asArrayBuffer
,StringBuilder
,HashMap
orHashSet
scala.collection.concurrent
- Mutable, concurrent data-structures such asTrieMap
scala.concurrent
- Primitives for concurrent programming such asFutures
andPromises
scala.io
- Input and output operationsscala.math
- Basic math functions and additional numeric types likeBigInt
andBigDecimal
scala.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.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 forscala.collection.immutable.List
.Other aliases refer to classes provided by the underlying platform. For example, on the JVM,
String
is an alias forjava.lang.String
.