CollectionConverters

object CollectionConverters extends AsJavaConverters with AsScalaConverters

This object contains methods that convert between Scala and Java collections.

The explicit conversion methods defined here are intended to be used in Java code. For Scala code, it is recommended to use the extension methods defined in scala.jdk.CollectionConverters.

Note: to create Java Streams that operate on Scala collections (sequentially or in parallel), use StreamConverters.

// Java Code
import scala.jdk.javaapi.CollectionConverters;
public class A {
  public void t(scala.collection.immutable.List<String> l) {
    java.util.List<String> jl = CollectionConverters.asJava(l);
  }
}

The conversions return adapters for the corresponding API, i.e., the collections are wrapped, not converted. Changes to the original collection are reflected in the view, and vice versa.

The following conversions are supported via asScala and asJava:

scala.collection.Iterable       <=> java.lang.Iterable
scala.collection.Iterator       <=> java.util.Iterator
scala.collection.mutable.Buffer <=> java.util.List
scala.collection.mutable.Set    <=> java.util.Set
scala.collection.mutable.Map    <=> java.util.Map
scala.collection.concurrent.Map <=> java.util.concurrent.ConcurrentMap

The following conversions are supported via asScala and through specially-named methods to convert to Java collections, as shown:

scala.collection.Iterable    <=> java.util.Collection   (via asJavaCollection)
scala.collection.Iterator    <=> java.util.Enumeration  (via asJavaEnumeration)
scala.collection.mutable.Map <=> java.util.Dictionary   (via asJavaDictionary)

In addition, the following one-way conversions are provided via asJava:

scala.collection.Seq         => java.util.List
scala.collection.mutable.Seq => java.util.List
scala.collection.Set         => java.util.Set
scala.collection.Map         => java.util.Map

The following one way conversion is provided via asScala:

java.util.Properties => scala.collection.mutable.Map

In all cases, converting from a source type to a target type and back again will return the original source object.

Source: CollectionConverters.scala

Linear Supertypes

AsScalaConverters, AsJavaConverters, AnyRef, Any

Ordering

Alphabetic
By Inheritance

Inherited

CollectionConverters
AsScalaConverters
AsJavaConverters
AnyRef
Any

Hide All
Show All

Visibility

Public
Protected

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 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
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
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.
def asJava[K, V](m: Map[K, V]): ConcurrentMap[K, V]
Converts a Scala mutable concurrent.Map to a Java ConcurrentMap.
Converts a Scala mutable concurrent.Map to a Java ConcurrentMap.
The returned Java ConcurrentMap is backed by the provided Scala concurrent.Map and any side-effects of using it via the Java interface will be visible via the Scala interface and vice versa.
If the Scala concurrent.Map was previously obtained from an implicit or explicit call of asScala then the original Java ConcurrentMap will be returned.
m
The Scala concurrent.Map to be converted.
returns
A Java ConcurrentMap view of the argument.
Definition Classes
AsJavaConverters
def asJava[K, V](m: Map[K, V]): Map[K, V]
Converts a Scala Map to a Java Map.
Converts a Scala Map to a Java Map.
The returned Java Map is backed by the provided Scala Map and any side-effects of using it via the Java interface will be visible via the Scala interface and vice versa.
If the Scala Map was previously obtained from an implicit or explicit call of asScala then the original Java Map will be returned.
m
The Scala Map to be converted.
returns
A Java Map view of the argument.
Definition Classes
AsJavaConverters
def asJava[K, V](m: Map[K, V]): Map[K, V]
Converts a Scala mutable Map to a Java Map.
Converts a Scala mutable Map to a Java Map.
The returned Java Map is backed by the provided Scala Map and any side-effects of using it via the Java interface will be visible via the Scala interface and vice versa.
If the Scala Map was previously obtained from an implicit or explicit call of asScala then the original Java Map will be returned.
m
The Scala mutable Map to be converted.
returns
A Java Map view of the argument.
Definition Classes
AsJavaConverters
def asJava[A](s: Set[A]): Set[A]
Converts a Scala Set to a Java Set.
Converts a Scala Set to a Java Set.
The returned Java Set is backed by the provided Scala Set and any side-effects of using it via the Java interface will be visible via the Scala interface and vice versa.
If the Scala Set was previously obtained from an implicit or explicit call of asScala then the original Java Set will be returned.
s
The Scala Set to be converted.
returns
A Java Set view of the argument.
Definition Classes
AsJavaConverters
def asJava[A](s: Set[A]): Set[A]
Converts a Scala mutable Set to a Java Set.
Converts a Scala mutable Set to a Java Set.
The returned Java Set is backed by the provided Scala Set and any side-effects of using it via the Java interface will be visible via the Scala interface and vice versa.
If the Scala Set was previously obtained from an implicit or explicit call of asScala then the original Java Set will be returned.
s
The Scala mutable Set to be converted.
returns
A Java Set view of the argument.
Definition Classes
AsJavaConverters
def asJava[A](s: collection.Seq[A]): java.util.List[A]
Converts a Scala Seq to a Java List.
Converts a Scala Seq to a Java List.
The returned Java List is backed by the provided Scala Seq and any side-effects of using it via the Java interface will be visible via the Scala interface and vice versa.
If the Scala Seq was previously obtained from an implicit or explicit call of asScala then the original Java List will be returned.
s
The Scala Seq to be converted.
returns
A Java List view of the argument.
Definition Classes
AsJavaConverters
def asJava[A](s: collection.mutable.Seq[A]): java.util.List[A]
Converts a Scala mutable Seq to a Java List.
Converts a Scala mutable Seq to a Java List.
The returned Java List is backed by the provided Scala Seq and any side-effects of using it via the Java interface will be visible via the Scala interface and vice versa.
If the Scala Seq was previously obtained from an implicit or explicit call of asScala then the original Java List will be returned.
s
The Scala Seq to be converted.
returns
A Java List view of the argument.
Definition Classes
AsJavaConverters
def asJava[A](b: Buffer[A]): java.util.List[A]
Converts a Scala mutable Buffer to a Java List.
Converts a Scala mutable Buffer to a Java List.
The returned Java List is backed by the provided Scala Buffer and any side-effects of using it via the Java interface will be visible via the Scala interface and vice versa.
If the Scala Buffer was previously obtained from an implicit or explicit call of asScala then the original Java List will be returned.
b
The Scala Buffer to be converted.
returns
A Java List view of the argument.
Definition Classes
AsJavaConverters
def asJava[A](i: collection.Iterable[A]): java.lang.Iterable[A]
Converts a Scala Iterable to a Java Iterable.
Converts a Scala Iterable to a Java Iterable.
The returned Java Iterable is backed by the provided Scala Iterable and any side-effects of using it via the Java interface will be visible via the Scala interface and vice versa.
If the Scala Iterable was previously obtained from an implicit or explicit call of asScala then the original Java Iterable will be returned.
i
The Scala Iterable to be converted.
returns
A Java Iterable view of the argument.
Definition Classes
AsJavaConverters
def asJava[A](i: collection.Iterator[A]): java.util.Iterator[A]
Converts a Scala Iterator to a Java Iterator.
Converts a Scala Iterator to a Java Iterator.
The returned Java Iterator is backed by the provided Scala Iterator and any side-effects of using it via the Java interface will be visible via the Scala interface and vice versa.
If the Scala Iterator was previously obtained from an implicit or explicit call of asScala then the original Java Iterator will be returned.
i
The Scala Iterator to be converted.
returns
A Java Iterator view of the argument.
Definition Classes
AsJavaConverters
def asJavaCollection[A](i: collection.Iterable[A]): Collection[A]
Converts a Scala Iterable to an immutable Java Collection.
Converts a Scala Iterable to an immutable Java Collection.
If the Scala Iterable was previously obtained from an implicit or explicit call of asScala then the original Java Collection will be returned.
i
The Scala Iterable to be converted.
returns
A Java Collection view of the argument.
Definition Classes
AsJavaConverters
def asJavaDictionary[K, V](m: Map[K, V]): Dictionary[K, V]
Converts a Scala mutable Map to a Java Dictionary.
Converts a Scala mutable Map to a Java Dictionary.
The returned Java Dictionary is backed by the provided Scala Dictionary and any side-effects of using it via the Java interface will be visible via the Scala interface and vice versa.
If the Scala Map was previously obtained from an implicit or explicit call of asScala then the original Java Dictionary will be returned.
m
The Scala Map to be converted.
returns
A Java Dictionary view of the argument.
Definition Classes
AsJavaConverters
def asJavaEnumeration[A](i: collection.Iterator[A]): java.util.Enumeration[A]
Converts a Scala Iterator to a Java Enumeration.
Converts a Scala Iterator to a Java Enumeration.
The returned Java Enumeration is backed by the provided Scala Iterator and any side-effects of using it via the Java interface will be visible via the Scala interface and vice versa.
If the Scala Iterator was previously obtained from an implicit or explicit call of asScala then the original Java Enumeration will be returned.
i
The Scala Iterator to be converted.
returns
A Java Enumeration view of the argument.
Definition Classes
AsJavaConverters
def asScala(p: Properties): Map[String, String]
Converts a Java Properties to a Scala mutable Map[String, String].
Converts a Java Properties to a Scala mutable Map[String, String].
The returned Scala Map[String, String] is backed by the provided Java Properties and any side-effects of using it via the Scala interface will be visible via the Java interface and vice versa.
p
The Java Properties to be converted.
returns
A Scala mutable Map[String, String] view of the argument.
Definition Classes
AsScalaConverters
def asScala[A, B](d: Dictionary[A, B]): Map[A, B]
Converts a Java Dictionary to a Scala mutable Map.
Converts a Java Dictionary to a Scala mutable Map.
The returned Scala Map is backed by the provided Java Dictionary and any side-effects of using it via the Scala interface will be visible via the Java interface and vice versa.
If the Java Dictionary was previously obtained from an implicit or explicit call of asJavaDictionary then the original Scala Map will be returned.
d
The Java Dictionary to be converted.
returns
A Scala mutable Map view of the argument.
Definition Classes
AsScalaConverters
def asScala[A, B](m: ConcurrentMap[A, B]): Map[A, B]
Converts a Java ConcurrentMap to a Scala mutable ConcurrentMap.
Converts a Java ConcurrentMap to a Scala mutable ConcurrentMap.
The returned Scala ConcurrentMap is backed by the provided Java ConcurrentMap and any side-effects of using it via the Scala interface will be visible via the Java interface and vice versa.
If the Java ConcurrentMap was previously obtained from an implicit or explicit call of asJava then the original Scala ConcurrentMap will be returned.
m
The Java ConcurrentMap to be converted.
returns
A Scala mutable ConcurrentMap view of the argument.
Definition Classes
AsScalaConverters
def asScala[A, B](m: Map[A, B]): Map[A, B]
Converts a Java Map to a Scala mutable Map.
Converts a Java Map to a Scala mutable Map.
The returned Scala Map is backed by the provided Java Map and any side-effects of using it via the Scala interface will be visible via the Java interface and vice versa.
If the Java Map was previously obtained from an implicit or explicit call of asJava then the original Scala Map will be returned.
If the wrapped map is synchronized (e.g. from java.util.Collections.synchronizedMap), it is your responsibility to wrap all non-atomic operations with underlying.synchronized. This includes get, as java.util.Map's API does not allow for an atomic get when null values may be present.
m
The Java Map to be converted.
returns
A Scala mutable Map view of the argument.
Definition Classes
AsScalaConverters
def asScala[A](s: Set[A]): Set[A]
Converts a Java Set to a Scala mutable Set.
Converts a Java Set to a Scala mutable Set.
The returned Scala Set is backed by the provided Java Set and any side-effects of using it via the Scala interface will be visible via the Java interface and vice versa.
If the Java Set was previously obtained from an implicit or explicit call of asJava then the original Scala Set will be returned.
s
The Java Set to be converted.
returns
A Scala mutable Set view of the argument.
Definition Classes
AsScalaConverters
def asScala[A](l: java.util.List[A]): Buffer[A]
Converts a Java List to a Scala mutable Buffer.
Converts a Java List to a Scala mutable Buffer.
The returned Scala Buffer is backed by the provided Java List and any side-effects of using it via the Scala interface will be visible via the Java interface and vice versa.
If the Java List was previously obtained from an implicit or explicit call of asJava then the original Scala Buffer will be returned.
l
The Java List to be converted.
returns
A Scala mutable Buffer view of the argument.
Definition Classes
AsScalaConverters
def asScala[A](c: Collection[A]): collection.Iterable[A]
Converts a Java Collection to a Scala Iterable.
Converts a Java Collection to a Scala Iterable.
If the Java Collection was previously obtained from an implicit or explicit call of asJavaCollection then the original Scala Iterable will be returned.
c
The Java Collection to be converted.
returns
A Scala Iterable view of the argument.
Definition Classes
AsScalaConverters
def asScala[A](i: java.lang.Iterable[A]): collection.Iterable[A]
Converts a Java Iterable to a Scala Iterable.
Converts a Java Iterable to a Scala Iterable.
The returned Scala Iterable is backed by the provided Java Iterable and any side-effects of using it via the Scala interface will be visible via the Java interface and vice versa.
If the Java Iterable was previously obtained from an implicit or explicit call of asJava then the original Scala Iterable will be returned.
i
The Java Iterable to be converted.
returns
A Scala Iterable view of the argument.
Definition Classes
AsScalaConverters
def asScala[A](e: java.util.Enumeration[A]): collection.Iterator[A]
Converts a Java Enumeration to a Scala Iterator.
Converts a Java Enumeration to a Scala Iterator.
The returned Scala Iterator is backed by the provided Java Enumeration and any side-effects of using it via the Scala interface will be visible via the Java interface and vice versa.
If the Java Enumeration was previously obtained from an implicit or explicit call of asJavaEnumeration then the original Scala Iterator will be returned.
e
The Java Enumeration to be converted.
returns
A Scala Iterator view of the argument.
Definition Classes
AsScalaConverters
def asScala[A](i: java.util.Iterator[A]): collection.Iterator[A]
Converts a Java Iterator to a Scala Iterator.
Converts a Java Iterator to a Scala Iterator.
The returned Scala Iterator is backed by the provided Java Iterator and any side-effects of using it via the Scala interface will be visible via the Java interface and vice versa.
If the Java Iterator was previously obtained from an implicit or explicit call of asJava then the original Scala Iterator will be returned.
i
The Java Iterator to be converted.
returns
A Scala Iterator view of the argument.
Definition Classes
AsScalaConverters
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
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
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
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
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()
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()
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.
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
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
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
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
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
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

Packages

Package structure

Automatic imports

CollectionConverters

object CollectionConverters extends AsJavaConverters with AsScalaConverters

Value Members

Inherited from AsScalaConverters

Inherited from AsJavaConverters

Inherited from AnyRef

Inherited from Any

Ungrouped

Packages

Package structure

Automatic imports

CollectionConverters

object CollectionConverters extends AsJavaConverters with AsScalaConverters

Value Members

Inherited from AsScalaConverters

Inherited from AsJavaConverters

Inherited from AnyRef

Inherited from Any

Ungrouped

CollectionConverters