public static enum Collector.Characteristics extends Enum<Collector.Characteristics>
Characteristics indicating properties of a Collector
, which can be used to optimize reduction implementations.
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.
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
.)
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.
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);
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.)
name
- the name of the enum constant to be returned.IllegalArgumentException
- if this enum type has no constant with the specified nameNullPointerException
- if the argument is null
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