Enum Collector.Characteristics

All Implemented Interfaces:
Serializable, Comparable<Collector.Characteristics>
Enclosing interface:
Collector<T,​A,​R>
public static enum Collector.Characteristics
extends Enum<Collector.Characteristics>

Characteristics indicating properties of a Collector, which can be used to optimize reduction implementations.

Enum Constants

Enum Constant Description
CONCURRENT

Indicates that this collector is concurrent, meaning that the result container can support the accumulator function being called concurrently with the same result container from multiple threads.
IDENTITY_FINISH

Indicates that the finisher function is the identity function and can be elided.
UNORDERED

Indicates that the collection operation does not commit to preserving the encounter order of input elements.

Methods

Modifier and Type Method Description
static Collector.Characteristics valueOf​(String name)

Returns the enum constant of this type with the specified name.
static Collector.Characteristics[] values()

Returns an array containing the constants of this enum type, in the order they are declared.

Methods declared in class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods declared in class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constants

CONCURRENT

public static final Collector.Characteristics CONCURRENT

Indicates that this collector is concurrent, meaning that the result container can support the accumulator function being called concurrently with the same result container from multiple threads.

If a CONCURRENT collector is not also UNORDERED, then it should only be evaluated concurrently if applied to an unordered data source.

UNORDERED

public static final Collector.Characteristics UNORDERED

Indicates that the collection operation does not commit to preserving the encounter order of input elements. (This might be true if the result container has no intrinsic order, such as a Set.)

IDENTITY_FINISH

public static final Collector.Characteristics IDENTITY_FINISH

Indicates that the finisher function is the identity function and can be elided. If set, it must be the case that an unchecked cast from A to R will succeed.

Methods

values

public static Collector.Characteristics[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows: 

for (Collector.Characteristics c : Collector.Characteristics.values())
    System.out.println(c);

Returns:
an array containing the constants of this enum type, in the order they are declared

valueOf

public static Collector.Characteristics valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:
name - the name of the enum constant to be returned.
Returns:
the enum constant with the specified name
Throws:
IllegalArgumentException - if this enum type has no constant with the specified name
NullPointerException - if the argument is null

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Documentation extracted from Debian's OpenJDK Development Kit package.
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https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/stream/Collector.Characteristics.html