abstract final class Boolean extends AnyVal
Boolean
(equivalent to Java's boolean
primitive type) is a
subtype of scala.AnyVal. Instances of Boolean
are not
represented by an object in the underlying runtime system.
There is an implicit conversion from scala.Boolean => scala.runtime.RichBoolean which provides useful non-primitive operations.
- Source
- Boolean.scala
- Alphabetic
- By Inheritance
- Boolean
- AnyVal
- Any
- by boolean2Boolean
- by booleanWrapper
- by any2stringadd
- by StringFormat
- by Ensuring
- by ArrowAssoc
- Hide All
- Show All
- Public
- Protected
Abstract Value Members
- abstract def !=(x: Boolean): Boolean
Compares two Boolean expressions and returns
true
if they evaluate to a different value.Compares two Boolean expressions and returns
true
if they evaluate to a different value.a != b
returnstrue
if and only ifa
istrue
andb
isfalse
ora
isfalse
andb
istrue
.
- abstract def &(x: Boolean): Boolean
Compares two Boolean expressions and returns
true
if both of them evaluate to true.Compares two Boolean expressions and returns
true
if both of them evaluate to true.a & b
returnstrue
if and only ifa
andb
aretrue
.
- Note
This method evaluates both
a
andb
, even if the result is already determined after evaluatinga
.
- abstract def &&(x: Boolean): Boolean
Compares two Boolean expressions and returns
true
if both of them evaluate to true.Compares two Boolean expressions and returns
true
if both of them evaluate to true.a && b
returnstrue
if and only ifa
andb
aretrue
.
- Note
This method uses 'short-circuit' evaluation and behaves as if it was declared as
def &&(x: => Boolean): Boolean
. Ifa
evaluates tofalse
,false
is returned without evaluatingb
.
- abstract def ==(x: Boolean): Boolean
Compares two Boolean expressions and returns
true
if they evaluate to the same value.Compares two Boolean expressions and returns
true
if they evaluate to the same value.a == b
returnstrue
if and only ifa
andb
aretrue
ora
andb
arefalse
.
- abstract def ^(x: Boolean): Boolean
Compares two Boolean expressions and returns
true
if they evaluate to a different value.Compares two Boolean expressions and returns
true
if they evaluate to a different value.a ^ b
returns
trueif and only if
a
istrue
andb
isfalse
ora
isfalse
andb
istrue
.
- abstract def unary_!: Boolean
Negates a Boolean expression.
Negates a Boolean expression.
-
!a
results infalse
if and only ifa
evaluates totrue
and -!a
results intrue
if and only ifa
evaluates tofalse
.- returns
the negated expression
- abstract def |(x: Boolean): Boolean
Compares two Boolean expressions and returns
true
if one or both of them evaluate to true.Compares two Boolean expressions and returns
true
if one or both of them evaluate to true.a | b
returnstrue
if and only ifa
istrue
orb
istrue
ora
andb
aretrue
.
- Note
This method evaluates both
a
andb
, even if the result is already determined after evaluatinga
.
- abstract def ||(x: Boolean): Boolean
Compares two Boolean expressions and returns
true
if one or both of them evaluate to true.Compares two Boolean expressions and returns
true
if one or both of them evaluate to true.a || b
returnstrue
if and only ifa
istrue
orb
istrue
ora
andb
aretrue
.
- Note
This method uses 'short-circuit' evaluation and behaves as if it was declared as
def ||(x: => Boolean): Boolean
. Ifa
evaluates totrue
,true
is returned without evaluatingb
.
Concrete 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
- 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
- Any
- def +(other: String): String
- Implicit
- This member is added by an implicit conversion from Boolean toany2stringadd[Boolean] performed by method any2stringadd in scala.Predef.
- Definition Classes
- any2stringadd
- def ->[B](y: B): (Boolean, B)
- Implicit
- This member is added by an implicit conversion from Boolean toArrowAssoc[Boolean] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
- Annotations
- @inline()
- def <(that: Boolean): Boolean
Returns true if
this
is less thanthat
- def <=(that: Boolean): Boolean
Returns true if
this
is less than or equal tothat
. - final def ==(arg0: Any): Boolean
Test two objects for equality.
Test two objects for equality. 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
- Any
- def >(that: Boolean): Boolean
Returns true if
this
is greater thanthat
. - def >=(that: Boolean): Boolean
Returns true if
this
is greater than or equal tothat
. - 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 ofT0
, 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
whenT0
is a primitive type. WhenT0
is primitive,asInstanceOf
may insert a conversion instead of a type test. If your intent is to convert, use atoT
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 ofT0
, if that can be checked on this platform
- when flow analysis fails to deduce
- def booleanValue(): Boolean
- Implicit
- This member is added by an implicit conversion from Boolean tojava.lang.Boolean performed by method boolean2Boolean in scala.Predef.
- Definition Classes
- Boolean
- def compare(y: Boolean): Int
Result of comparing
this
with operandthat
.Result of comparing
this
with operandthat
.Implement this method to determine how instances of A will be sorted.
Returns
x
where:x < 0
whenthis < that
x == 0
whenthis == that
x > 0
whenthis > that
- def compareTo(arg0: java.lang.Boolean): Int
- Implicit
- This member is added by an implicit conversion from Boolean tojava.lang.Boolean performed by method boolean2Boolean in scala.Predef.
- Definition Classes
- Boolean → Comparable
- def compareTo(that: Boolean): Int
Result of comparing
this
with operandthat
. - def ensuring(cond: (Boolean) => Boolean, msg: => Any): Boolean
- Implicit
- This member is added by an implicit conversion from Boolean toEnsuring[Boolean] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: (Boolean) => Boolean): Boolean
- Implicit
- This member is added by an implicit conversion from Boolean toEnsuring[Boolean] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: Boolean, msg: => Any): Boolean
- Implicit
- This member is added by an implicit conversion from Boolean toEnsuring[Boolean] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def ensuring(cond: Boolean): Boolean
- Implicit
- This member is added by an implicit conversion from Boolean toEnsuring[Boolean] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
- def equals(arg0: Any): Boolean
Compares the receiver object (
this
) with the argument object (that
) for equivalence.Compares the receiver object (
this
) with the argument object (that
) for equivalence.Any implementation of this method should be an equivalence relation:
- It is reflexive: for any instance
x
of typeAny
,x.equals(x)
should returntrue
. - It is symmetric: for any instances
x
andy
of typeAny
,x.equals(y)
should returntrue
if and only ify.equals(x)
returnstrue
. - It is transitive: for any instances
x
,y
, andz
of typeAny
ifx.equals(y)
returnstrue
andy.equals(z)
returnstrue
, thenx.equals(z)
should returntrue
.
If you override this method, you should verify that your implementation remains an equivalence relation. Additionally, when overriding this method it is usually necessary to override
hashCode
to ensure that objects which are "equal" (o1.equals(o2)
returnstrue
) hash to the same scala.Int. (o1.hashCode.equals(o2.hashCode)
).- returns
true
if the receiver object is equivalent to the argument;false
otherwise.
- Definition Classes
- Any
- It is reflexive: for any instance
- def getClass(): Class[Boolean]
Returns the runtime class representation of the object.
- def hashCode(): Int
Calculate a hash code value for the object.
Calculate a hash code value for the object.
The default hashing algorithm is platform dependent.
Note that it is allowed for two objects to have identical hash codes (
o1.hashCode.equals(o2.hashCode)
) yet not be equal (o1.equals(o2)
returnsfalse
). A degenerate implementation could always return0
. However, it is required that if two objects are equal (o1.equals(o2)
returnstrue
) that they have identical hash codes (o1.hashCode.equals(o2.hashCode)
). Therefore, when overriding this method, be sure to verify that the behavior is consistent with theequals
method.- returns
the hash code value for this object.
- Definition Classes
- Any
- 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 returnstrue
if the value of the receiver object is aBigDecimal
or a subtype ofBigDecimal
.T0
is a parameterized class type, e.g.List[Int]
: this method returnstrue
if the value of the receiver object is someList[X]
for anyX
. For example,List(1, 2, 3).isInstanceOf[List[String]]
will return true.T0
is some singleton typex.type
or literalx
: this method returnsthis.eq(x)
. For example,x.isInstanceOf[1]
is equivalent tox.eq(1)
T0
is an intersectionX with Y
orX & Y: this method is equivalent to
x.isInstanceOf[X] && x.isInstanceOf[Y]T0
is a unionX | Y
: this method is equivalent tox.isInstanceOf[X] || x.isInstanceOf[Y]
T0
is a type parameter or an abstract type member: this method is equivalent toisInstanceOf[U]
whereU
isT0
's upper bound,Any
ifT0
is unbounded. For example,x.isInstanceOf[A]
whereA
is an unbounded type parameter will return true for any value ofx
.
This is exactly equivalent to the type pattern
_: T0
- returns
true
if the receiver object is an instance of erasure of typeT0
;false
otherwise.
- Definition Classes
- Any
- Note
due to the unexpectedness of
List(1, 2, 3).isInstanceOf[List[String]]
returning true andx.isInstanceOf[A]
whereA
is a type parameter or abstract member returning true, these forms issue a warning.
- val self: Boolean
- def toString(): 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
- 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.
- Implicit
- This member is added by an implicit conversion from Boolean tojava.lang.Boolean performed by method boolean2Boolean in scala.Predef.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(boolean: java.lang.Boolean).equals(arg0)
- Definition Classes
- Boolean → AnyRef → Any
- 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.
- Implicit
- This member is added by an implicit conversion from Boolean tojava.lang.Boolean performed by method boolean2Boolean in scala.Predef.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(boolean: java.lang.Boolean).hashCode()
- Definition Classes
- Boolean → AnyRef → Any
- 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.
- Implicit
- This member is added by an implicit conversion from Boolean tojava.lang.Boolean performed by method boolean2Boolean in scala.Predef.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(boolean: java.lang.Boolean).toString()
- Definition Classes
- Boolean → AnyRef → Any
- def toString(): 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.
- Implicit
- This member is added by an implicit conversion from Boolean toRichBoolean performed by method booleanWrapper in scala.LowPriorityImplicits.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(boolean: RichBoolean).toString()
- Definition Classes
- Proxy → Any
Deprecated Value Members
- 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 Boolean toStringFormat[Boolean] performed by method StringFormat in scala.Predef.
- Definition Classes
- StringFormat
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.12.16) Use
formatString.format(value)
instead ofvalue.formatted(formatString)
, or use thef""
string interpolator. In Java 15 and later,formatted
resolves to the new method in String which has reversed parameters.
- def →[B](y: B): (Boolean, B)
- Implicit
- This member is added by an implicit conversion from Boolean toArrowAssoc[Boolean] 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
.